凝縮相近傍でのクラスタ過程の分光学的研究

抄録

The infrared absorption spectra of N₂O and CO₂ molecular clusters formed in a supersonic free jet expansion were measured at various source gas pressures and solvent densities. The infrared absorption spectra of N₂O and CO₂ were measured at different positions in the vicinity of the condensate and compared with the monomer and cluster spectra. These spectra are compared with the vibrational spectra of clustering molecules calculated using the molecular dynamics method. The results show that the measured spectra have a distinct difference between the large-size (L) and the small-size (S) clusters. In the case of N₂O, L clusters were observed in a wide range of spatial position, but S clusters were formed in a limited region from the condensate. In the case of CO₂, L clusters were replaced by S clusters at higher pressures. The distance from the condensate at which the S clusters were observed depended on the pressure, and the clustering region of the L clusters was proportional to approximately the cubic power of the mean free path.