HTFFR kinetics studies of Sn/N2O, a highly efficient chemiluminescent reaction

Abstract

High temperature fast-flow reactors (HTFFR) were used to study the Sn/N2O reaction from 300–950 K at pressures from 4 to 110 Torr. The observed emissions are SnO[a 3Σ+(1) –X 1Σ+] and (b 3Π–X 1Σ+). The photon yield of the former system is 0.53±0.26 independent of T, that of the latter (5.9±2.9) ×10−1 exp[−(1200±200)/T]. Comparison of the photon yields of N2O- in-excess experiments, where [Sn] is measured in absorption, to experiments where Sn is in excess allows determination of oscillator strengths for the ground electronic states of Sn: f[Sn(3P0) (286.4 nm)]=0.20±0.10 and f[Sn(3P1) (300.9 nm)]=0.052±0.026, in good agreement with literature values. At T≳950 K, emission from SnO(c–X 1Σ+) and (A 1Π–X 1Σ+) is observed, apparently due to N2O decomposition followed by Sn/O2 reaction. Quenching rate coefficients at ≈900 K for SnO (a) are determined to be kQN2(a)⩽2.3×10−16; kQAr(a)⩽4.0×10−16; kQN2O(a)⩽4.0×10−14; kQSn(a)⩽4.0×10−12 ml molecule−1 s−1 based on τrad(a)⩾2.5×10−4 s. For SnO (b) the data yield τbkQN2(b) =4.8×10−20; τbkQAr(b)⩽2.0×10−20; τbkQN2O(b)⩽1.0×10−17; τbkQSn(b)⩽1.0×10−15 ml molecule−1. The overall Sn(3P0)/N2O reaction (production of all states) proceeds with a rate coefficient (8.9±4.0)×10−13 exp [−(2260±180)/T] ml molecule−1s−1. Approximate overall rate coefficients are reported for Sn(3P1)/N2O, Sn(3P0)/NO2, and Sn(3P0,1)/O2.