The Laboratory of Chemistry and Physics of Free Radicals
Head of Laboratory:S.A.Dzuba, Prof., Dr. Sci.
Researchers:
Yu.D. Tsvetkov, Academician
A.D. Milov, Cand. Sci.
R.I. Samoilova, Cand. Sci.
Maryasov A.G., Cand. Sci.
Kulik L.V., Cand.Sci.

 
 
 
 

Research Area

Structure and properties of free radicals, kinetics and mechanisms of chemical reactions involving free radicals, development of radiospectroscopic methods for these purposes.
 

Research Activities

Studies of dipole-dipole interactions of free radicals by means of pulsed EPR spectroscopy. Experimental and theoretical principles of electron spin echo (ESE) have been developed. This method is used to study the spatial distribution of radicals by measuring weak dipole-dipole interactions in various irradiated substances. Non-homogeneous structure of radical tracks in frozen polar matrices was investigated and their geometric parameters have been determined. Pulsed double resonance method has been recently developed and used to obtain information about space structure of spin labelled peptides.

Investigation of modulation phenomena in ESE of polyoriented systems. These studies created the principles of a new direction in radiospectroscopy, namely, ESEEM-spectroscopy which provides high resolution and efficiency in the studies of weak magnetic electron-nuclear interactions. This kind of spectroscopy helped to obtain the data on the structure of traps for electrons, atoms and radicals in irradiated matrices, on the structure of solvate coats for a series of organic radicals and atoms, on the features of their interactions with solid adsorbents. The method has found wide application in the investigations of paramagnetic complexes of biological importance. In the works carried out jointly with the scientists from the Netherlands and Japan, ESEEM spectroscopy helped to obtain the information concerning the structure of paramagnetic particles in photosynthesis reaction centres and their interactions with the neighbouring peptides.

Investigations of the mobility and reactions of active particles in the condensed phase. A novel complex of methods has been developed involving pulsed ESR tomography, ESE-detected ESR spectroscopy, laser photoelectrochemistry in wide wavelength range. These methods are extensively used to study superslow motions (with characteristic time up to 10-2 s) of organic radicals, as well as small-amplitude libration motions, the mechanism of electron polarisation transfer in liquid. These methods have also been used to measure rate constants of various elementary photochemical reactions, spatial distribution of intermediates in these reactions. Thermalisation lengths and mechanism of slow electrons (0.2 – 3.8 eV) in polar media has been investigated; lifetimes of a series of anion radicals have been determined.

The development of the experimental basis and its maintenance are provided by the engineering technical group. Pulsed and continuous wave EPR spectrometers operating in the millimetre microwave band are being developed and adjusted.
 

International cooperation:

University of Leiden, The Netherlands (Professor A. J. Hoff, Dr. J. Raap).

Pacific North-West National Laboratory, USA, Richland (Dr. M.K. Bowman).

Heustone University, Department of Chemistry, USA (Prof. L. Kevan).

Kwansei Gakuin University, Nishinomia, Japan (Prof. A. Kawamory).

Tohoku University, Sendai, Japan (Prof. S. Yamauchi).

Agricultural University, Wageningen, The Netherlands (Dr. Hoekstra).
 

Selected publications:

1. K.M. Salikhov, A.G.Semenov, Yu. D. Tsvetkov, Electron spin echo and its applications, Nauka Publishers, Novosibirsk, 1976.

2. K.M.Salikhov, Yu.D.Tsvetkov. “Electron spin echo studies of spin-spin interactions in solids”, in “Time domain electron spin resonance”. ed. by L. Keyan. J. Wiley and Sons inc. 1979, p.231.

3. S.A.Dzuba, Yu. D. Tsvetkov, Molecular dynamics in disordered media, Nauka Publishers, Novosibirsk, 1991.

4. S.A.Dikanov, Yu.D.Tsvetkov. Electron spin echo envelope modulation (ESEEM) spectroscopy, CRC Press, 1992.

5. S.A.Dzuba, Yu.D.Tsvetkov. “Pulsed ESR and molecular motions”, Appl. Magn. Reson., 1, 179 (1991).

6. A.D.Milov, A.G.Maryasov, Yu.D.Tsvetkov. “Pulsed electron double resonance (PELDOR) and its applications in free radicals research”. Appl. Magnetic Reson. 15, 107 (1998).

Address
Dzuba Sergei A.

Institute of Chemical Kinetics and Combustion, Siberian Branch of RAS
Institutskaya str., 3
630090 Novosibirsk, Russia
Phone: (383) 3331276
Fax: (383) 3342350
E-mail: dzuba@ns.kinetics.nsc.ru