Excitation of the O2(athinsp;1Dgr;g) state by low energy electrons

摘要

Coefficients for the excitation of theathinsp;1Dgr;gmetastable state of O2by low energy electrons in O2ndash;Ar mixtures have been measured using a drift tube technique. The time dependence of the absolute intensity of the 1.27 mgr;m band emission was measured for 1percnt; and 5percnt; O2in Ar at total gas densities of (1ndash;20)times;1024mminus;3. The electric field to gas density ratioE/Nwas varied from (0.3ndash;10)times;10minus;21Vthinsp;m2, corresponding to calculated mean electron energies between about 0.8 and 4 eV. The measured decay constants yield a normalized diffusion coefficient for O2(athinsp;1Dgr;g) in Ar of (2.8plusmn;0.2)times;1020mminus;1thinsp;sminus;1and a rate coefficient for quenching by O2of (1.57plusmn;0.1)times;10minus;24m3thinsp;sminus;1. Our experimental electron excitation coefficients agree satisfactorily with values calculated using previously derived sets of electron collision cross sections for O2and Ar.