Predissociation of the Na2 3 3Πg and other triplet states

Abstract

The Na2 3 3Πg state adiabatically dissociates to the 3s+4p atomic limit. The 3 3Πg levels below the 3s+3d atomic limit have been observed by perturbation facilitated optical–optical double resonance (PFOODR) fluorescence excitation spectroscopy. Energy levels above the 3s+3d atomic limit cannot be observed by detecting molecular fluorescence but are observable by detecting atomic 3d→3p fluorescence. The 3 3Πg state interacts with the 3s+3d 2 3Πg state. At lower energy this interaction is responsible for many perturbations between bound vibrational levels of these two states. Above the 3s+3d limit, as a result of this interaction, the 3 3Πg state is strongly predissociated and the linewidths of levels close to the 3s+3d limit are about 22 cm−1. The predissociation interaction is due to an avoided crossing between the adiabatic 2 3Πg and 3 3Πg states at R≈2.85 Å. Weak predissociation of the 4 3Σg+ and 2 3Δg states are also observed and discussed.

Analysis of the Na2 state above and below the 3s+3d atomic limit

“…The resulting simulated spectrum possessed a reasonable resemblance with the experimental spectrum [11], although, of course, peaks of the 4 3 R þ g predissociated lines as well as unassigned features were not reproduced. Later [22] additional spectra of the Na 2 2 3 P g $ 3 3 P g $ 4 3 R þ g predissociation were observed and simulated within the similar model and the similar characteristic quality, however, with a quite different computational method of the complex scaling (see [29][30][31]).…”

“…Liu et al [11] reported the first observation of the strong predissociation in the system Na 2 2 3 P g $ 3 3 P g $ 4 3 R þ g . Both 3 3 P g and 4 3 R þ g states dissociate to the 3s + 4p atomic limit, which is about 1100 cm À1 higher than the 3s + 3d dissociation limit of the 2 3 P g state.…”

“…The excitation spectra into the ro-vibrational levels above the 3s + 3d limit by detecting 3d fi 3p atomic fluorescence [11] (see Fig. 5 below), exhibited very wide overlapped profiles originating from the predissociation of the 3 3 P g levels, and narrower peaks embedded onto the latter ones originating from the predissociation of the 4 3 R þ g levels.…”

“…Later [22] additional spectra of the Na 2 2 3 P g $ 3 3 P g $ 4 3 R þ g predissociation were observed and simulated within the similar model and the similar characteristic quality, however, with a quite different computational method of the complex scaling (see [29][30][31]). In recent work [23] the method of the complex scaling was applied to simulate the spectrum of [11] using a more elaborated model including interactions with the 4 3 R þ g state. To finalize those efforts the fitting of the potential energy curves of the Na 2 2 3 P g ; 3 3 P g ; 4 3 R þ g states and other parameters ruling the process (interaction matrix elements, dipole moments) to the experimental data is needed.…”

The 23Δg State of 7Li2

“…(21) and (22). Natural lithium vapor was generated in a crossed heatpipe with about 1 Torr argon buffer gas.…”