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Doktorov A.B.,RAS Institute of Chemical Kinetics and Combustion
Zeitschrift fur Physikalische Chemie | Year: 2017

The relations have been analytically derived for recombination yields of radical pairs with different precursor states and by different reaction channels (singlet and/or triplet) in arbitrary magnetic and microwave fields. Recombination of two particles from a radical pair mostly with anisotropic reactivity is assumed to take place in a narrow reaction zone, and relative translation motion including rotation of reactants may be an arbitrary stochastic process. In addition, the approach may take into account the time-dependent spin Hamiltonian. The novel method for the calculation of recombination yields is suggested, and general expressions for recombination yields are derived for strong singlet-triplet dephasing. Some of the relations and expressions are the basis of the results given in the literature and their generalization to the case of non-model reacting systems that does not use simplification of reactants structure and reactants motion in solutions. © 2017 Walter de Gruyter GmbH.


Strekalov M.L.,RAS Institute of Chemical Kinetics and Combustion
Journal of Experimental and Theoretical Physics | Year: 2017

A wave packet formed by a linear superposition of bound states with an arbitrary energy spectrum returns arbitrarily close to the initial state after a quite long time. A method in which quantum recovery times are calculated exactly is developed. In particular, an exact analytic expression is derived for the recovery time in the limiting case of a two-level system. In the general case, the reciprocal recovery time is proportional to the Gauss distribution that depends on two parameters (mean value and variance of the return probability). The dependence of the recovery time on the mean excitation level of the system is established. The recovery time is the longest for the maximal excitation level. © 2017, Pleiades Publishing, Inc.


Strekalov M.L.,RAS Institute of Chemical Kinetics and Combustion
Journal of Mathematical Chemistry | Year: 2015

The coupled vibration–dissociation–recombination process has been examined for diatomic molecules and atoms. The relationship between the concentrations of reagent molecules, product atoms and the instantaneous dissociation rate is established in an analytical form. A very accurate approach similar to the technique of uniform approximation is used to solve a relevant nonlinear differential equation. An exact analytical solution to the master equation is obtained for the model of strong collisions. © 2015, Springer International Publishing Switzerland.


Strekalov M.L.,RAS Institute of Chemical Kinetics and Combustion
Chemical Physics | Year: 2011

Collisional energy transfer between highly excited molecules and bath gas is considered as a stochastic process occurring in energy space. It is assumed that the density of vibrational states of polyatomic molecules is energy-dependent. An exact solution to the master equation for conditional probability density is given in terms of simple analytical formulas for weak and strong collisions. The bulk-average moments of internal energy and the average moments of energy transfer are calculated analytically. The place occupied by the collisional transfer of vibrational energy among other stochastic processes is discussed. © 2011 Elsevier B.V. All rights reserved.


Strekalov M.L.,RAS Institute of Chemical Kinetics and Combustion
Chemical Physics | Year: 2010

An exact relationship between the transition probability P(E → E ′) and quantum transition probabilities Pi →f of an active molecule under the effect of collisions with medium molecules is obtained. Treating an active molecule as a system of harmonic oscillators, it is possible to derive the analytical expression for P(E → E′) from the "first principles" using the first-order perturbation theory for probabilities Pi→f. The only parameter of the model is expressed in terms of vibrational relaxation time that may be calculated numerically or taken from experiments. For the system of harmonic oscillators placed in a thermal bath, the solution of the master equation is found in the analytical form. An extended discussion of the model is also presented. © 2010 Elsevier B.V. All rights reserved.


Strekalov M.L.,RAS Institute of Chemical Kinetics and Combustion
Chemical Physics Letters | Year: 2010

The influence of the energy-dependent density of states on the collisional relaxation of highly vibrationally excited molecules is analyzed in non-reactive systems. An integral equation is solved to construct transition probability, which satisfies detailed balance and is normalized to unity at all initial energies from zero to infinity. Transition probabilities are obtained for a multiexponential model with an energy-dependent density of states. © 2010 Elsevier B.V. All rights reserved.


Strekalov M.L.,RAS Institute of Chemical Kinetics and Combustion
Chemical Physics Letters | Year: 2012

Collisional energy transfer between highly rotationally excited molecules and bath gas is considered as a stochastic process occurring in energy space. An exact solution to master equation for the population density is given in terms of simple analytical formulas for weak and strong collisions. The strong collisions are shown to manifest themselves in the distribution pattern composed of maxima and minima in the energy dependence of population density. This effect is explained in detail on physical grounds. The bulk averages of rotational energy moments and energy transfer moments are calculated analytically. © 2012 Elsevier B.V. All rights reserved.


Zarko V.E.,RAS Institute of Chemical Kinetics and Combustion
Combustion, Explosion and Shock Waves | Year: 2010

Polynitrogen compounds (containing only nitrogen atoms) are promising candidates as energetic materials for rocket engineering. The high energy content of these compounds is due to the significant difference in bond energy between nitrogen atoms. In particular, molecular nitrogen (N 2) is characterized by a uniquely strong triple bond - 229 kcal/mole, whereas the single-bond energy is only 38.4 kcal/mole. From theoretical estimates, use of polynitrogen compounds can provide a specific impulse of 350-500 sec with material density in a range of 2.0-3.9 g/cm 3. This paper gives a brief review of the current status of experimental and theoretical studies in the chemistry of polynitrogen compounds. © 2010 Springer Science + Business Media, Inc.


Fedorenko S.G.,RAS Institute of Chemical Kinetics and Combustion
Chemical Physics | Year: 2010

After photo-induced ionization a free electron suffers a quick conversion to a solvated state, and then can recombine with the parent atom or ion. However, high mobility and reactivity of a free electron can allow the electron to delocalize and recombine in the free state. The theory of two channel processes of geminate electron recombination is developed here for the general type of the Markovian motion of reactants. A contact model is used for analytical solution of the problem of geminate recombination of neutral and charged reactants. The theory is applied to the experiment of three-pulse generation of excess electrons in water. © 2010 Elsevier B.V. All rights reserved.


Bazhin N.,RAS Institute of Chemical Kinetics and Combustion
Energy and Environmental Science | Year: 2010

The theory of the transport of dissolved methane, nitrogen and other atmospheric gases in the sedimentary (active) layers of wetlands and rice fields and its fluxes to the atmosphere has been developed. The transport equation describing the diffusion of dissolved molecules among the gas bubbles was derived. The problem of the influence of vegetation on the concentrations of dissolved methane and its fluxes has been considered. A good agreement is shown to exist between theory and experiment. © 2010 The Royal Society of Chemistry.

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