Abstract
The non-adiabatic state-to-state dynamics of the Li(2p) + H2 → LiH + H reaction has been studied using the time-dependent wave packet method, based on a set of diabatic potential energy surfaces recently developed by our group. Integral cross sections (ICSs) can be increase more than an order of magnitude by the vibrational excitation of H2, whereas the ICSs are barely affected by the rotational excitation of H2. Moreover, ICSs of the title reaction with vibrationally excited H2 decrease rapidly with increasing collision energy, which is a typical feature of non-threshold reaction. This phenomenon implies that the title reaction can transformed from an endothermic to an exothermic reaction by vibrational excitation of H2. With the increase of the collision energy, the sideways and backward scattered tendencies of LiH for the Li(2p) + H2(v = 0, j = 0, 1) → LiH + H reactions are enhanced slightly, while the backward scattering tendency of LiH for the Li(2p) + H2(v = 1, j = 0) → LiH + H reaction becomes remarkably weakened. For the reaction with vibrationally excited H2 molecule, both direct and indirect reaction mechanism exist simultaneously.
Highlights
In order to conveniently analyze dynamic results within the framework of potential energy surfaces (PESs), the schematic energy diagram of the title reaction is presented in Fig. 1 according to the HYLC PESs
The reaction probabilities of the reaction with different rovibrational states of the H2 molecule and total angular momentum quantum numbers are depicted in Fig. 2 as a function of the collision energy
The influence of the rovibrational excitation of H2 molecule on the Li(2p) + H2 → LiH + H has been investigated using a set of diabatic PESs constructed by our group[22]
Summary
The reaction involving alkali atoms and H2 molecule have been studied for decades[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. Bililign et al.[11] applied the “half-collision” pump-probe technique to measure the far-wing absorption profiles of NaH2 collision complex in the Na(42P) + H2 reaction In this experiment, the rotational state distributions of product NaH were observed. Bililign et al.[17] studied the Li(2p) + H2 → LiH + H reaction using the laser pump-probe far-wing scattering technique; the LiH product was observed when the collision energy was sufficiently high for the product formation. They found that reactive collisions take place preferentially in bent structure (near C2v geometry). In order to get detailed information on the influence of rovibrational excitations on the Li(2p) + H2 → LiH + H reaction, the state-to-state dynamic of this reaction has been studied based on the HYLC PESs
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