Institute of Physical Chemistry

Bucharest, Romania

Institute of Physical Chemistry

Bucharest, Romania
SEARCH FILTERS
Time filter
Source Type

News Article | May 4, 2017
Site: www.rdmag.com

Light initiates many chemical reactions. Experiments at the Laser Centre of the Institute of Physical Chemistry of the Polish Academy of Sciences and the University of Warsaw's Faculty of Physics have for the first time demonstrated that increasing the intensity of illumination some reactions can be significantly faster. Here, acceleration was achieved using pairs of ultrashort laser pulses. Light-induced reactions can be accelerated by increasing the intensity of illumination -- this has been demonstrated in experiments carried out at the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw. In order to thoroughly investigate the nature of the processes involved, ultra-short consecutive pairs of laser pulses were used, and an increase in the rate of reaction between the molecules was observed by up to several dozen percent. The observations of the Warsaw scientists have been reported in the well-known scientific journal Physical Chemistry Chemical Physics. "Our experiments provide fundamental knowledge about the physical processes that are important for the course of important light-induced reactions. This knowledge can potentially be used in many applications, especially when dealing with high intensity light sources. These include, among others, various microscopic imaging techniques, ultra-fast spectroscopy as well as photovoltaics, particularly if light-focusing devices such as solar collectors are used," says Dr. Gonzalo Angulo (IPC PAS). In light-induced reactions, a photon with the appropriate energy excites a molecule of dye. When there is a molecule of quencher near the excited molecule, an interaction takes place: there may be a transfer of energy, an electron or a proton, between the two reactants. Reactions of this type are common in nature. A good example is electron transfer in photosynthesis, which plays a key role in the formation of the Earth's ecosystem. It turns out that a factor that can influence the acceleration of reactions is the intensity of the light that initiates them. In order to study the nature of the processes taking place, the Warsaw chemists used laser pulses lasting femtoseconds instead of the traditional continuous stream of light. The energy of the impulses was adjusted so that, under their influence, the dye molecules moved into the excited energy state. The pulses were grouped in pairs. The interval between pulses in a pair was several dozen picoseconds (trillionths of a second) and was matched to the type of reacting molecules and the environment of the solution. "The theory and the experiments required care and attention, but the physical idea itself is quite simple here," notes Jadwiga Milkiewicz, a PhD student at IPC PAS, and explains: "In order for the reaction to occur, there must be a molecule of quencher near the light-excited dye molecule. So, if we have a pair of molecules that have already reacted with each other this means that they were close enough to each other. By increasing the number of photons in time, we thus increase the chance that if, after the reaction, both molecules have managed to return to their ground state, the absorption of a new photon by the dye has the potential to initiate another reaction before the molecules move away from each other in space." The course of reactions in solutions depends on many factors such as temperature, pressure, viscosity or the presence of an electric or magnetic field. The research at the IPC PAS has proved that these factors also influence the acceleration of the chemical reaction that occurs with an increased intensity of illumination. Under some conditions, the acceleration of the reaction was unnoticeable, in optimal conditions the rate of the reaction increased by up to 25-30%. "In our experiments so far, we have concentrated on light-induced electron transfer reactions, that is, those which change the electrical charge of the molecules. However, we do not see any reason why the mechanism we have observed could not function in other variations of these reactions. So, in the near future, we will try to confirm its efficacy in energy transfer reactions or in reactions involving also proton transfer," says Dr. Angulo.


