Activation of the CH stretching vibrations in CH4–OH entrance channel complexes: Spectroscopy and dynamics

Abstract

Articles you may be interested inMode-selective O-H stretching relaxation in a hydrogen bond studied by ultrafast vibrational spectroscopy J. Chem. Phys. 125, 074504 (2006); 10.1063/1.2219111 Comparing the dynamical effects of symmetric and antisymmetric stretch excitation of methane in the Cl + CH 4 reaction J. Chem. Phys. 120, 5096 (2004); 10.1063/1.1647533 OH vibrational activation and decay dynamics of CH 4 -OH entrance channel complexes Intermolecular interaction in the CH 3 + -He ionic complex revealed by ab initio calculations and infrared photodissociation spectroscopy J. Chem. Phys. 110, 9527 (1999); 10.1063/1.478917 Structures and the vibrational relaxations of size-selected benzonitrile-( H 2 O ) n=1-3 and -( CH 3 OH ) n=1-3 clusters studied by fluorescence detected Raman and infrared spectroscopiesThe vibrational spectroscopy and decay dynamics of CH 4 -OH reactant complexes have been studied in the CH 4 symmetric and antisymmetric stretching regions ( 1 and 3 ). The vibrational spectra have been obtained using both infrared and stimulated Raman excitation with ultraviolet probe laser-induced fluorescence detection. Stimulated Raman excitation of CH 4 -OH in the symmetric stretching region reveals two blended Q branch features at 2912.5 and 2911.8 cm Ϫ1 . An extremely weak infrared spectrum is also seen in the CH 4 symmetric stretching region, which is induced by the presence of the nearby OH partner. Infrared excitation in the asymmetric stretching region results in an intense, yet enormously broad spectrum centered at 3020 cm Ϫ1 that extends over 40 cm Ϫ1 . The appearance of the spectra in the 1 and 3 regions has been explained in terms of a model in which the CH 4 unit undergoes internal rotation within the CH 4 -OH complex. The 1 features are attributed to transitions involving two different nuclear spin states of CH 4 . In the 3 region, the CH 4 -OH complex can undergo a multitude of allowed transitions, each associated with a rovibrational transition of free methane, which give rise to the enormous span of the spectrum. The vibrational spectra also exhibit extensive homogeneous broadening ͑у1 cm Ϫ1 ͒ arising from the rapid decay of vibrationally activated CH 4 -OH complexes due to vibrational predissociation and possibly reaction. The OH fragments are produced with minimal rotational excitation, indicating that the dominant inelastic decay channel involves near-resonant vibrational energy transfer within the CH 4 unit from the initially prepared CH stretch to an overtone bend (2 4 ) state.

Six-dimensional and seven-dimensional quantum dynamics study of the OH + CH4 → H2O + CH3 reaction

“…These measurements also indicated that vibrational activation of OH is effective in promoting reaction with CH 4 , contrary to a OH role as a spectator in the early dynamics calculations of OH + CH 4 . 9 Lester et al 10,11 investigated the vibrational spectroscopy and decay dynamics of CH 4 -OH complexes through an infrared-ultraviolet double-resonance technique. Recently, Liu et al [12][13][14] studied the product correlated state-to-state dynamics for the OH + CD 4 reaction using the three-dimensional ion-velocity-imaging technique in combination with (2 + 1) resonance-enhanced multiphoton ionization (REMPI) detection of the CD 3 product.…”

Communication: An accurate full 15 dimensional permutationally invariant potential energy surface for the OH + CH4 → H2O + CH3 reaction

“…[13][14][15] Furthermore, the vibrational spectroscopy and decay dynamics of the CH 4 -OH complex in the entrance channel have been studied by Lester and co-workers. 16,17 a) Authors to whom correspondence should be addressed. Electronic addresses: jli15@cqu.edu.edu and hguo@unm.edu…”

Second-order Møller–Plesset perturbation theory without basis set superposition error. II. Open-shell systems

“…It has recently been studied 22,23 as a possible entrance channel complex for the hydrogen abstraction reaction CH 4 ϩOH→CH 3 ϩH 2 O.…”