High temperature reaction of Sn(3P0) atoms with O2 based on Sn- and O-concentration measurements

Abstract

The reaction of Sn(³P₀) atoms with O₂ has been studied over the temperature range 1300 to 2250 K and the total density range 2.5 × 10¹⁸ to 5.4 × 10¹⁸ molecules cm⁻³ by using a shock tube equipped for atomic resonance absorption spectroscopy (ARAS). Tetramethyltin was used as a precursor of Sn(³P₀) atoms. The overall rate coefficient was determined from the pseudo-first-order decay of Sn(³P₀) atoms to be k(Sn + O₂) = 10^{−9.41 ± 0.03} exp[ − (11.5 ± 1.1) kJ mol⁻¹/RT] cm³ molecule⁻¹ s⁻¹ (error limits at the two standard deviation level). This result is in good agreement with previous data of Fontijn and Bajaj (J. Phys. Chem., 1996, 100, 7085), but about twice that of Zaslonko and Smirnov (Kinet. Catal., 1980, 21, 602). To examine the product channel of the Sn(³P₀) + O₂ reaction experimentally, O-atom ARAS measurements were performed. Two types of O-profiles were found, one reaching a peak around 40 μs and the other displaying a two-step increase, depending on the composition of the mixtures. When the reaction channel for forming O(³P) atoms was assumed, numerical calculation was found to reproduce both these measured profiles, demonstrating that the main products are SnO(X¹Σ⁺) and atomic O(³P).