The doubly excited 1 3Σ−g state of 7Li2

Abstract

This paper reports the first experimental observation of the doubly excited valence (2p+2p)3Σ−g state of 7Li2. We used cw perturbation-facilitated optical–optical double resonance (PFOODR) fluorescence excitation and resolved fluorescence spectroscopic techniques. All the observed levels have been detected through perturbations by the 2 3Πg state. The deperturbed primary molecular constants of this 1 3Σ−g state are Te=34 045.354(43) cm−1, ωe=216.820(37) cm−1, Be=0.673 69(47) cm−1, Re=2.670 81(94) Å, and De=4279.306(43) cm−1. The equilibrium internuclear distance of the 1 3Σ−g state is smaller than that of the X 1Σ+g ground state.

Strongly bound doubly excited states of Be2

“…Similar behaviour is shown by other diatomics with less than 4 VEs, e.g., the states 14&-(ugnu2) of Be,' (21) and 13Cp-(n:) of Li, (29). In all these cases, the lowest dissociation channel in which both atoms are s + p excited (a precondition for generating doubly excited states u2 + n :…”

“…Besides 1 'n,(A) of Be, (observed in emission), a few other SBDES cases are also experimentally known, namely 13Cg-(a: + n : ) of Li (29), 23rIu(a,2 + a',n,) of B, (16, 17,20, of C, (15,18,19,33,34). These doubly excited states have been detected either indirectly via perturbations (13C; -2 3~g in Li,) or directly via emission or absorption spectroscopy (B,, C,+, C,).…”

Quantum Control of the Spin-Orbit Interaction Using the Autler-Townes Effect

“…In the absence of a control field, the nominally singlet (triplet) level has 87% singlet (triplet) and 13% triplet (singlet) character, determined using the ratios of the intensities from OODR laser excitation scans of the triplet and singlet peaks as described in [19]. The 1 3 Σ − g electronic state has negligible hyperfine structure [20], and thus the predominantly triplet state 1 3 Σ − g (v=1, N =21, f ) can be considered to be a single level in the analysis. The 7 Li 2 dimers were generated in a heat pipe oven loaded with Lithium metal heated to a temperature of 850 K (estimated from the Doppler linewidth of a single laser excitation).…”

The Predissociation of the 13Σ−g State of 7Li2

“…With continuous-wave (CW) PFOODR spectroscopy, the 2 3 ⌸ g -1 3 ⌺ g Ϫ (v ⌸ , v ⌺ ) ϭ (26, 0), (29,2), (35, 6), (41, 10) perturbations were observed through A 1 ⌺ u ϩ v ϭ 13-b 3 ⌸ u v ϭ 19 mixed intermediate window levels. With a band-by-band deperturbation method, deperturbed molecular constants of the 1 3 ⌺ g Ϫ state were obtained for v ϭ 0 -10 (2).…”

“…Theoretical calculations of the potential curve of the 1 3 ⌺ g Ϫ state (2,5) and the transition dipole moment between the 1 3 ⌺ g Ϫ and b 3 ⌸ u states (6, 7) of Li 2 have been reported. The transition dipole moment, (R), ranges from 1.8615 to 2.3602 atomic units (a.u.)…”