氣態氫化鈉分子X、A、C1Σ+能態的雷射光譜研究

Abstract

Using different spectroscopic methods, three electronic states, ground (X1Σ+), first excited (A1Σ+), and third excited (C1Σ+) states, of sodium hydride molecule NaH were investigated in this dissertation. The Excitation spectroscopy of the A1Σ+→X1Σ+ transitions of NaH has been analyzed in the wavelength range of 378–436 nm. The observed vibrational levels of the first excited state (A1Σ+) were from v′=3 to 12. A set of molecular constants has been obtained and Rydberg-Klein-Rees (RKR) potential curve has been constructed in this work. The dissociation energy of the ground state (X1Σ+) of NaH was determined by analyzing the observed near-dissociation rovibrational levels. These levels were detected by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the range 9≤v≤21 and 1≤J≤14 were assigned to the X1Σ+ state of NaH. The highest vibrational level observed was about 40 cm-1 to the dissociation limit of the ground state. One quasibound level, above the dissociation limit and confined by the centrifugal barrier, was observed. Using near dissociation theory, one can determine the vibrational quantum number at dissociation vD from extropalation of the highest four vibrational levels and yield the dissociation energy De=15815±5 cm-1. Based on the observed eigenvalues in this work and the available data from literature, a set of Dunham coefficients and the rotationless RKR curve were provided. The effective potential curve and the quasibound states were discussed. The outer well of the third excited state (C1Σ+) of NaH was determined using pulsed optical-optical double resonance fluorescence depletion spectroscopy. The level-selected fluorescence of the A1Σ+ state emitted to the ground state is depleted when a probe laser excites the molecules from A1Σ+ to C1Σ+ states. A total of 456 rovibrational levels, v=5-33 and J=1-11, were assigned to C1Σ+ state. A set of Dunham coefficients and the RKR potential curve for the outer well were reported.