News Article | May 4, 2017
Site: www.eurekalert.org

Light initiates many chemical reactions. Experiments at the Laser Centre of the Institute of Physical Chemistry of the Polish Academy of Sciences and the University of Warsaw's Faculty of Physics have for the first time demonstrated that increasing the intensity of illumination some reactions can be significantly faster. Here, acceleration was achieved using pairs of ultrashort laser pulses. Light-induced reactions can be accelerated by increasing the intensity of illumination -- this has been demonstrated in experiments carried out at the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw. In order to thoroughly investigate the nature of the processes involved, ultra-short consecutive pairs of laser pulses were used, and an increase in the rate of reaction between the molecules was observed by up to several dozen percent. The observations of the Warsaw scientists have been reported in the well-known scientific journal Physical Chemistry Chemical Physics. "Our experiments provide fundamental knowledge about the physical processes that are important for the course of important light-induced reactions. This knowledge can potentially be used in many applications, especially when dealing with high intensity light sources. These include, among others, various microscopic imaging techniques, ultra-fast spectroscopy as well as photovoltaics, particularly if light-focusing devices such as solar collectors are used," says Dr. Gonzalo Angulo (IPC PAS). In light-induced reactions, a photon with the appropriate energy excites a molecule of dye. When there is a molecule of quencher near the excited molecule, an interaction takes place: there may be a transfer of energy, an electron or a proton, between the two reactants. Reactions of this type are common in nature. A good example is electron transfer in photosynthesis, which plays a key role in the formation of the Earth's ecosystem. It turns out that a factor that can influence the acceleration of reactions is the intensity of the light that initiates them. In order to study the nature of the processes taking place, the Warsaw chemists used laser pulses lasting femtoseconds instead of the traditional continuous stream of light. The energy of the impulses was adjusted so that, under their influence, the dye molecules moved into the excited energy state. The pulses were grouped in pairs. The interval between pulses in a pair was several dozen picoseconds (trillionths of a second) and was matched to the type of reacting molecules and the environment of the solution. "The theory and the experiments required care and attention, but the physical idea itself is quite simple here," notes Jadwiga Milkiewicz, a PhD student at IPC PAS, and explains: "In order for the reaction to occur, there must be a molecule of quencher near the light-excited dye molecule. So, if we have a pair of molecules that have already reacted with each other this means that they were close enough to each other. By increasing the number of photons in time, we thus increase the chance that if, after the reaction, both molecules have managed to return to their ground state, the absorption of a new photon by the dye has the potential to initiate another reaction before the molecules move away from each other in space." The course of reactions in solutions depends on many factors such as temperature, pressure, viscosity or the presence of an electric or magnetic field. The research at the IPC PAS has proved that these factors also influence the acceleration of the chemical reaction that occurs with an increased intensity of illumination. Under some conditions, the acceleration of the reaction was unnoticeable, in optimal conditions the rate of the reaction increased by up to 25-30%. "In our experiments so far, we have concentrated on light-induced electron transfer reactions, that is, those which change the electrical charge of the molecules. However, we do not see any reason why the mechanism we have observed could not function in other variations of these reactions. So, in the near future, we will try to confirm its efficacy in energy transfer reactions or in reactions involving also proton transfer," says Dr. Angulo. In addition to physicists and chemists from the IPC PAS and the Physics Faculty of the University of Warsaw, financed by the HARMONIA grant of the National Science Centre, a group headed by Prof. Gunther Grampp from Graz University of Technology participated in the experiments. In the Austrian laboratory, comparative experiments were carried out on samples illuminated in a continuous manner. Also involved in the team's theoretical work was Dr. Daniel Kattnig from the University of Oxford. This press release was prepared with funds from the European ERA Chairs grant under the Horizon 2020 programme. The Institute of Physical Chemistry of the Polish Academy of Sciences was established in 1955 as one of the first chemical institutes of the PAS. The Institute's scientific profile is strongly related to the newest global trends in the development of physical chemistry and chemical physics. Scientific research is conducted in nine scientific departments. CHEMIPAN R&D Laboratories, operating as part of the Institute, implement, produce and commercialise specialist chemicals to be used, in particular, in agriculture and pharmaceutical industry. The Institute publishes approximately 200 original research papers annually.


