Kinetic study of electronically excited lead atoms, Pb(61S0), by time-resolved absorption spectroscopy using attenuation of atomic resonance radiation

Abstract

A kinetic study of electronically excited lead atoms in the 6p²(¹S₀) state, 3.65 eV above the 6p²(³P₀) ground state, is presented. The optically metastable atoms were generated by the pulsed irradiation of tetraethyl-lead in the presence of excess helium buffer gas and monitored photoelectrically in absorption by attenuation of resonance radiation at λ= 500.5 nm (Pb(7s(¹P^°₁)→6p²(¹S₀))). The decay of the excited atom has been studied in the presence of a number of added gases. Second order quenching rate constants are reported for the following collision partners: Xe, H₂, O₂, N₂, CO, NO, CO₂, N₂O, CH₄, C₂H₄, C₂H₂, CF₄, SF₆ and Pb(C₂H₅)₄. The quenching data for a given molecule are compared with those of Pb(6¹D₂). The general collisional behaviour of the pair of states is discussed in relation to data for the low lying ¹D and ¹S states of the np² and np⁴ ground state configurations of other atoms in Groups IV and VI, respectively.