LIF Spectra Of CuS And FeS & Transient MIR Spectroscopy Of Macromolecular

This dissertation includes two parts: one is the experimental studies on the laser-induced fluorescence (LIF) excitation spectra of the 3d transition-metal sulfides; the other is the transient infrared spectroscopy on the macromolecular solutions by laser induced temperature jump technique.In the part of LIF excitation spectra, the CuS, and FeS molecules were produced by reaction of sputtered metal atoms with small molecule gas under supersonic jet cooled condition. The laser-induced fluorescence excitation spectra in visible region of them were recorded and analyzed. The main results are summarized as follows:The CuS molecules were produced by the reaction of CS₂ molecules with the copper atoms sputtered from a pair of pure copper pin electrodes under a pulsed DC discharge condition. The jet-cooled laser-induced fluorescence excitation spectra of CuS in the energy range of 17 200 - 19 500 cm^-1 were recorded and investigated. Fourteen vibronic bands were observed and rotationally analyzed, of which eleven bands were reported for the first time. Vibrational and rotational analyses indicated that the fourteen bands can be assigned to the A²âˆ‘^- ( v' = 0 - 4 ) - X²âˆ_3/2 (v" =0, 1) and the A²âˆ‘^- ( v' = 0 - 3 ) - X²âˆ_1/2 ( v" = 0 ) transitions. The molecular constants of these two electronic states were derived, and the isotopic shifts as well as the spin-splitting of the upper state were determined. In addition, the lifetimes of most newly observed bands were measured under the collision-free condition.The FeS molecules were produced by the reaction of H₂S molecules with the cobalt atoms sputtered from a pair of pure cobalt pin electrodes under a pulsed DC discharge condition. The jet-cooled laser-induced fluorescence excitation spectra of FeS in the energy range of 18 800 - 21 600 cm^-1 was recorded and studied for the first time. All of 50 vibronic bands were recorded, of which 48 vibronic bands were rotationally analyzed. Vibrational and rotational analyses indicated that the 46 bands can be assigned to the [19.25] ⁵â–³₄ ( v' = 3 -11 ) - X⁵â–³₄(v" = 0), [19.42]⁵â–³₄( v' = 0 - 7 ) - X⁵â–³₄ (v" = 0), [18.99]⁵â–³₄ (V = 0 - 8, v' =7 overlapped) - X⁵â–³₄ (v" = 0), [19.61] ⁵â–³₄(v' = 0 - 6 ) - X⁵â–³₄(v" = 0) and [19.32]⁵Φ₅ ( v' = 0 - 7 ) - X⁵â–³₄ (v" = 0) ,[19.73] ⁵Φ₅ - X⁵â–³₄ (v'=0-4-v"=0)transitions. In addition, a few weaker bands also indicated as arising fromFe⁵⁴S³² [20.15]⁵â–³₄ (v' = 6-10)-X ⁵â–³₄ (v" = 0). The molecular constants of these all upper electronic excited states were derived. The possible electronic configurations of all upper states have been discussed. Furthermore, the lifetimes of most observed bands were measured under the collision-free condition.In the part of the transient infrared spectroscopy, combining the laser induced temperature jump and the time-resolved MIR laser spectroscopy, the transient time-resolved IR difference spectroscopy of N-isopropylacrylamide (PNIPAM) solution was recorded and analyzed for the first time. The bands in 1570-1700cm^-1 were reassigned. The fast transitional kinetics of typical peaks was investigated and an apparent multistep in the coil-to-globule transitional process was observed. From our data, the transitional process of PNIPAM contains three steps at least in millisecond timescale. According to theoretical models, the three steps were corresponded to the quick formation of small locally collapsed nuclei on the chain; the growth of these nuclei into clusters and the anti-process: the globule-to-coil process respectively. These conclusions were confirmed and explored by further studies which related with the different concentration and different chain length samples.Furthermore, for studying the coil-to-globule transitional process of macromolecular solutions with the Step-Scan time-resolved FTIR spectrometer (IFS66/S), we designed and set up an experimental apparatus combining the laser induced temperature jump with the time-resolved FTIR spectrometer. On this apparatus, we have observed the temperature jump process of the D₂O and the coil-to-globule transitional process of the PNIPAM solution. All results are mainly consistent with the past known.