News Article | May 4, 2017
Site: www.rdmag.com

In classical computer science information is stored in bits, in quantum computer science -- in quantum bits, i.e. qubits. Experiments at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw prove that not only physics, but also chemistry is suitable for storing information. The role of the chemical bit, the 'chit', can be fulfilled by a simple arrangement of three droplets in contact with each other, in which oscillatory reactions occur. The computer, smartphone, digital camera -- none of these devices could work without memory chips. In typical electronic memory, zero and one are recorded, stored and read by physical phenomena such as the flow of electricity or the change in electrical or magnetic properties of the medium. Dr. Konrad Gizynski and Prof. Jerzy Gorecki from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw have demonstrated a working memory of a different kind, based on chemical phenomena. A single bit is stored here in three adjoining droplets, between which chemical reaction fronts propagate steadily, cyclically, and in a strictly defined manner. The chemical foundations of the memory constructed by the IPC PAS researchers is the Belousov-Zhabotinsky (BZ) reaction. The course of the reaction is oscillatory: when one cycle is over, the reagents necessary to start the next cycle are reconstituted in the solution. Before the reaction stops, there are usually several tens to hundreds of oscillations. They are accompanied by a regular change in the colour of the solution, caused by ferroin -- the reaction catalyst. The second catalyst used by the Warsaw researchers was ruthenium. The introduction of ruthenium was of key significance because it causes the BZ reaction to become photosensitive: when the solution is illuminated by blue light it ceases to oscillate. This feature makes it possible to control the course of the reaction. "Our idea for the chemical storage of information was simple. From our previous experiments we knew that when Belousov-Zhabotinsky droplets are in contact, chemical fronts can propagate from droplet to droplet. So we decided to look for the smallest droplet systems in which excitations could take place in several ways, with at least two being stable. We could then assign one sequence of excitations a logic value of 0, the other 1, and in order to switch between them, that is, to force a particular change of memory state, we could use light," explains Prof. Gorecki. Experiments were carried out in a container filled with a thin layer of lipid solution in oil (decane). Small amounts of oscillating solution added to the system with a pipette formed droplets. These were positioned above the ends of optical fibres brought to the base of the container. To prevent the droplets from sliding off the optical fibres, each was immobilized by several rods protruding from the base of the container. The search began with a study of pairs of coupled droplets. Four types (modes) of oscillation can take place in these: droplet 1 excites droplet 2, droplet 2 excites droplet 1, both droplets excite each other simultaneously, both excite each other alternately (i.e., when one is excited, the other one is in the refractory phase). "In paired droplet systems, most often one droplet excited the other. Unfortunately, only one mode of this type was always stable, and we needed two," says Dr. Gizynski and explains: "Both droplets are made up of the same solution, but they never have exactly the same dimensions. As a result, in each droplet the chemical oscillations occur at a slightly different pace. In such cases, the droplet oscillating more slowly begins to adjust its rhythm to its faster 'friend'. Even if it were possible with light to force the slower oscillating droplet to excite the faster oscillating droplet, the system would in any case return to the mode in which the faster droplet stimulated the slower one." In this situation, the IPC PAS researchers looked into triplets of adjoining droplets arranged in a triangle (so each droplet touched its two neighbours). Chemical fronts can propagate here in many ways: droplets may oscillate simultaneously, in anti-phase, two droplets can oscillate simultaneously and force oscillations in the third, etc. The researchers were most interested in rotational modes, in which the chemical fronts passed from droplet to droplet in a 1-2-3 sequence or in the opposite direction (3-2-1). A droplet in which the Belousov-Zhabotinsky reaction proceeds excites rapidly, but it takes much longer for it to return to its initial state and only when it has reached this it can become excited again. So if in the 1-2-3 mode the excitation were to reach droplet 3 too quickly, it would not get through to droplet 1 to initiate a new cycle, because droplet 1 would not have enough time to 'rest'. As a result, the rotational mode would disappear. IPC PAS researchers were only interested in rotational modes capable of multiple repetitions of the cycle of excitations. They had an added advantage: the chemical fronts circulating between the droplets resemble a spiral wave, and waves of this type are characterized by increased stability. Experiments showed that both of the studied rotational modes are stable and if a system enters one of them, it remains in it until the Belousov-Zhabotinsky reaction ceases. It was also proved that by correctly selecting the time and length of illumination of appropriate droplets, the direction of rotation of the excitations can be changed. The triplet droplet system, with multiple chemical fronts, was thus capable of permanently storing one of two logic states. "In fact, our chemical bit has a slightly greater potential than the classical bit. The rotational modes we used to record states 0 and 1 had the shortest oscillation periods of 18.7 and 19.5 seconds, respectively. So if the system oscillated any slower, we could talk about an additional third logic state," commented Dr. Gizynski and notes that this third state could be used not to store information but, for example, to verify the correctness of the record. The research on memory made up of oscillating droplets, financed by the National Science Centre, was basic in nature and served only to demonstrate that stable storage of information using chemical reactions is possible. In the newly formed memory reactions were only responsible for storing information, while its recording and reading required physical methods. It is still probably many years before a fully chemical memory can be built that could become part of a future chemical computer.


