| Owing to the prominent role and the important significance of van der Waals interaction in physics, chemistry, biology, life science and other related areas, plenty of theoretical and experimental researches toward the van der Waals complexes have been carried out. In this dissertation, rovibrational spectra of several types of gaseous van der Waals complexes are examined by a tunable mid-infrared diode laser spectroscopy coupled with the supersonic expansion technique.1) The internal-rotation/vibration bands of the Ne-D2O complex have been measured in the v2bend region of D2O monomer. The detected rovibrational spectra are assigned as Π(111,v2=1)←∑(O00),∑(111,v2=1)←∑(000) and n=1,∑(000,v2=1)←∑(O00) band of ortho20Ne-D2O. Strong perturbations between the vibrationally excited rotational states are evident by the irregular spectra. The observed spectra are analyzed separately with a three-state J-dependent Coriolis plus J-independent angular-radial coupling model and a three-state Coriolis coupling model. The former model works more successfully than the latter. Precise molecular constants for the ground and excited vibrational states of ortho20Ne-D2O isotopomer as well as the Coriolis and angular-radial coupling constants have been determined. The van der Waals stretch frequency is found to decrease significantly upon the vibrational excitation of the D2O v2bend. Spectra of22Ne-D2O are also observed as well as those of para20Ne-D2O Π(110,v2=1)←∑(101) band, but no rotational analyses are carried out because of the incomplete band result from the mode hop of the laser source.2) Rovibrational spectra of Ar-D2O and Kr-D2O complexes are measured in the v2bend region of D2O monomer. The ortho Π(111,v2=1)←∑(000) and∑(111,v2=1)←∑(000) bands for both complexes are identified and analyzed in terms of a nearly free internal rotor model. Molecular constants for the excited vibrational states and the Coriolis coupling constant are determined accurately, except the constants of Π(111,v2=1) f parity state which are obtained by contour fitting. Although the fitted Coriolis coupling constant suggests strong mixing between the stretching and internal rotor states via angular-radial coupling, the stretching band was not observed under our experimental conditions. A comparison of the observed band-origin shifts of Ar-D2O and Kr-D2O with those of Ne-D2O shows regular trends from Kr-D2O to Ne-D2O.3) The high resolution rovibrational transitions of Rg-H2O (Rg=Ne, Ar, Kr) complexes are observed in the v2bend region of H2O monomer. Although the spectra of Kr-H2O and Ne-H2O are detected for the first time, the rotational analyses are unable to be carried out due to the limited survey spectral range. The detected Kr-H2O transitions are identified as the ortho Π(110,v2=1)←∑(101) band. According to the distribution of observed transitions, preliminary analyses are also carried out for Ne-H2O.4) The open-shell complex O2-N2O is examined in the v1bend region of N2O monomer. Eight subbands of the complex are identified after spectra of N2O dimer and trimer are distinguished. The b-type complex transitions are fitted and constants of excited vibrational state are determined. The small variation of rotational constants before and after the vibrational excitation shows the intermolecular potential energy surfaces are similar in the ground and excited states. The shift between the fitted band-origin of the complex and that of the monomer is much smaller compared with those of analogous close-shell complexes. |
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