Laboratory of Laser Photochemistry

Head of the Laboratory: Prof. A.K. Petrov, Dr. Sci.
Researchers:E.N. Chesnokov, Dr. Sci.
V.P. Maltsev, Dr. Sci.
A.A. Onischuk , Dr.Sci
G.A. Kovalskaya, Cand. Sci.
A.S.Kozlov, Cand. Sci.
A.I. Chichinin, Cand. Sci.
L.V. Kuibida, Cand.Sci.
A.V. Chernyshev, Cand. Sci.
S.R. Gorelik, Cand. Sci.
M.A. Ushakova

Kinetics and mechanism of chemical reactions involving excited atoms, radicals and molecules.

Investigations are performed in the field of laser photochemistry, a novel direction of Physical Chemistry in which the scientists of the ICK&C have made a substantial contribution. The main directions and results of the investigations are the following:

- A method has been developed to study the kinetics of homogeneous (not involving the reactor walls) thermal gas-phase reactions under IR radiation of a continuous CO₂ laser.

- IR-multiphoton dissociation of molecules under the action of a pulsed CO₂ laser is investigated; a cascade method of laser separation of isotopes has been proposed.

- Pioneering investigations of the reactivity of vibrationally excited molecules and radicals have been performed .

- The decomposition of excited molecules under the action of overtone absorption of UV and visible laser radiation is studied.

- An original time-resolved technique of intracavity absorption of laser radiation has been developed; a series of investigations into the kinetics of radical reactions in the gas phase has been carried out.

- The mechanism of exothermic radical reactions is studied using IR chemiluminescence method.

- A set-up for time-resolved laser magnetic resonance has been created and used as a basis for the series of investigations into the kinetics of radical reactions.

- The mechanism of thermal decomposition of silane and the effect of heterogeneous stages at the surface of the formed aerosol particles are under investigation.

- An original scanning flow cytometer set-up has been developed and built. The indicatrix of laser light scattering on single particles is used to determine their size (0.5 – 20 microns), shape and refractive index which allowed wide use of this set-up to analyse biological objects (erythrocytes, lymphocytes, cells, bacteria, etc.), as well as to study polymerisation mechanisms.

Great expectations of the researchers are connected with the construction, together with the Institute of Nuclear Physics, of the Centre of Photochemical Investigations on the basis of the free electron laser (FEL). The members of the laboratory have already obtained pioneering results in using FEL radiation in physicochemical investigations (in the Duke University, USA). In particular, multiphoton dissociation of various molecules has been performed and the separation of carbon, oxygen and nitrogen isotopes has been carried out [14, 15].

1. Yu. N. Molin, V.N. Panfilov, A.K. Petrov, Infrared Photochemistry. Nauka Publishers, Novosibirsk, 1985, 255 p. (in Russian).

2. A.B. Vakhtin and A.K. Petrov, "Absolute rate constants of R + NO (+M) ® RNO (+ M) reactions (R = C₃F₇, CF₃, CH₃) at T = 295 K measured by time-resolved intracavity absorption of He-Ne laser radiation", Chem. Phys., 1991, 149, 427 - 436.

3. S.R. Gorelik, E.N. Chesnokov, "Formation of vibrationally excited CO₂ molecules by reaction of O (¹D) with formaldehyde", Chem. Phys. Reports, 1997, 16, 195-210.

4. A.V. Baklanov, A.I. Chichinin, "Time-resolved LMR measurement of the rate constants of the reactions SiH₃+SiH₃ and SiH₃+Cl", Chem. Phys., 1994, 181, 119-128.

5. A. A. Onischuk, V. P. Strunin, M.A. Ushakova, and V. N. Panfilov "Studying of Silane Thermal Decomposition Mechanism", Int. J. Chem. Kinet. 1998, 30, 99-110.

6. J.T. Soini, A.V. Chernyshev, P.E. Hanninen, E. Soini, V.P. Maltsev, "A new design of the flow cuvette and optical set up for the scanning flow citometer", Cytometry, 1998, 31, 78-84.

7. A.K.Petrov, E.N.Chesnokov, S.R. Gorelik, K.D.Straub, J.M.J. Madey, E.B. Szarmes. Multiphoton isotope - selective dissociation of formic acid molecules under action of a free electron laser, J.Phys.Chem. A, 1997, 101, 7200-7207.