News Article | May 4, 2017
Site: www.rdmag.com

In classical computer science information is stored in bits, in quantum computer science -- in quantum bits, i.e. qubits. Experiments at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw prove that not only physics, but also chemistry is suitable for storing information. The role of the chemical bit, the 'chit', can be fulfilled by a simple arrangement of three droplets in contact with each other, in which oscillatory reactions occur. The computer, smartphone, digital camera -- none of these devices could work without memory chips. In typical electronic memory, zero and one are recorded, stored and read by physical phenomena such as the flow of electricity or the change in electrical or magnetic properties of the medium. Dr. Konrad Gizynski and Prof. Jerzy Gorecki from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw have demonstrated a working memory of a different kind, based on chemical phenomena. A single bit is stored here in three adjoining droplets, between which chemical reaction fronts propagate steadily, cyclically, and in a strictly defined manner. The chemical foundations of the memory constructed by the IPC PAS researchers is the Belousov-Zhabotinsky (BZ) reaction. The course of the reaction is oscillatory: when one cycle is over, the reagents necessary to start the next cycle are reconstituted in the solution. Before the reaction stops, there are usually several tens to hundreds of oscillations. They are accompanied by a regular change in the colour of the solution, caused by ferroin -- the reaction catalyst. The second catalyst used by the Warsaw researchers was ruthenium. The introduction of ruthenium was of key significance because it causes the BZ reaction to become photosensitive: when the solution is illuminated by blue light it ceases to oscillate. This feature makes it possible to control the course of the reaction. "Our idea for the chemical storage of information was simple. From our previous experiments we knew that when Belousov-Zhabotinsky droplets are in contact, chemical fronts can propagate from droplet to droplet. So we decided to look for the smallest droplet systems in which excitations could take place in several ways, with at least two being stable. We could then assign one sequence of excitations a logic value of 0, the other 1, and in order to switch between them, that is, to force a particular change of memory state, we could use light," explains Prof. Gorecki. Experiments were carried out in a container filled with a thin layer of lipid solution in oil (decane). Small amounts of oscillating solution added to the system with a pipette formed droplets. These were positioned above the ends of optical fibres brought to the base of the container. To prevent the droplets from sliding off the optical fibres, each was immobilized by several rods protruding from the base of the container. The search began with a study of pairs of coupled droplets. Four types (modes) of oscillation can take place in these: droplet 1 excites droplet 2, droplet 2 excites droplet 1, both droplets excite each other simultaneously, both excite each other alternately (i.e., when one is excited, the other one is in the refractory phase). "In paired droplet systems, most often one droplet excited the other. Unfortunately, only one mode of this type was always stable, and we needed two," says Dr. Gizynski and explains: "Both droplets are made up of the same solution, but they never have exactly the same dimensions. As a result, in each droplet the chemical oscillations occur at a slightly different pace. In such cases, the droplet oscillating more slowly begins to adjust its rhythm to its faster 'friend'. Even if it were possible with light to force the slower oscillating droplet to excite the faster oscillating droplet, the system would in any case return to the mode in which the faster droplet stimulated the slower one." In this situation, the IPC PAS researchers looked into triplets of adjoining droplets arranged in a triangle (so each droplet touched its two neighbours). Chemical fronts can propagate here in many ways: droplets may oscillate simultaneously, in anti-phase, two droplets can oscillate simultaneously and force oscillations in the third, etc. The researchers were most interested in rotational modes, in which the chemical fronts passed from droplet to droplet in a 1-2-3 sequence or in the opposite direction (3-2-1). A droplet in which the Belousov-Zhabotinsky reaction proceeds excites rapidly, but it takes much longer for it to return to its initial state and only when it has reached this it can become excited again. So if in the 1-2-3 mode the excitation were to reach droplet 3 too quickly, it would not get through to droplet 1 to initiate a new cycle, because droplet 1 would not have enough time to 'rest'. As a result, the rotational mode would disappear. IPC PAS researchers were only interested in rotational modes capable of multiple repetitions of the cycle of excitations. They had an added advantage: the chemical fronts circulating between the droplets resemble a spiral wave, and waves of this type are characterized by increased stability. Experiments showed that both of the studied rotational modes are stable and if a system enters one of them, it remains in it until the Belousov-Zhabotinsky reaction ceases. It was also proved that by correctly selecting the time and length of illumination of appropriate droplets, the direction of rotation of the excitations can be changed. The triplet droplet system, with multiple chemical fronts, was thus capable of permanently storing one of two logic states. "In fact, our chemical bit has a slightly greater potential than the classical bit. The rotational modes we used to record states 0 and 1 had the shortest oscillation periods of 18.7 and 19.5 seconds, respectively. So if the system oscillated any slower, we could talk about an additional third logic state," commented Dr. Gizynski and notes that this third state could be used not to store information but, for example, to verify the correctness of the record. The research on memory made up of oscillating droplets, financed by the National Science Centre, was basic in nature and served only to demonstrate that stable storage of information using chemical reactions is possible. In the newly formed memory reactions were only responsible for storing information, while its recording and reading required physical methods. It is still probably many years before a fully chemical memory can be built that could become part of a future chemical computer.


