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Arabei S.M.,Belarusian State Agrarian Technical University | Galaup J.-P.,University Paris - Sud | McCaffrey J.G.,National University of Ireland, Maynooth | Shafizadeh N.,CNRS Orsay Institute for Molecular Science | Crepin C.,CNRS Orsay Institute for Molecular Science
Low Temperature Physics | Year: 2012

This paper deals with our on-going work on the electronic spectroscopy of tetrapyrrole molecules embedded in cryogenic hosts. Under nanosecond laser excitation of free-base tetrabenzoporphin molecules in a nitrogen matrix at 8 K, increasing laser pulse energy results in essential enhancement of the intensity of one or several vibronic emission lines in the fine-structure fluorescence spectrum. Some characteristics of stimulated radiation are realized in the observed intense monochromatic radiation as a result of a transition from the purely electronic S1 level to a vibrational sublevel of the S0 state, corresponding to the excitation of C-C stretching vibrations of tetrapyrrole methane bridges. We also report on persistent spectral hole-burning effects. Hole and antihole formation analysis gives some insight on the photochemical properties of tetrabenzoporphin in a nitrogen matrix. © 2012 American Institute of Physics. Source


Arabei S.,Belarusian State Agrarian Technical University | McCaffrey J.G.,National University of Ireland | Galaup J.-P.,University Paris - Sud | Shafizadeh N.,CNRS Orsay Institute for Molecular Science | Crepin C.,CNRS Orsay Institute for Molecular Science
Physical Chemistry Chemical Physics | Year: 2015

Thin cryogenic samples of inert gas solids doped with free-base tetraazaporphine (H2TAP) were irradiated with a tunable pulsed laser. Under resonant electronic excitation of the guest, specific vibronic transitions of the fluorescence spectra were found to be strongly enhanced with only a moderate increase of the laser power. This enhancement is due to stimulated emission (SE). The characteristics of SE bands are described in the three hosts (Ar, N2, and Ne) explored, as well as their excitation spectra. SE is observed in transitions involving different vibrational modes of the guest, depending on the host and the electronic excitation. The results are discussed in comparison with previous works on other tetrapyrrolic molecules trapped in inert gas matrices. From this comparison the key features required to observe SE are deduced to be: (1) SE can be obtained with various tetrapyrrolic molecules; (2) free-base molecules are preferable to their metallo-counterparts; (3) the results highlight a specific molecular vibrational mode involved in the process; and (4) cryogenic crystal structures are also of importance in the detection of SE. © the Owner Societies 2015. Source


Crepin C.,CNRS Orsay Institute for Molecular Science | Shafizadeh N.,CNRS Orsay Institute for Molecular Science | Chin W.,CNRS Orsay Institute for Molecular Science | Galaup J.-P.,University Paris - Sud | And 2 more authors.
Low Temperature Physics | Year: 2010

An unexpected phenomenon was revealed in the laser induced fluorescence spectra of free-base (H2Pc) and zinc (ZnPc) phthalocyanines trapped in rare gas and nitrogen matrices under a moderate increase in the laser intensity. In all matrices the intensity of an emission band near 755nm increased drastically when pumping the S1←S0 transition. This observation was assigned to stimulated emission in a four-level scheme involving a vibronic transition from the lowest electronic state to a vibrational level of the ground state. In the present work, we expose new similar results obtained with porphyrin molecules, i.e. tetra-benzoporphin (TBP). With free-base H2TBP, stimulated emission was observed in Ar or N2 matrices, but not in Xe matrices. A possible reason could be a fast inter-system crossing rate due to the heavy atom effect induced by Xe. We also report the observation of persistent burnt spectral holes, although the low efficiency of this process is not competitive with stimulated emission and no decrease of the stimulated emission with time was observed. With ZnTBP no stimulated emission could be recorded but the appearance of rather strong phosphorescence was noticed. Similar studies focusing on the stimulated emission phenomenon is that they should allow new insights into site effects and site selectivity. © 2010 American Institute of Physics. Source


Arabei S.M.,Belarusian State Agrarian Technical University | Pavich T.A.,B. I. Stepanov Institute of Physics | Solovyov K.N.,B. I. Stepanov Institute of Physics
Journal of Porphyrins and Phthalocyanines | Year: 2013

In this mini-review, we present the main results of our works on the spectroscopy of the molecules of tetrapyrrole pigments incorporated into nanoporous gel matrices. Xerogels activated by organic dyes are promising materials for applications in various fields of technology. The influence of the technique of embedment of the activator molecules on their physico-chemical properties has been analyzed. The specificity of the action of a silicate matrix as external medium, as compared to liquid and solid solutions, is shown. © 2013 World Scientific Publishing Company. Source


Babkov L.M.,Chernyshevsky Saratov State University | Ivlieva I.V.,Chernyshevsky Saratov State University | Korolevich M.V.,Belarusian State Agrarian Technical University
Journal of Applied Spectroscopy | Year: 2015

The structures of isolated 2,3-di-O-nitromethyl-β-D-glucopyranoside and its H-bonded complexes were modeled using density functional method B3LYP/6-31G(d). Their IR spectra were calculated in the harmonic approximation. It was concluded based on the modeling results that the H-bond affected the structure and IR spectrum of 2,3-di-Onitromethyl-β-D-glucopyranoside. The IR spectrum measured in the range 600–3700 cm–1 at room temperature was interpreted. © 2015 Springer Science+Business Media New York Source

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