sup 13 C and sup 1 H spin relaxation in CH sub 4 in the gas phase

摘要: The dominance of the spin-rotation mechanism in relaxation both {sup 13}C and 1}H nuclear spins 13}CH{sub 4} various buffer gases has been established. Cross sections for changes rotational angular momentum vector CH{sub molecules collisions with have obtained as a function temperature from measured spin times or both. At 300 K these cross are 18.8 {plus minus} 0.5 {angstrom}{sup 2} (CH{sub 4}-CH{sub 4}), 16.3 0.3 4}-N{sub 2}), 15.8 0.2 {angstrom} 4}-CO), 24 1 4}-CO{sub 15 4}-Ar), 18.3 0.6 4}-Kr), 22.4 4}-Xe), 4}-HCl), 25 4}-CF{sub 34.5 1.1 4}-SF{sub 6}), 24.0 0.8 4}-SiH{sub 4}).