Low Temperature Physics: 29, 519 (2003); https://doi.org/10.1063/1.1582334 (3 pages)
EPR spectra and rotation of CH3, CH2D, CHD2, and CD3 radicals in solid H2
Yu.A. Dmitriev and R.A. Zhitnikov
A.F. Ioffe Physico-Technical Institute, 26 Politekhnicheskaya Str, St. Petersburg 194021, Russia
Received December 19, 2002
EPR spectra of CH3, CH2D, CHD2, and CD3 radicals have been observed in H2 matrix in the temperature range 1.6-4.2 K. The radicals were obtained by condensation on a cold substrate of two gas flows: deuterium mixed with 2 mol % methane passed through a discharge and pure hydrogen avoiding the discharge. The CD3 and CHD2 spectra were found to be a superposition of two spectra: high-temperature and low-temperature. A transformation of the shape of CD3 and CHD2 spectrum with decreasing sample temperature was observed. This is attributed to a change in the populations of the lowest rotational states of the radicals. Compared to known results for deuterated methyl radicals in Ar, the present observations suggest an existence of a hindering barrier for the radical rotation in solid H2.