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High-temperature fast-flow reactors (HTFFR) were used to obtain the rate coefficients k1 (and their accuracies) for the reaction Al +CO2→AlO+CO. At 310, 490, 750, 1500, and 1880 K, k1 is found to be (1.5±0.6) ×10−13, (6.9±2.7) ×10−13, (1.6±0.7) ×10−12, (9.0±3.8) ×10−12, and (3.8±1.5) ×10−11, respectively (all in ml molecule−1 s−1 units). For this temperature range k1(T) may be expressed by the curve fitting equation k1(T) =2.5 ×10−13 T1/2 exp(−1030/T)+1.4×10−9 T1/2 exp(−14 000/T). The data also indicate a wall-oxidation process of zeroth order in [CO2] with γAl of 10−3 to 10−2, not measurably dependent on T. Factors affecting the accuracy of the measurements are discussed. Over the 310–750 K range k1(T) obeys an Arrhenius expression, with an activation energy of 2.6±1.3 kcal mole−1, which implies D(Al–O) ?122 kcal mole−1. Above 750 K, k1(T) increases much more rapidly with T. This behavior cannot be described on the basis of simple transition state theory alone; the most probable additional factors involved are the opening of a second reaction channel leading to AlO(A 2Π) and preferential reaction of Al with CO2 in bending modes.

Metal atom oxidation reactions have been studied over about the 300-2000-K temperature range. The factors determining the currently achievable accuracy of 40-70% for the overall rate coefficient measurements of such reactions are discussed. Particular consideration is given to the influences of the systematic uncertainties involved in temperature determinations and in the flow profile (reaction time) factor at the relatively high pressures and average gas velocities required for the kinetic measurements. Compared to most regular flow tube studies of nonrefractory species the use of these higher T, P, and 0 has an adverse effect on accuracy; however, it is also shown that the higher T and P increase the accuracy of relative and absolute atom concentration determinations by atomic absorption measurements.

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.