| An account of experimental optical spectroscopy study on three 3d transition-metal containing radicals, i.e. CuCl, NiS, and FeS, are presented in this thesis. The involving radicals are produced in a supersonic jet plasma expansion by reaction of sputtered metal atoms from the needle electrodes with precursor gas of HCl or H2S. Laser induced fluorescence (LIF) techniques, including laser excitation spectrum and dispersed fluorescence, are employed to record the optical spectra. From the rotational analyses of observed spectra, corresponding spectroscopic parameters are experimentally determined. The electronic configurations and chemical bond formations of the three radicals are discussed as well. The main contribution of this thesis including:[1] The LIF excitation spectra of jet-cooled CuCl radical (and its isotopologues) are recorded in the 450-495 nm region, where the spectra have been previously assigned to the b 3 ? 0,1? X1? band system of CuCl. From the detailed rotational analyses in this work, the two band systems are reassigned to B1Π-X1Σand C1Σ-X1Σelectronic transitions. This is concluded from the three conclusive arguments. Further, the radiative lifetimes of the two band systems are determined to be ~4.670 ? sand 4.667 ? s, respectively. The isotopic shifts for all the isotopologues of CuCl are measured, as well.[2] The LIF excitation spectra of NiS in the 450-560 nm region, as well as dispersed fluorescence, have been recorded. In total thirty-five electronic bands are observed in the laser excitation spectra, and twenty-nine of them are experimentally obtained for the first time. From the vibrational analyses, twenty-five bands are suggested to be assigned to four vibrational progressions. Rotational analyses on all observed bands are performed, indicating that all the observed bands should be attributed to the [ ? ? 0] ? X 3 ? 0? transition system of 58NiS (and 60NiS). Corresponding spectroscopic constants are also derived. Furthermore, vibrational energy ladder up to v " ? 6 is obtained from the dispersed fluorescence experiment as well, resulting in accurate determinations of the vibrational frequency and the anharmonicity constant for the ground state of 58NiS.[3] The laser excitation spectra of jet-cooled FeS radicals have been recorded in the 471-485nm region by LIF. By combining our previous work, the harmonic vibrational frequency ( ?e " ? 518 ? 5cm?1) and the anharmonicity constant ( w_e x_e~ "= 1.7 + 0.2cm_-1) of neutral FeS in the X 5? electronic state are accurately derived from dispersed fluorescence spectroscopy. The vibrational frequency ( 518 ? 5cm?1) of FeS in its X 5? state obtained here is in well agreement with the only experimental value which is recently reported from a PES measurement ( ?e " ? 520 ? 30cm?1). Furthermore, the laser excitation spectra of FeS radical in 440-465 nm region are recorded as well. Some spectroscopic parameters of these bands are derived from rotational analyses. However, owing to the severe blending among these bands and the somewhat weak fluorescence intensities in our spectra, it is still challenging for us to make a further and reasonable analysis for these bands at this stage.
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