HIGH RESOLUTION LASER SPECTROSCOPIC STUDIES OF THE TRIPLET GROUND STATE, THE 23Πg STATE, AND THE COUPLED A~b STATES OF THE Rb2 DIMER MOLECULE

Abstract

The main focus of this work is using the infrared-infrared (IR-IR ) double resonance spectroscopic technique to study the 2³Πg, a³Σ⁺u triplet ground states, and the A¹Σ⁺u ~ b³Πu coupled states of the Rubidium dimer molecule. The initial analysis of the 2³Πg state involved separated analysis of the rotational and vibrational Bv and Gv functions to extract the molecular Dunham coefficients from the data. This was to avoid cross correlations between rotational and vibrational parameters because there was limited amount of rotational energy level data which included in addition perturbations between this state and other electronic states in the same region. An initial RKR potential energy curve was constructed based on this analysis. Subsequently this approach was augmented by a joint analysis of the 2³Πg state and the triplet ground state. This analysis was based on bound-free spectra, i.e. fluorescence from bound levels of the upper state to the continuum of the lower state. We present a comparison of these two approaches to the data analysis by testing the resulting potential energy functions through comparison of the calculated ro-vibrational energies against the observed energy level values The fluorescence from a discrete ro-vibrational level of the a bound upper state 2³Πg also includes transitions to discrete bound ro-vibrational levels of the triplet ground state (bound-bound emission). Accurate determination of the transition frequencies of the observed fluorescence spectroscopic lines allowed us to construct a reliable potential energy function that augmented our previous results on this state and corrected misinterpretation of that data in the literature. Similar infrared-infrared (IRIR) double resonance excitation of the 3¹Σ⁺g state was also used to observe resolved fluorescence spectra to the A~b states coupled by strong spin-orbit interaction. From the IRIR resolved fluorescence, we have filled the gap in the data range 12000cm-1 to 14000cm-1 of these coupled states for the Ω=0u⁺ component.