Reaction dynamics of C(1D)+H2(v)→CH(X 2Π)+H

Abstract

The CH(X 2Π,v,J,Ω,Λ) product state distribution from the reaction C(1D)+H2(v)→CH+H was determined by laser-induced fluorescence (LIF) where the B 2Σ–X 2Π transitions were probed. Most of the available energy is released as translation. A nearly thermal rotational distribution is obtained for CH(v=0,1). Only a small fraction, 4.1×10−4, of the CH products is formed in the vibrationally excited state. A higher propensity for the production of CH in the symmetric Π(A′) Λ sublevels is evident. For studying the influence of vibrational excitation on the reaction dynamics, H2 was excited to its first vibrational state via stimulated Raman pumping (SRP). H2(v=1) increases the reaction rate and enhances the population of higher rotational states, but diminishes the Λ selectivity. The vibrational population ratio P(v=0)/P(v=1) of the CH product remains unaltered. Insertion of the C(1D) atom into the H2 bond is the major reaction mechanism, but the probability for an abstractive process seems to increase when H2(v=1) is reacting with C(1D).

Quantum mechanical differential and integral cross sections for the C(1D) + H2(ν = 0, j = 0) → CH(ν′, j′) + H reaction

“…It can be seen that, most CH products are populated on the ground vibrational state, and only a few are populated on the ν ′ = 1 state, which is consistent with the experimental measurements. 14,15 The ICS (ν ′ = 1) has a visible contribution only at E c > 0.1 eV and then increases monotonically with the collision energy, whereas the ICS (ν ′ = 0) shows an opposite behavior. The product vibrational branching ratio defined as the ratio between the ICS (ν ′ = 1) and the ICS (ν ′ = 0) is 0.087 at the collision energy of 0.166 eV, which is consistent with the experimental value of 0.04.…”

“…Experimentally, a number of kinetic and dynamical studies on the title reaction and its isotopic variants have been reported, [10][11][12][13][14][15][16][17][18][19] including several crossed molecular-beam (CMB) experiments. [16][17][18][19] In particular, Casavecchia and coworkers 16,18 measured the product angular and velocity distributions for the C( 1 D) + H 2 reaction at the collision energies of 7.8 and 16.0 kJ mol −1 , and the thermal rate coefficients for the C( 1 D) + H 2 reaction and its isotopic variants have been measured by Sato et al 15 On the theoretical side, Bussery-Honvault et al have developed a global ab initio potential energy surface (BHL PES) for the singlet ground state (1 1 A ′ ).…”

Born–Oppenheimer quantum dynamics of the C(D1)+H2 reaction on the CH2 ã A11 and b̃ B11 surfaces

“…1,2 There have been experimental investigations of the C͑ 1 D͒ +H 2 reaction concerning the product internal energy distribution [3][4][5][6] and the kinetics. [6][7][8][9] In particular, the most recent experimental value 9 of the rate constant at 300 K is ͑2.0Ϯ 0.6͒ ϫ 10 −10 cm 3 s −1 .…”

Dynamical and stereodynamical studies of alkaline-earth atom–molecule reactions

“…Again, energy deposited in the v ¼ 1 vibrational level of H 2 may enhance the probabilities for the reaction pathways which are otherwise negligible in the H 2 (v ¼ 0) reactions [52]. Like this case, the vibrational excitation of H 2 helps open up new reaction pathways in the reactions with C( 1 D) and O( 3 P) [53,54] or increased rotational excitation of HD (v ¼ 1) in the reaction with D [25,55]. An active focus to find how energy is deposited and released was carried out in the Mg(3p 1 P) þ H 2 (v ¼ 1) reaction [24].…”

“…An active focus to find how energy is deposited and released was carried out in the Mg(3p 1 P) þ H 2 (v ¼ 1) reaction [24]. Hydrogen molecules in v ¼ 1, j ¼ 0-3 are prepared by using stimulated Raman pumping (SRP) [22][23][24][25][52][53][54][55].…”