A three-dimensional wave packet study of Ar⋅ ⋅ ⋅I2( B )→Ar + I + I electronic predissociation

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A calculation of the rovibronic energies and spectrum of the B ̃ A 1 1 electronic state of Si H 2 Dynamics of harpooning studied by transition state spectroscopy. II. LiFH Photodissociation of HOBr. I. Ab initio potential energy surfaces for the three lowest electronic states and calculation of rotational-vibrational energy levels and wave functions In this work the LiHF(A,B,BЈ←X) electronic spectrum is simulated and compared with the experimental one obtained by Hudson et al. ͓J. Chem. Phys. 113, 9897 ͑2000͔͒. High level ab initio calculations of three 2 AЈ and one 2 AЉ electronic states have been performed using a new atomic basis set and for a large number of nuclear configurations ͑about 6000͒. Four analytic global potential energy surfaces have been fitted. The spectrum involved very excited rovibrational states, close to the first dissociation limit, at high total angular momentum. Two different methods have been used, one based on bound state and the second one on wave packet calculations. Different alternatives have been used to simulate the relatively high temperatures involved. The agreement obtained with the experimental spectrum is very good allowing a very simple assignment of the peaks. They are due to bending progressions on the three excited electronic states. A simple model is used in which only rotational degrees of freedom are included, which simulates the spectrum in excellent agreement with the experimental one, providing a nice physical interpretation. Moreover, the remaining theoretical/experimental discrepancies have been attributed to nonadiabatic effects through the extension of this model to a diabatic representation of excited coupled electronic states.

Section: Nonadiabatic Effects and Interpretation Of The Spectrummentioning

confidence: 99%

Transition state spectroscopy of the excited electronic states of Li–HF

Aguado

Paniagua

Sanz-Sanz

et al. 2003

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“…22 Based on this model, the oscillations were reproduced by a simple golden rule treatment of the EP in a single dissociative electronic state yielding IϩIϩAr products. 49 In this interval, VP takes place by the transfer of three vibrational quanta and is mediated by Intramolecular Vibrational Redistribution ͑IVR͒. [45][46][47][48] Therefore, the monotonous increase of the VP rate with vibrational excitation assumed by Burke and Klemperer 22 can only be explained assuming the IVR statistical limit.…”

Section: Introductionmentioning

confidence: 99%

ArI 2 (X)→Ar+I 2 (B) photodissociation: Comparison between linear and T-shaped isomers dynamics

Roncero

Lepetit

Beswick

et al. 2001

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Quantum dynamical calculations on ArI 2 photodissociation have been performed using ab initio and semi-empirical potential energy surfaces, which support both linear and T-shaped isomers in the ground electronic state. Whereas the photon absorption spectra for the T-shaped isomer consist of narrow and intense bands, those for the linear isomer result from the superposition of a continuous background and peaks due to linear quasi-bound states. Vibrational distributions for the linear isomer are broader than those originating from the T-shaped one. Rotational distributions for the linear isomer are smooth and characteristic of a fast dissociation dynamics, whereas those for the T-shaped isomer are highly oscillatory. Implications of these results on the interpretation of experimental data are discussed.

“…The oscillations of the EP rate were confirmed theoretically using a time dependent Golden rule treatment for EP. 5 However, this simple picture of the VP/EP competition was challenged when it was realized that the VP dynamics occurs by the transfer of two or three vibrational quanta via intramolecular vibrational energy relaxation ͑IVR͒ in the sparse-intermediate regime, 6 yielding VP rates which oscillate more drastically than the EP rates. This was later confirmed by full quantum wave packet calculations 7,8 on the competition between VP and EP dynamics, as recently reviewed.…”

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confidence: 99%

Communications: A model study on the electronic predissociation of the NeBr2 van der Waals complex

Sanz-Sanz

Roncero

Hernández‐Lamoneda

et al. 2010

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Recently, the predissociation lifetimes of the NeBr2(B) complex for different initial vibrational excitation (10≤v′≤20) have been measured using time-resolved optical pump-probe spectroscopy [Taylor et al., J. Chem. Phys., 132, 104309 (2010)]. In the vibrational interval studied, the vibrational predissociation (VP) proceeds by the transfer of a single vibrational quantum and the lifetimes are expected to decrease smoothly with increasing v′, as predicted by the energy gap law. However, the experimental lifetimes show strong oscillations with v′, which were attributed to the occurrence of electronic predissociation into two possible dissociative electronic states of Br2(1g,2g), based on a Franck–Condon spectator model. In this work we reproduce the experimental findings by performing full three-dimensional wave packet calculations for the competition of vibrational and electronic predissociation, including the B(0u+), 2g, and C(1u) electronic states. Model potential energy surfaces were used based on previous theoretical simulations of the VP dynamics on the B state and on ab initio calculations on the NeCl2 related system. Thus, only two parameters, the strength of the electronic couplings, are fit to achieve the excellent theoretical/experimental agreement.