Kinetics of neutral transition-metal atoms in the gas phase: oxidation reactions of titanium (a3F) from 300 to 600 K

Abstract

Gas-phase kinetics are reported for the reactions of Ti(a3F) with 0 2 , N20, NO, CO,, S02, and NO2 from 300 to 600 K. Titanium atoms were produced by the photolysis of T i c 4 at 248 nm and were detected by laserinduced fluorescence. Arrhenius expressions obtained for these reactions at a buffer gas pressure of 20 Torr are k(O2) = (1.69 f 0.41) X exp(-(14.3 f 0.9 kJ/mol)/RTcm3 s-l, k(N0) = 3.28 f 0.69) X exp(-(3.62 f 0.71 kJ/mol)/RT) cm3 s-l, k(CO2) = (7.0 f 1.6) X exp(-(2.66 f 0.64 kJ/mol)/RT) cm3 s-l. The rate constant of Ti with NO2 was found to be temperature independent from 300 to 500 K with a value of (9 f 4) X cm3 s-l. Quoted uncertainities are f2u. With the exception of Ti + 0 2 , all reactions were investigated as a function of pressure. Only the reactions of Ti with NO and C02 were found to depend on the argon buffer gas pressure. Termolecular rate constants at 300 Kweredeterminedtobe(5.8 f 2.6) X 10-31cm6s-1 and(3.5 f 1.0) X 10-32cm6s-1 forNOandCO2,respectively. exp(-(11.6 f 0.8 kJ/mol)/RT) cm3 s-l, k(N2O) = (1.74 f 0.44) X exp(-(14.9 f 0.8 kJ/mol)/RT) cm3 s-l, and k(SO2) = (1.70 f 0.33) X

Kinetics of the Sn(3P0) Reactions with CO2 and O2 over Wide Temperature Ranges

“…The product of the two preexponential terms of eq 4 is on the order of 10 -10 cm 3 molecule -1 s -1 , similar to that of the discussed metal atom CO 2 reactions and other well-studied metal atom O 2 exothermic spin-allowed reactions, i.e., those of Al, 20 Ba, 21 , V, 22 Ti, 27 and Ge. 28 For all these O 2 reactions the barrier is small (j10 kJ mol -1 ), again similar to CO 2 reactions of that nature.…”

Depletion Kinetics of Mo(a7S3,a5S2,a5DJ) by N2, SO2, CO2, N2O, and NO

“…1,2,14 The resonance interaction model is inconsistent in explaining the rate constants for the reactions of Mo (and Cr and W) with N 2 O. Bimolecular reaction kinetics are observed for the reactions of Mo(a 7 S 3 ) with SO 2 and N 2 O, termolecular reaction kinetics with NO, and no reactions with CO 2 .…”

“…∆H 298 ) -103 kcal/mol 17 (13) k(T) ) (5.2 ( 1.1) × 10 -12 T 1/2 × exp[-(9.3 ( 0.2 kcal mol -1 )/RT] cm 3 s -1 (14) Mo(a 5 S 2 ) interacts with N 2 O at the collision rate. The chemical reaction in which Mo(a 5 S 2 ) orbitally correlates with MoO(X 5 Π r ), may be operative.…”

Depletion kinetics of low-lying states of tungsten in the presence of NO, N2O, and SO2

“…character [4]. Experiments with vanadium [6], titanium [3,7], molybdenum [2,17], and niobium [25] have been performed recently which generally support this model.…”