1B-O1-1425 PDF
イオンのクーロン結晶が拓く低温イオン化学
Recent technical developments of cooling and manipulating atoms and molecules enable us to study various atomic, molecular, and optical processes with an ultimate sensitivity at very low temperatures. Such experimental studies should contribute to astrochemistry, in which accurate reaction rates of various reaction processes at low temperatures are needed. In particular ion-polar molecule reactions are known to be important in production processes of interstellar molecules, since the reactions are very fast at low temperatures. However, there were no extensive measurements of the reaction rates owing to experimental difficulties. In fact most of polar gases easily condensate at higher temperatures than 100 K, and the reaction-rate measurements have been hardly performed at low temperatures. So recently we have constructed a new experimental setup to study cold ion-polar molecule reactions in gas phase. In short the setup consists of a Stark-velocity filter for producing slow polar molecules and an ion trap apparatus for generating cold ion targets, which are sympathetically cooled by laser-cooled Ca+ ions. Using the setup we have measured reaction-rate constants of some ion-dipole systems at a translational temperature lower than 10 K. We will discuss the rotational temperature dependence of reaction-rate constants at low temperatures for some ion-dipole systems.