Ground- and excited-state properties of Li2 and Li2+ from ab initio calculations with effective core polarization potentials

Theoretical study of the absorption spectra of the lithium dimer

“…The calculated and measured lifetimes agree well up to about 4 500 cm −1 in agreement with the findings of Ref. [30]. From approximately 5 000 cm −1 and higher the experimental lifetimes slightly decrease relative to theory by about 0.8 ns or five percent, as demonstrated in Fig.…”

“…The dissociation energy for the A 1 Σ + u state is determined to be 9 352.194 cm −1 in our calculation, in good agreement with the experimental value [29] of 9 352.5(6) cm −1 given in Ref. [30].…”

“…3. We investigated whether the 2 1 Σ + g state might supply an additional spontaneous decay channel, but the theoretical value T e = 20 128 cm −1 [30] for this state appears to place its minimum at around 6 000 cm −1 relative to the minimum of the A 1 Σ + u state, apparently ruling this mechanism out. The reason for the significant downturn of experimental lifetimes for higher term energies is currently not understood; however, the overall excellent agreement between our calculated lifetimes and the measurements gives us confidence in our molecular data and calculational procedures.…”

Theoretical study of the photodissociation of Li2+ in one-color intense laser fields

“…43 As shown in Fig (m = 0) between υ = 15 and 17, so that dissociations starting from the levels that are energetically close to this region are expected to produce remarkable distributions of the fragments. A careful analysis of the results from previous theoretical study, 46 which are in excellent agreement with the available experimental data for the ground state, 53 shows that if one starts from a rovibrational level near υ = 13−14 of the ground state, with a relative energy of about 3400− 3500 cm −1 , several transitions can take place with almost the same photon energy. 43 Although an Li 2 + ion with these vibrational energy levels cannot be produced by infrared excitation from the υ = 0 level (i.e., due to the absence of a permanent dipole moment of the homonuclear diatomic molecule), it could be experimentally created through the photoionization of a single two-state rotational wave packet on the E 1 g + (υ E = 9, J E = 27, 29) state of Li 2 with the maximum coherent ionization signal.…”

“…In the theoretical studies of Li 2 + , Magnier et al 40 presented a wave packet simulation of ATD involving the resonant two-photon processes in which both the intermediate and the final states belong to the dissociative continuum and analyzed the interference phenomena and Rabi oscillations between the continuum states through one-color and/or two-color excitations; Khait et al 43 reported the field-free potentials and dipole transition moments of Li 43 dissociations starting from levels energetically close to this region are expected to produce remarkable distributions and reveal interesting behaviors for different channels with changing laser conditions. Analysis of the results from previous theoretical treatments 46 shows that if one starts with a rovibrational level near υ = 13−14 of the ground state, with a relative energy of about 3400−3500 cm −1 , several transitions can take place with almost the same photon energy. 43 Moreover, Li 2 + ions in such levels could be created experimentally through photoionization of a single two-state rotational wave packet on the E 1 g + (υ E = 9, J E = 27, 29) state of Li 2 with the maximum coherent ionization signal.…”