Study on Fundamental Processes and their Control of Condensation and Evaporation by Laser Excitation

点击翻译按钮获取中文摘要

The aim of the present study is to understand the fundamental process of condensation and evaporation from the standpoint of molecular clustering and the possibility of controlling the process with the thermal excitation method by using lasers. For the purpose, atomic/molecular beams of metal and nonmetal vapors were produced by the laser and electron-beam heating method. Clusters formed in the condensation process of these beams were irradiated by a laser beam to be excited on thermal level before striking a film condensate of which thickness were measured by a film thickness meter. The effects of the laser intensity and irradiation conditions on the features of film condensation also were investigated with a quadruple mass spectrometer and FTIR analyzer. It is found that the condensation rate can be changed by the laser irradiation. These effects of laser irradiation depend on the clustering process; the more clusterized the vapor atoms are, the more remarkable affect would be observed and the finer structure of the condensate could be obtained. The irradiation has little effect for vapors which are hardly clusterized. The laser of smaller wave lengths or higher energies has more intense effect on the condensation process. This can be attributed to the change in the intermolecular potential between molecules or atoms of clusters by laser irradiation rather than the change in their thermal energy. From these result, the possibility to control the fundamental process of condensation by laser irradiation has been evidenced.