Mode Specificity Study in Unimolecular Dissociation of Nonrotating H<sub>2</sub>O, DHO, and MuHO Molecules

Llanio-Trujillo, J. L.; Marques, Jorge M. C.; Varandas, A. J. C.

doi:10.1021/jp992461g

Cited by 2 publications

(1 citation statement)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results suggest that the intramolecular vibrational mode coupling is modest, leading to marked mode specific effects. These sorts of mode specific effects have been observed in other systems 53,54 and seem to depend on the extent of mode coupling to the reaction coordinate.…”

Section: Mode Specificitysupporting

confidence: 53%

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Martı́nez-Núñez

Vázquez

Varandas

2001

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Classical dynamics calculations are reported for the lowest energy unimolecular reaction channels of HSO.A recently published single-valued DMBE potential energy surface for HSO was employed in the dynamics calculations. The results predict that the isomerization channel HSO ! HOS is the preferred one at the lowest energies of the study, while dissociation to give H+SO is increasingly important as the energy rises. For the energies selected, the vibrational coupling is not strong enough to keep the phase space uniform during the unimolecular dynamics. In addition, strong mode specific effects were found under initial excitation of the three normal modes of vibration. The product energy distributions obtained with classical and quasi-classical barrier sampling techniques are very similar. The results predicted by EMS (with and without ZPE restrictions) initialization at the barrier show a much higher vibrational energy content of the products than those obtained by the above sampling techniques. This arises from the separability of the reaction coordinate mode inherent to the QCBS and CBS models.

show abstract

Section: Mode Specificitysupporting

confidence: 53%

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Martı́nez-Núñez

Vázquez

Varandas

2001

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

Termolecular kinetics for the Mu+CO+M recombination reaction: A unique test of quantum rate theory

Pan

Arseneau

Senba

et al. 2006

The Journal of Chemical Physics

View full text Add to dashboard Cite

The room-temperature termolecular rate constants, k0, for the Mu + CO + M<==>MuCO + M (M = He, N2, Ar) recombination reaction have been measured by the muSR technique, and are reported for moderator gas pressures of up to approximately 200 bar (densities less, similar 0.4 x 10(22) molec cm(-3)). The experimental relaxation rates reveal an unusual signature, in being dominated by the electron spin-rotation interaction in the MuCO radical that is formed in the addition step. In N2 moderator, k0 = 1.2+/-0.1 x 10(-34) cm(6) s(-1), only about 30% higher than found in Ar or He. The experimental results are compared with theoretical calculations carried out on the Werner-Keller-Schinke (WKS) surface [Keller et al., J. Chem. Phys. 105, 4983 (1996)], within the framework of the isolated resonance model (IRM). The positions and lifetimes of resonance states are obtained by solving the complex Hamiltonian for the nonrotating MuCO system, using an L2 method, with an absorbing potential in the asymptotic region. Accurate values of the vibrational bound and resonance states of MuCO reveal unprecedented isotope effects in comparisons with HCO, due to the remarkable effect of replacing H by the very light Mu atom (m(Mu) approximately (1/9)m(H)). Due to its pronounced zero-point energy shift, there are only two (J = 0) bound states in MuCO. Contributions from nonzero J states to the termolecular rate constants are evaluated through the J-shifting approximation, with rotational constants evaluated at the potential minimum. The value of the important A constant (181 cm(-1)) used in this approximation was supported by accurate J = K = 1 calculations, from which A = 180 cm(-1) was obtained by numerical evaluation. The calculations presented here, with a "weak collision factor" beta c = 0.001, indicative of the very sparse density of MuCO states, give a very good account of both the magnitude and pressure dependence of the experimental rates, but only when the fact that the two initially bound (J = 0) states become resonances for J > 0 is taken into account. This is the first time in IRM calculations of atom-molecule recombination reactions where J not equal to 0 states have proven to be so important, thus providing a truly unique test of quantum rate theory.

show abstract

Mode Specificity Study in Unimolecular Dissociation of Nonrotating H₂O, DHO, and MuHO Molecules

Cited by 2 publications

References 36 publications

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Termolecular kinetics for the Mu+CO+M recombination reaction: A unique test of quantum rate theory

Contact Info

Product

Resources

About

Mode Specificity Study in Unimolecular Dissociation of Nonrotating H2O, DHO, and MuHO Molecules

Cited by 2 publications

References 36 publications

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Unimolecular reaction dynamics of HSO. Analysis of the influence of different barrier samplings on the product energy distributions

Termolecular kinetics for the Mu+CO+M recombination reaction: A unique test of quantum rate theory

Contact Info

Product

Resources

About

Mode Specificity Study in Unimolecular Dissociation of Nonrotating H₂O, DHO, and MuHO Molecules