News Article | May 4, 2017
Site: www.eurekalert.org

In classical computer science information is stored in bits, in quantum computer science -- in quantum bits, i.e. qubits. Experiments at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw prove that not only physics, but also chemistry is suitable for storing information. The role of the chemical bit, the 'chit', can be fulfilled by a simple arrangement of three droplets in contact with each other, in which oscillatory reactions occur. The computer, smartphone, digital camera -- none of these devices could work without memory chips. In typical electronic memory, zero and one are recorded, stored and read by physical phenomena such as the flow of electricity or the change in electrical or magnetic properties of the medium. Dr. Konrad Gizynski and Prof. Jerzy Gorecki from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw have demonstrated a working memory of a different kind, based on chemical phenomena. A single bit is stored here in three adjoining droplets, between which chemical reaction fronts propagate steadily, cyclically, and in a strictly defined manner. The chemical foundations of the memory constructed by the IPC PAS researchers is the Belousov-Zhabotinsky (BZ) reaction. The course of the reaction is oscillatory: when one cycle is over, the reagents necessary to start the next cycle are reconstituted in the solution. Before the reaction stops, there are usually several tens to hundreds of oscillations. They are accompanied by a regular change in the colour of the solution, caused by ferroin -- the reaction catalyst. The second catalyst used by the Warsaw researchers was ruthenium. The introduction of ruthenium was of key significance because it causes the BZ reaction to become photosensitive: when the solution is illuminated by blue light it ceases to oscillate. This feature makes it possible to control the course of the reaction. "Our idea for the chemical storage of information was simple. From our previous experiments we knew that when Belousov-Zhabotinsky droplets are in contact, chemical fronts can propagate from droplet to droplet. So we decided to look for the smallest droplet systems in which excitations could take place in several ways, with at least two being stable. We could then assign one sequence of excitations a logic value of 0, the other 1, and in order to switch between them, that is, to force a particular change of memory state, we could use light," explains Prof. Gorecki. Experiments were carried out in a container filled with a thin layer of lipid solution in oil (decane). Small amounts of oscillating solution added to the system with a pipette formed droplets. These were positioned above the ends of optical fibres brought to the base of the container. To prevent the droplets from sliding off the optical fibres, each was immobilized by several rods protruding from the base of the container. The search began with a study of pairs of coupled droplets. Four types (modes) of oscillation can take place in these: droplet 1 excites droplet 2, droplet 2 excites droplet 1, both droplets excite each other simultaneously, both excite each other alternately (i.e., when one is excited, the other one is in the refractory phase). "In paired droplet systems, most often one droplet excited the other. Unfortunately, only one mode of this type was always stable, and we needed two," says Dr. Gizynski and explains: "Both droplets are made up of the same solution, but they never have exactly the same dimensions. As a result, in each droplet the chemical oscillations occur at a slightly different pace. In such cases, the droplet oscillating more slowly begins to adjust its rhythm to its faster 'friend'. Even if it were possible with light to force the slower oscillating droplet to excite the faster oscillating droplet, the system would in any case return to the mode in which the faster droplet stimulated the slower one." In this situation, the IPC PAS researchers looked into triplets of adjoining droplets arranged in a triangle (so each droplet touched its two neighbours). Chemical fronts can propagate here in many ways: droplets may oscillate simultaneously, in anti-phase, two droplets can oscillate simultaneously and force oscillations in the third, etc. The researchers were most interested in rotational modes, in which the chemical fronts passed from droplet to droplet in a 1-2-3 sequence or in the opposite direction (3-2-1). A droplet in which the Belousov-Zhabotinsky reaction proceeds excites rapidly, but it takes much longer for it to return to its initial state and only when it has reached this it can become excited again. So if in the 1-2-3 mode the excitation were to reach droplet 3 too quickly, it would not get through to droplet 1 to initiate a new cycle, because droplet 1 would not have enough time to 'rest'. As a result, the rotational mode would disappear. IPC PAS researchers were only interested in rotational modes capable of multiple repetitions of the cycle of excitations. They had an added advantage: the chemical fronts circulating between the droplets resemble a spiral wave, and waves of this type are characterized by increased stability. Experiments showed that both of the studied rotational modes are stable and if a system enters one of them, it remains in it until the Belousov-Zhabotinsky reaction ceases. It was also proved that by correctly selecting the time and length of illumination of appropriate droplets, the direction of rotation of the excitations can be changed. The triplet droplet system, with multiple chemical fronts, was thus capable of permanently storing one of two logic states. "In fact, our chemical bit has a slightly greater potential than the classical bit. The rotational modes we used to record states 0 and 1 had the shortest oscillation periods of 18.7 and 19.5 seconds, respectively. So if the system oscillated any slower, we could talk about an additional third logic state," commented Dr. Gizynski and notes that this third state could be used not to store information but, for example, to verify the correctness of the record. The research on memory made up of oscillating droplets, financed by the National Science Centre, was basic in nature and served only to demonstrate that stable storage of information using chemical reactions is possible. In the newly formed memory reactions were only responsible for storing information, while its recording and reading required physical methods. It is still probably many years before a fully chemical memory can be built that could become part of a future chemical computer. This press release was prepared with funds from the European ERA Chairs grant under the Horizon 2020 programme. The Institute of Physical Chemistry of the Polish Academy of Sciences was established in 1955 as one of the first chemical institutes of the PAS. The Institute's scientific profile is strongly related to the newest global trends in the development of physical chemistry and chemical physics. Scientific research is conducted in nine scientific departments. CHEMIPAN R&D Laboratories, operating as part of the Institute, implement, produce and commercialise specialist chemicals to be used, in particular, in agriculture and pharmaceutical industry. The Institute publishes approximately 200 original research papers annually.


