Kinetic studies of ground state tin atoms, Sn[5p2(3P0)], by resonance line absorption

Abstract

We present a kinetic study of ground state tin atoms, Sn[5p²(³P₀)], by atomic resonance absorption spectroscopy [λ= 286.33 nm, 6s(³P⁰₁)â†� 5p²(3P₀)]. The transient atoms were generated by pulsed irradiation and monitored in the presence of various added gases, in the “single-shot” mode. The modified Beer–Lambert law {I_tr=I₀ exp [–ε(cl)^γ]} was employed to describe the resonance absorption where γ was determined empirically as γ= 0.66 ± 0.03. The reaction of Sn(5³P₀) with the molecules N₂O and CO₂ was studied as a function of temperature over the range from room temperature to 670 K. Removal of the atom in the presence of the molecules C₂H₄, C₂H₂ and NO was found to be characterised by kinetics which were third order overall. The following absolute rate data for the reaction of Sn(5³P₀) with various gases are reported: second order (k_R, cm³ molecule^–1 s^–1): O₂(2.1 ± 0.1 × 10^–11), D₂(< 2 × 10^–14), CH₄(< 4 × 10^–15), CF₄(6.5 ± 0.5 × 10^–15), SF₆(2.2 ± 0.8 × 10^–15), SnMe₄(2.1 ± 0.3 × 10^–11)(T= 3000 K), CO₂(⩽ 2 × 10^–17, T= 567K); second order as ƒ(T): N₂O (k= 4.4 ± 1.6 × 10^–13 exp [– 0.110 ± 0.012 eV/RT)]; third order (k_R, cm⁶ molecule^–2 s^–1, T= 300 K, M = He): C₂H₄(8.5 ± 2.2 × 10^–31), C₂H₂(1.1 ± 0.3 × 10^–29) and NO(5.1 ± 0.4 × 10^–30).