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A time-resolved electron spin resonance study of the hydrogen atom

Thesis/Dissertation ·
OSTI ID:6903940
A time resolved electron spin resonance investigation of the hydrogen atom has been carried out in a single radical system. An experimental apparatus has been constructed wherein experiments may be conducted simply and routinely on flowing solutions at pressures of up to one hundred atmospheres. The radicals were generated by the pulse radiolysis of triply distilled water and heavy water samples which were first saturated with nitrous oxide, then pressurized with hydrogen gas at one hundred atmospheres. In this way, the hydroxyl radical and the hydrated electron were both converted to hydrogen atoms within the microsecond time resolution of the spectrometer. The time dependence of the hydrogen atom signals, obtained at a range of initial radical concentrations and microwave power levels, were fitted using the Bloch equations modified to include electron spin polarization processes (CIDEP) and relaxation due to chemical reaction and spin exchange. The data were fitted to these equations using a non-linear least squares fitting routine. The rate constant used for the hydrogen atom self reaction was 1.55 {times} 10{sup 10} M{sup {minus}1} s{sup {minus}1}. The spin/lattice and spin/spin relaxation times are 30 {plus minus} 3 {mu}s, the rate of Heisenberg spin exchange was measured at 2k{sub HSE} = 6.2 {times} 10{sup 10} M{sup {minus}1} s{sup {minus}1}.
Research Organization:
Notre Dame Univ., IN (USA)
OSTI ID:
6903940
Country of Publication:
United States
Language:
English