This paper reports the experimental observation of the 2 3Σ+g, 3 3Σ+g, and 4 3Σ+g states of 7Li2 by cw perturbation facilitated optical–optical double resonance spectroscopy. Molecular constants and RKR potential curves have been obtained. Our experimental Te and Re for the 2 3Σ+g state are 27 297.45(16) cm−1 and 3.0797(18) Å, respectively, and for the 3 3Σ+g state are 31 043.93(53) cm−1 and 3.0378(19) Å, respectively. The above values are in very good agreement with theoretical calculations. Hyperfine splitting for both states has been resolved. Both states follow Hund’s case (bβS) hyperfine coupling scheme. The experimental Fermi contact parameter, bF, is approximately 96±2 MHz for the 2 3Σ+g state and 95.6±3 MHz for the 3 3Σ+g state. These values are in good agreement with the previously obtained value 98.6±4 MHz [Li et al., J. Chem. Phys. 96, 3342 (1992)]. One level of the 4 3Σ+g state has been observed and its hyperfine structure has been resolved and characterized with Hund’s coupling case (bβS).

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.

Articles you may be interested inHyperfine structures of the 7Li2 b 3Π u , 23Π g , and 33Π g states: Continuous wave perturbation facilitated optical-optical double resonance spectroscopy Perturbation facilitated optical-optical double resonance spectroscopy of the 23Σ+ g , 33Σ+ g , and 43Σ+ g Rydberg states of 7Li2 A pulsed optical-optical double resonance study of the 11Π g state of 7Li2The (2pϩ2p) 2 3 ⌸ g and (2sϩ3 p) 3 3 ⌸ g states of 7 Li 2 have been studied both experimentally and theoretically. Vibrational levels vϭ0 -41 of the 2 3 ⌸ g state and vϭ6 -10 of the 3 3 ⌸ g state have been observed by perturbation facilitated optical-optical double resonance ͑PFOODR͒ spectroscopy. Our ab initio calculations show that the 2 3 ⌸ g state, although dissociating into 2 pϩ2 p atomic limit, is a Rydberg state and strongly mixed with the (2sϩ3p) 3 3 ⌸ g and (2sϩ3d) 4 3 ⌸ g Rydberg states. Our theoretical calculations show good agreement with our experimental results.

To minimize ion bombardment induced damage in NF3-based chamber cleaning plasmas, we have studied the effects of diluent gases and reactor pressure on ion energy distribution functions in NF3 plasmas. We have utilized plasma ion mass spectrometry, ion energy analysis, and optical emission spectroscopy in 25 mol % NF3 plasmas with argon, helium, and oxygen diluents. We have also compared the NF3-based plasma measurements to those of 50 mol % C2F6/O2 plasmas. We have demonstrated that diluting with helium and operating at higher pressures will reduce ion energies in NF3 plasmas while maintaining superior chamber cleaning performance. In addition, we have correlated the intensity ratio of specific argon emission lines to average ion energies at the grounded electrode. This correlation provides a practical diagnostics tool for further optimization work.

Resolved fluorescence from the K2 43 Σ+g state to the a3 Σ+u state has been measured by the perturbation-facilitated optical–optical double resonance (PFOODR) technique. Data have been fit to an improved set of molecular constants for the a3 Σ+u state. In particular, the new Te value for this state has been determined as 4197.935±0.047 cm−1, nearly 1.8 cm−1 higher than previously reported. By combining the new results for the a3 Σ+u state and the recent results for the ground X1 Σ+g state [J. Chem. Phys. 103, 3350 (1995)], we report in this paper an improved analysis of long-range dispersion and exchange interactions between two K atoms and of the X1 Σ+g and a3 Σ+u state dissociation energies De of 4450.674±0.072 cm−1 and 252.74±0.12 cm−1, respectively.