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

已知在超流液氦中未固定的杂质原子存在于液体中形成的气泡状空腔中，而碱金属原子由于Rb*中受激发的价电子的作用，常常在气泡中形成异构体，如Rb*Hen。相反，人们一直认为碱土原子很难形成这样的异构体，因为在该状态中还存在另一个价电子。然而，在我们之前的实验中，我们发现液氦中Mg原子的激光诱导荧光（LIF）光谱提示了Mg^Hen形成的可能性。在本研究中，为了进一步证明这种可能性，我们测量了Mg的LW谱与液氦压力的关系。将实验光谱与理论计算结果进行比较，我们发现这一现象强烈地暗示了Mg^Hen异构体的形成。为了得到上述Mg^*Hen激络合物形成的更明确的证据，我们测量了在5 - 10K的低温He气体中分布的Mg的LW光谱，在这种温度下，He原子在Mg原子周围形成任何气泡状结构。除了我们之前对冷态气体的测量外，我们还测量了冷态气体中Mg的LW光谱。不幸的是，通过激光烧蚀处理模气中Mg原子的激光遇到了一些麻烦，使我们获得的光谱不如模气清晰，因为Mg原子的数量不足。然而，通过这次观测，我们也成功地获得了异构体特有的LIF光谱。这一结果进一步验证了在液氦中形成Mg*Hen异构体的可能性。

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.