Reaction dynamics of Al+O2→AlO+O studied by the crossed-beam laser-induced fluorescence technique

Abstract

Reaction dynamics of Si ( P J 3 ) + O 2 → Si O ( X Σ + 1 ) + O studied by a crossed-beam laser-induced fluorescence techniqueDynamics of the reaction, AlϩO 2 →AlOϩO, was studied by using the crossed-beam technique at five collision energies from 6.9 to 25.3 kJ/mol. The Al atomic beam was generated by laser vaporization and crossed with the O 2 beam at a right angle. The product AlO was detected by laser-induced fluorescence of the AlO(B 2 ⌺ ϩ -X 2 ⌺ ϩ ) transition and the rotational-vibrational distributions were determined. The observed rotational and vibrational distributions displayed greater populations in lower vibrational and rotational levels than expected statistically. Rotational distributions were also determined for two spin-orbit states of Al, Al( 2 P 1/2 ) and Al( 2 P 3/2 ), at two collision energies. At a collision energy of 12.2 kJ/mol, the higher energy spin-orbit excited state, Al( 2 P 3/2 ), showed lower reactivity, i.e., about one-third of the ground spin-orbit state, Al( 2 P 1/2 ). However, the rotational distributions for the two states were almost identical. Both the reactivity and rotational distributions for Al( 2 P 1/2 ) and Al( 2 P 3/2 ) became similar at a higher collision energy, 18.5 kJ/mol. These results suggest that the reaction of Al with O 2 proceeds via an intermediate complex.Both spin-orbit states lead to the complex, lose memory of the initial electronic state, and provide identical rotational distributions.

The harpooning mechanism as evidenced in the oxidation reaction of the Al atom

“…From the integration of speed distributions in AlO( N = 51) and the population of Al states, we obtained a relative state reactivity of σ (Al( 2 P 1/2 ))/ σ (Al( 2 P 3/2 )) = 1.5 ± 0.3, which is half of the ratio obtained at a similar E c via LIF. 23 , 24 A direct comparison between the present results and the previous LIF results shall be made with caution. We only observed the difference in the reactivity of two spin–orbit levels of Al ( 2 P 1/2 and 2 P 3/2 ) at high rotational levels of the AlO products, whereas LIF studies gave the reactivity difference in an all-states-integrated manner.…”

Reaction dynamics of V(aFJ4)+NO→VO(XΣ−4)+N studied by a crossed-beam laser-induced fluorescence technique

“…27 Briefly, the apparatus consisted of three chambers which were differentially pumped. 27 Briefly, the apparatus consisted of three chambers which were differentially pumped.…”

“…21 However, this mechanism could not predict the order of rate constants of the first row transition metal atoms, Sc, Ti, and V. Since the ground states of these atoms have 3d n−2 4s 2 ͑where n is the number of valence electrons͒ configurations which do not correlate with the ground states of metal oxides, the oxidation reactions for the ground states require potential barriers resulting from avoided intersections of the repulsive surfaces evolving from the ground states with the surfaces evolving from excited states of atoms having 3d n−1 4s 1 configurations. [24][25][26][27][28] Product states and/or angular distributions measured under single collision condition provide direct information about the mechanism. 22 However, the actual ordering of the measured rate constants for a given OX is k͑Ti͒ Ͻ k͑V͒ Ͻ k͑Sc͒.…”

Reaction dynamics of Mo + O2 → MoO + O studied by a crossed-beam velocity map imaging technique

“…32,33 Molybdenum atoms were generated by laser vaporization, and were issued as an atomic beam by carrier gas flow expanded through a pulsed nozzle (Jordan PSV, 1.0 mm diameter). Several carrier gases were used; the velocities of the Mo atom and the collision energies are summarized in Table I.…”