Investigations on Quantum Mechanical Properties of Liquid and Solid Helium through Spectroscopic Studies of Impurity Atoms and Molecules

点击翻译按钮获取中文摘要

It is known that an impurity atom Unpinned in superfluid liquid helium resides in a bubble-like cavity formed in the liquid, and that an alkali metal atom often forms an exciplex, such as Rb*Hen, in the bubble due to the effect of the excited valence electron in Rb*. On the contrary, it has been believed that it is difficult for an alkali earth atom to form such an exciplex because of the presence of another valence electron left in the state. However, in our previous experiment, we found that laser induced fluorescence (LIF) spectra of Mg atoms in liquid helium suggest the possibility for the formation of Mg^Hen. In the present research, to obtain a further proof for this possibility we have measured the dependence of LW spectra of Mg upon the pressure of liquid helium. Comparing the experimental spectra with the result of our theoretical calculation we have found that the spell a strongly suggest the formation of Mg^Hen exciplexes.To obtain a more definite proof for the Mg^*Hen exciplex formation mentioned above, we have measured LW spectra of Mg distributed in cold He gas at a temperature of 5 - 10K in which the gas pressure is too low for the He atoms to form any bubble-like structure around the Mg atoms. We have measured LW spectra of Mg in cold tie gas, in addition to our previous measurement for cold tie gas. Unfortunately, some trouble with the laser used for mattering Mg atoms in the die gas through laser ablation has made us to obtain the spectra less clear than for die gas, because of an insufficient number of Mg atoms. Nevertheless, also hi this observation we have successfully obtained LIF spectra peculiar to exciplex. This result has further verified the possibility for the formation of Mg*Hen exciplexes in liquid helium.