The 4pπ 3Πg–a 3Σu+ system in Ne220 and Ne222

Abstract

Excitation spectra for the 4pπ 3Πg–a 3Σu+ system in Ne220 and Ne222 have been used to characterize the v=0 through v=3 levels in both electronic states. This is the first time levels with v>1 have been characterized experimentally in either dimer. Rotational analyses lead to Be- and αe-values of 0.5638 cm−1 and −0.9000×10−2 cm−1 and of 0.5113 cm−1 and −0.6651×10−2 cm−1 for the a 3Σu+ states in Ne220 and Ne222, respectively. The Be- and αe-values are, respectively, 0.5716 cm−1 and −0.6429×10−2 cm−1 (20Ne2) and 0.5201 cm−1 and −0.4172×10−2 cm−1 (22Ne2) for the 4pπ 3Πg state. The vibrational parameters ωe, xωe are found to be 556.2, 10.2 cm−1, and 593.2, 7.5 cm−1 for the a 3Σu+ state and 4pπ 3Πg state, respectively, in Ne220 with corresponding values of 529.5, 9.75 cm−1, and 567, 7.5 cm−1 in Ne222. The observed vibrational level differences [ΔG(v+1/2)-values] for the 4pπ 3Πg state are within 0.5% of analogous spacings for the ground electronic state (X 2Σu+) of Ne2+ reported by Kim et al. [Phys. Rev. Lett. 68, 1311 (1992)].

CsAr, CsXe, and RbXe B2Σ1/2+ Interatomic Potentials Determined from Absorption Spectra and Calculations of Franck–Condon Factors for Free–Free Optical Transitions of Atomic Collision Pairs

“…For almost a century, the spectroscopy of diatomic molecules has largely been concerned with the analysis of vibrational–rotational transitions between strongly bound electronic states (i.e., D e ≫ kT , where D e is the dissociation energy, k is the Boltzmann’s constant, and T is the temperature). − Analysis of rotationally resolved spectra, in particular, allows for interaction potentials to be constructed accurately, and especially in the region of internuclear separation ( R ) in the vicinity of the equilibrium value ( R e ). − In contrast, observing and characterizing diatomic excited states having shallow potentials ( D e < kT ) or small barriers is challenging from both theoretical and experimental perspectives. Experimental spectra for free–free molecular transitions necessary to provide a rigorous test of calculations are sparse in the literature, and numerical simulations are hampered by energy resolution restrictions imposed by basis set limitations and approximations made for computational purposes (see, for example, refs and ).…”

Spectroscopic characterization of the potential energy functions of Ne2 Rydberg states in the vicinity of the Ne(1S0)+Ne(4p′) dissociation limits

“…The dimers are model systems for studying atomatom interactions [3] and represent a starting point to describe the properties of larger rare-gas clusters [4,5]. Several experimental and theoretical studies have been devoted to the ground and first excited singlet states of Ne 2 [6][7][8][9][10] and to its triplet Rydberg states [10][11][12][13][14][15][16][17][18][19][20], which were studied from the metastable a 3 R þ u state. The six low-lying electronic states of the Ne þ 2 ion have been studied by microwave electronic spectroscopy [21,22] and ab initio quantum chemistry [23].…”