NEW MODIFICATIONS OF MATRIX-ISOLATION ELECTRON-SPIN-RESONANCE SPECTROSCOPY

Two new modifications of matrix-isolation electron spin resonance spec troscopy (MIESR) are developed, one of them is designed to study eleme ntary reactions, while the other is used for complex gas-phase and het erophase reactions. The first modification combines both high sensitiv ity of matrix isolation and high time resolution due to a rapid gas fl ow. Radicals were trapped from the high-rate gas flow using diffusion to the freezing zone under the pressure of 1 - 2 torr. The rate consta nt of the reaction HO2. + NO --> OH. + NO2 as well as the probabilitie s of trapping the radicals HO2., FO2., CH3O2. were measured with the h elp of this technique. The second modification is the combination of E SR/LMR, applied to the gas phase, with matrix isolation of radicals. S ensitivity of the latter is as high as that of both ESR and LMR, appli ed separately. The combination allows one to markedly enhance the oppo rtunities provided by each of the methods. It is particularly the case for the resolution of the spectra of HO2. and RO(2)(.) in the solid p hase by means of simultaneous detection of HO2. in the gas phase by LM R and HO2. + RO(2)(.) being isolated in the matrix.