Time-Resolved Measurements of the Gas-Phase Reaction of Mo2 (X 1Σg+) with Some Simple Molecules at Room Temperature

Abstract

A multiphoton dissociation (MPD) of volatile metal carbonyl was applied for pulse production of neutral transition metal dimers in a gas-phase kinetic study. Its feasibility was discussed in the reaction systems of Mo2 with small molecules (O2, CO, NO, H2, SF6, NH3, and C2H4). Some potential problems, such as disturbances to the dimer production mechanism from the reactant addition and to neutral reaction kinetics from ionic species inevitably produced in the MPD of metal carbonyls, were experimentally examined. The transient concentration of Mo2 (X 1Σg+, ν = 0) produced by 266-nm MPD of Mo(CO)6 was measured by a laser-induced fluorescence (LIF) at 518.60 nm (A 1Σu+, ν″ = 0 ← X 1Σg+, ν′ = 0). The pseudo-first order decay rates of Mo2 were found to increase with increasing the concentration of some reactive species (O2, NO, and NH3). Our results obtained from time-resolved measurements were found to be almost consistent with the observations of Lian et al. (J. Phys. Chem., 98, 11637 (1994)) who prepared Mo2 by laser vaporization and measured its depletion in a fast-flow reactor.