Energy Transfer in Li*(3p)−H₂ Collisions

Abstract

The direct collisional energy transfer process Li*(3p) + H 2 f Li*(3s) + H 2 is investigated under gas cell conditions. In particular, we measured the nonreactive far-wing absorption profile of LiH 2 complexes by monitoring the Li(3s) f Li(2p) fluorescence at 812.6 nm. Strong satellite structures are observed at around 700 cm -1 in the blue wing and 162 cm -1 in the red wing of the LiH 2 profile. The experimental results are in agreement with ab initio theoretical predictions, which showed a strong probability of a diabatic transition making the 3p-3s quenching easy.

Energy transfer in Li(4p)+(Ar,H2,CH4) collisions

“…As was indicated previously, 46 the determining factor for the nonradiative transition probability in the LiH 2 case is the number of collisions between Li and H 2 . Indeed, the total transition probability is directly proportional to the number of collisions during the lifetime of each electronic state.…”

“…34,35,45,46 Studying molecular electronic states made from Li(4p) requires large and flexible basis sets to describe all electronic states below 4p and some electronic states above this. So we have done the atomic calculations to obtain an optimal basis to describe all the electronic states from Li(2s) to Li(5s).…”

Experimental studies of collisions of excited Li(4p) atoms with C2H4, C2H6, C3H8 and theoretical interpretation of the Li–C2H4 system

“…The details of the experimental setup have been described in previous works [20][21][22][23][24]. Briefly, the doubled and tripled frequencies of a 20-Hz Nd: YAG laser were used to pump two dye lasers simultaneously in a laser pump-probe arrangement for the studies involving reactive collisions.…”

“…Indeed, we have been unable to detect any LiH products for Li(3p) and Li(4p). The scattering technique, explained in detail in previous works [20][21][22][23][24], offers a direct probe of the continuum or ''scattering states" of a transient bimolecular collision complex. This technique can be used to selectively excite quasimolecular electronic states of well-defined symmetry corresponding to a specific electronic orbital alignment of the reagents within the transient reaction 0301-0104/$ -see front matter Ó 2008 Elsevier B.V. All rights reserved.…”

Quasiclassical trajectory calculations for Li(22PJ) + H2 → LiH(X1Σ+) + H: Influence by vibrational excitation and translational energy

“…29 For the lithium, all-electron 12s8p5d3f Gaussian type orbitals (GTOs) were contracted to (9s8p5d3f) atomic basis functions to optimally describe the 2s, 2p, 3s, 3p, and 4s atomic states. 30 The restricted HF energy of the hydrogen atom calculated with this basis is -0.499354 hartree. For the hydrogen atom, 5s2p GTOs were contracted to 4s2p atomic basis functions.…”