News Article | May 7, 2017
Site: news.yahoo.com

Researchers from the Institute of Physical Chemistry at the Polish Academy of Sciences in Warsaw have demonstrated it is possible to use chemical reactions to store information. The findings of their experiments, described in a study published in the latest edition of the journal Physical Chemistry Chemical Physics, could one day be used to construct a fully-functioning "chemical computer." The researchers were able to create a chemical bit using three adjoining droplets, between which chemical reaction fronts propagated steadily and cyclically. Their experiments, which used a thin layer of lipid solution in oil — to which small quantities of solution had been added — showed that a Belousov-Zhabotinsky (BZ) reaction, a kind of oscillating chemical reaction, can be used as a chemical foundation of memory. "Our idea for the chemical storage of information was simple. From our previous experiments, we knew that when Belousov-Zhabotinsky droplets are in contact, chemical fronts can propagate from droplet to droplet. So we decided to look for the smallest droplet systems in which excitations could take place in several ways, with at least two being stable. We could then assign one sequence of excitations a logic value of 0, the other 1, and in order to switch between them and force a particular change of memory state, we could use light," study co-author Jerzy Gorecki said in a statement. For the purpose of their study, the researchers took three adjoining droplets arranged in a triangle. This allowed them to overcome a hurdle that systems with pairs of coupled droplets could not surmount. "In paired droplet systems, most often, one droplet excited the other. Unfortunately, only one mode of this type was always stable, and we needed two," co-author Konrad Gizynski explained in the statement. "Both droplets are made up of the same solution, but they never have exactly the same dimensions. As a result, in each droplet, the chemical oscillations occur at a slightly different pace. In such cases, the droplet oscillating more slowly begins to adjust its rhythm to its faster 'friend.' Even if it were possible with light to force the slower oscillating droplet to excite the faster oscillating droplet, the system would return to the mode in which the faster droplet stimulated the slower one." The experiments revealed that both rotational modes in the system — the one in which the chemical fronts passed from droplet to droplet in a 1-2-3 sequence, and the other in which it did so in the opposite direction (3-2-1) — were stable, and if the system enters one of them, it remains so until the Belousov-Zhabotinsky reaction is complete. Of course, this does not mean scientists are any closer to building a viable and efficient chemical computer, as the system is still not capable of recording and reading the stored information. However, the experiments do prove that chemical bits are stable enough to store information. "In fact, our chemical bit has a slightly greater potential than the classical bit. The rotational modes we used to record states zero and one had the shortest oscillation periods of 18.7 and 19.5 seconds, respectively. So if the system oscillated any slower, we could talk about an additional third logic state," Gizynski said.


News Article | May 4, 2017
Site: www.rdmag.com

Light initiates many chemical reactions. Experiments at the Laser Centre of the Institute of Physical Chemistry of the Polish Academy of Sciences and the University of Warsaw's Faculty of Physics have for the first time demonstrated that increasing the intensity of illumination some reactions can be significantly faster. Here, acceleration was achieved using pairs of ultrashort laser pulses. Light-induced reactions can be accelerated by increasing the intensity of illumination -- this has been demonstrated in experiments carried out at the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw. In order to thoroughly investigate the nature of the processes involved, ultra-short consecutive pairs of laser pulses were used, and an increase in the rate of reaction between the molecules was observed by up to several dozen percent. The observations of the Warsaw scientists have been reported in the well-known scientific journal Physical Chemistry Chemical Physics. "Our experiments provide fundamental knowledge about the physical processes that are important for the course of important light-induced reactions. This knowledge can potentially be used in many applications, especially when dealing with high intensity light sources. These include, among others, various microscopic imaging techniques, ultra-fast spectroscopy as well as photovoltaics, particularly if light-focusing devices such as solar collectors are used," says Dr. Gonzalo Angulo (IPC PAS). In light-induced reactions, a photon with the appropriate energy excites a molecule of dye. When there is a molecule of quencher near the excited molecule, an interaction takes place: there may be a transfer of energy, an electron or a proton, between the two reactants. Reactions of this type are common in nature. A good example is electron transfer in photosynthesis, which plays a key role in the formation of the Earth's ecosystem. It turns out that a factor that can influence the acceleration of reactions is the intensity of the light that initiates them. In order to study the nature of the processes taking place, the Warsaw chemists used laser pulses lasting femtoseconds instead of the traditional continuous stream of light. The energy of the impulses was adjusted so that, under their influence, the dye molecules moved into the excited energy state. The pulses were grouped in pairs. The interval between pulses in a pair was several dozen picoseconds (trillionths of a second) and was matched to the type of reacting molecules and the environment of the solution. "The theory and the experiments required care and attention, but the physical idea itself is quite simple here," notes Jadwiga Milkiewicz, a PhD student at IPC PAS, and explains: "In order for the reaction to occur, there must be a molecule of quencher near the light-excited dye molecule. So, if we have a pair of molecules that have already reacted with each other this means that they were close enough to each other. By increasing the number of photons in time, we thus increase the chance that if, after the reaction, both molecules have managed to return to their ground state, the absorption of a new photon by the dye has the potential to initiate another reaction before the molecules move away from each other in space." The course of reactions in solutions depends on many factors such as temperature, pressure, viscosity or the presence of an electric or magnetic field. The research at the IPC PAS has proved that these factors also influence the acceleration of the chemical reaction that occurs with an increased intensity of illumination. Under some conditions, the acceleration of the reaction was unnoticeable, in optimal conditions the rate of the reaction increased by up to 25-30%. "In our experiments so far, we have concentrated on light-induced electron transfer reactions, that is, those which change the electrical charge of the molecules. However, we do not see any reason why the mechanism we have observed could not function in other variations of these reactions. So, in the near future, we will try to confirm its efficacy in energy transfer reactions or in reactions involving also proton transfer," says Dr. Angulo.


