| Summary: | 碩士 === 國立成功大學 === 化學系碩博士班 === 101 === In this study, we investigated the fluorescence spectrum to explore the first excited singlet state A1Σ+ and the ground state X1Σ+ of NaD by laser excitation and laser induced fluorescence.
In the first part, the fluorescence spectra produced by stimulated absorption from ground state X1Σ+ to the first excited A1Σ+ state of NaD molecule were recorded. Five different dyes: LDS 759 (pumped by the second harmonic 532 of Nd:YAG laser), Exalite 392E, Exalite 400E, Stilbene 420, and Coumarin 440 (pumped by the third harmonic 355 of Nd:YAG laser), were used to produce laser wavelength in the range from 370 to 434 nm. A total of 688 transitions were collected and assigned to the rovibrational quantum numbers of v’=5~19, J’=0~24. The quantum number assignment was confirmed by laser-induced fluorescence spectroscopy. According to the signals recorded in the experiment, the vibrational terms (Gv), the rotational constant (Bv), and the centrifugal distortion constant (Dv) were determined for each rovibrational level. A set of Dunham coefficients, and RKR potential curve for A1Σ+ state of NaD are generated and the accuracy is improved compared to the previous literature reports.
In the second part, the laser induced emission signals of NaD molecule relaxed from the intermediate state (A1Σ+(v’,J’)) to ground state (X1Σ+(v”=14-15, J”)) by optical-optical double resonance fluorescence depletion spectroscopy were recorded. The spectra were taken in the laser wavelength of (621~626 nm (v”=14) and 643~649 nm (v”=15)) which were produced by DCM dye. A total of 28 rovibrational transitions were collected and assigned to the rovibrational levels v”=14 and 15, J”=3~11. According to the signals detected in the experiment, the vibrational term (Gv), and the rotational constant (Bv) of vibrational levels v”=14 and 15 were determined in the X1Σ+ state of NaD.
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