Laser Spectroscopic Studies of NaH and NaD Molecules

Abstract

Sodium hydride and sodium deuteride have been constantly studied by theorists and experimentalists for almost a century because it is one of the simplest molecules and therefore of fundamental interest For the NaH X 1Σ+ state which is also called the ground state a global fitting was performed and we obtained a new set of Dunham coefficients which has a higher accuracy and a wider available range of vibrational and rotational quantum numbers than the previous reports For the NaD molecule we utilized the stimulated emission pumping (SEP) spectroscopy of optical-optical double resonance (OODR) technique to investigate the NaD X 1Σ+ state Dunham coefficients vibrational and rotational constants dissociation limit and isotope shifts were determined and discussed The A 1Σ+ state which is also called the first excited state of the NaH molecule and that of the NaD molecule were studied using laser-induced fluorescence excitation spectroscopy We observed 839 transitions for the NaH molecule and 1404 transitions for the NaD molecule A global Dunham fitting was performed with all accessible data to deduce the Dunham coefficients Our results are compared with a given literature [J Chem Phys 142 044305 (2015)] The fluorescence due to the sodium dimer severely interfered on the NaH and NaD fluorescence collecting of the vibrational levels lying on the potential well of more than half well depth so that the vibrational levels of only up to v'NaH = 15 and v'NaD = 21 for the A 1Σ+ state were observed The NaH B 1Π state is lying on the near-dissociation region of the NaH A 1Σ+ state The laser-induced fluorescence excitation spectroscopy was also used in the B state investigation However the fluorescence interference due to the sodium dimer is quite severe in this energy regime so that a monochromator-PMT combination and a difference spectral analysis are used Only one vibrational level of the B 1Π state was observed and a series of PQR branches were identified The assignment of the rovibrational levels was made by comparing our experimental results with the ab initio calculation results reported by Aymar et al [Can J Phys 87 543 (2009)] The assignment of the rotational quantum number was made via the laser-induced fluorescence spectroscopy and the V-type OODR technique The dissociation energy and the molecular constants are also discussed

Date of Award	2018 Aug 31
Original language	English
Supervisor	Thou-Jen Whang (Supervisor)