News Article | May 5, 2017
Site: phys.org

In typical electronic memory, zeros and ones are recorded, stored and read by physical phenomena such as the flow of electricity or the change in electrical or magnetic properties. Dr. Konrad Gizynski and Prof. Jerzy Gorecki from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw have demonstrated a working memory based on chemical phenomena. A single bit is stored here in three adjoining droplets, between which chemical reaction fronts propagate steadily, cyclically, and in a strictly defined manner. The chemical foundation of this form of memory is the Belousov-Zhabotinsky (BZ) reaction. The course of the reaction is oscillatory. When one cycle ends, the reagents necessary to start the next cycle are reconstituted in the solution. Before the reaction stops, there are usually several tens to hundreds of oscillations. They are accompanied by a regular change in the colour of the solution, caused by ferroin—the reaction catalyst. The second catalyst used by the Warsaw researchers was ruthenium. The introduction of ruthenium causes the BZ reaction to become photosensitive—when the solution is illuminated by blue light, it ceases to oscillate. This feature makes it possible to control the course of the reaction. "Our idea for the chemical storage of information was simple. From our previous experiments, we knew that when Belousov-Zhabotinsky droplets are in contact, chemical fronts can propagate from droplet to droplet. So we decided to look for the smallest droplet systems in which excitations could take place in several ways, with at least two being stable. We could then assign one sequence of excitations a logic value of 0, the other 1, and in order to switch between them and force a particular change of memory state, we could use light," explains Prof. Gorecki. Experiments were carried out in a container filled with a thin layer of lipid solution in oil (decane). Small amounts of oscillating solution added to the system with a pipette formed droplets. These were positioned above the ends of optical fibres brought to the base of the container. To prevent the droplets from sliding off the optical fibres, each was immobilized by several rods protruding from the base of the container. The search began with a study of pairs of coupled droplets in which four types (modes) of oscillation can take place: droplet one excites droplet two; droplet two excites droplet one; both droplets excite each other simultaneously; both excite each other alternately (i.e., when one is excited, the other one is in the refractory phase). "In paired droplet systems, most often, one droplet excited the other. Unfortunately, only one mode of this type was always stable, and we needed two," says Dr. Gizynski. "Both droplets are made up of the same solution, but they never have exactly the same dimensions. As a result, in each droplet, the chemical oscillations occur at a slightly different pace. In such cases, the droplet oscillating more slowly begins to adjust its rhythm to its faster 'friend.' Even if it were possible with light to force the slower oscillating droplet to excite the faster oscillating droplet, the system would return to the mode in which the faster droplet stimulated the slower one." In this situation, the IPC PAS researchers looked into triplets of adjoining droplets arranged in a triangle (so each droplet touched its two neighbours). Chemical fronts can propagate here in many ways: Droplets may oscillate simultaneously in anti-phase, two droplets can oscillate simultaneously and force oscillations in the third, etc. The researchers were most interested in rotational modes, in which the chemical fronts passed from droplet to droplet in a 1-2-3 sequence or in the opposite direction (3-2-1). A droplet in which the Belousov-Zhabotinsky reaction proceeds excites rapidly, but it takes much longer for it to return to its initial state and only then can become excited again. So if in the 1-2-3 mode the excitation were to reach droplet three too quickly, it would not get through to droplet one to initiate a new cycle, because droplet one would not have enough time to 'rest.' As a result, the rotational mode would disappear. IPC PAS researchers were only interested in rotational modes capable of multiple repetitions of the cycle of excitations. They had an added advantage: The chemical fronts circulating between the droplets resemble a spiral wave, and waves of this type are characterized by increased stability. Experiments showed that both of the studied rotational modes are stable, and if a system enters one of them, it remains until the Belousov-Zhabotinsky reaction ceases. It was also proved that by correctly selecting the time and length of illumination of appropriate droplets, the direction of rotation of the excitations can be changed. The triplet droplet system, with multiple chemical fronts, was thus capable of permanently storing one of two logic states. "In fact, our chemical bit has a slightly greater potential than the classical bit. The rotational modes we used to record states zero and one had the shortest oscillation periods of 18.7 and 19.5 seconds, respectively. So if the system oscillated any slower, we could talk about an additional third logic state," commented Dr. Gizynski, and notes that this third state could be used, for example, to verify the correctness of the record. The research on memory made up of oscillating droplets was basic in nature and served only to demonstrate that stable storage of information using chemical reactions is possible. The newly formed memory reactions were only responsible for storing information, while its recording and reading required physical methods. It will likely be many years before a fully functioning chemical memory can be built as part of a future chemical computer. Explore further: The prototype of a chemical computer detects a sphere More information: Konrad Gizynski et al, Chemical memory with states coded in light controlled oscillations of interacting Belousov–Zhabotinsky droplets, Phys. Chem. Chem. Phys. (2017). DOI: 10.1039/c6cp07492h


News Article | May 26, 2017
Site: www.materialstoday.com

Conventional computers use bits of information, binary digits. The quantum computer will use qubits, quantum bits. Now, researchers at the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw, have demonstrated that the chemical bit, the chit, can be formed from three touching droplets undergoing strictly defined oscillatory chemical reactions. Konrad Gizynski and Jerzy Gorecki have demonstrated working memory in such a system based on the well-known Belousov-Zhabotinsky (BZ) oscillating reaction. In their system, the team added ruthenium as well as the standard ferroin catalyst in the BZ reaction. This additional catalyst makes the system photosensitive so that shining a blue light on it halts the oscillation. "Our idea for the chemical storage of information was simple," explains Gorecki. "From our previous experiments we knew that when BZ droplets are in contact, chemical fronts can propagate from droplet to droplet. So we decided to look for the smallest droplet systems in which excitations could take place in several ways, with at least two being stable. We could then assign one sequence of excitations a logic value of 0, the other 1, and in order to switch between them, that is, to force a particular change of memory state, we could use light." The team's proof of principle involved pipetting the requisite three droplets into decane and positioning the system above the ends of optical fibers. The droplets form a triangle so that each droplet touches its two neighbors and oscillatory chemical fronts can propagate through this arrangement in different ways. They were after a reversible "1-2-3" sequence that would give them two states to represent a "1" and a "0" in binary. Moreover, a circular sequence like this would resemble a spiral wave and so be more stable than back and forth oscillations. The team then showed that correctly selecting the time and length of illumination of appropriate droplets, they could change the direction of rotation 1-2-3 to 3-2-1, giving them control over the binary state. [Gizynski and Gorecki, Phys Chem Chem Phys (2017): DOI: 10.1039/c6cp07492h] "In fact, our chemical bit has a slightly greater potential than the classical bit. The rotational modes we used to record states 0 and 1 had the shortest oscillation periods of 18.7 and 19.5 seconds, respectively. So if the system oscillated any slower, we could talk about an additional third logic state," adds Gizynski. The third state in this case could be used as a check digit. The research itself is of a fundamental nature at this stage, of course, we are probably some time away before a true chemical computer using chits becomes a reality. "We have [also] published a numerical paper on BZ-droplets based classifiers where light is used to implement a classification function into a system composed of 25 interacting BZ droplets," Gizynski told Materials Today. "Now, we're working on building such a classifier in experimental system." Figure: Three droplets with circulating chemical fronts can store information. The first chemical bit has been demonstrated by researchers from the Institute of Physical Chemistry of the Polish Academy of Sciences in Warsaw. (Image credit: IPC PAS, Grzegorz Krzyzewski) David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".


Munch A.S.,Institute of Physical Chemistry | Mertens F.O.R.L.,Institute of Physical Chemistry
Journal of Materials Chemistry | Year: 2012

The development of cyclic preparation techniques based on the application of an SBU (secondary building unit) precursor and a linker solution for the generation of MOF (metal-organic framework) coatings were used to prepare HKUST-1 (Hong Kong University of Science and Technology-1) coated capillary gas-chromatographic columns. As a prerequisite for the conducted preparation of the coatings some optimisation of the procedure for the generation of the MOF material at room temperature was carried out. Beside the demonstration of their general suitability for the separation of permanent gases, the capillaries were used to perform isothermal retention time measurements with analytes possessing electron donating capabilities, such as aromatic or oxygen containing compounds. Since HKUST-1 possesses SBUs with open metal sites, the heat of adsorption and the adsorption entropy were determined to address the question whether or not coordinative contributions may affect the analyte-MOF interaction. © 2012 The Royal Society of Chemistry.

Loading Institute of Physical Chemistry collaborators
Loading Institute of Physical Chemistry collaborators