Development of new techniques for the study of chemical reactions using superfluid He droplets

在本项目中，我们打算开发新的技术，用于研究低温化学反应，使用超流氦液滴。超流氦液滴是氦原子团簇，具有超流性质。它已被证明，一个可以很容易地捕获分子在He液滴，并执行高分辨率的光谱自由旋转的液滴。He液滴的环境对嵌入分子没有明显的扰动，因此嵌入分子的能级和其他性质与自由分子几乎相同。由于液滴的温度为0.4 K，He液滴一定是研究低温下分子化学反应的独特系统。为了将He液滴技术应用于低温化学反应的研究，我们在本项目期间开发了He液滴脉冲喷嘴以及产生强红外脉冲的新激光系统。此外，我们还测量了邻苯二甲酸及其货车德瓦耳斯团簇与Ne、Ar、N_2和H_2的高分辨LIF光谱。我们可以精确地控制酞菁周围的货车范德华团簇的大小。对货车范德瓦尔斯团簇的成功观测表明，氦滴技术不仅可用于化学反应的研究，而且可用于通过调节货车范德瓦尔斯团簇的大小来控制化学反应。

In the present project, we intended to develop new techniques for the study of low temperature chemical reactions using superfluid He droplets. Superfluid He droplets are the clusters of He atoms, that possesses superfluid properties. It has been shown that one can easily trap molecules in He droplets, and perform high-resolution spectroscopy of free rotation in the droplets. The environment of He droplets does not perturb the embedded molecule significantly, so that the energy levels and other properties of the embedded molecule are almost the same as those of free molecules. Since the temperature of the droplets is 0.4 K, He droplets must be a unique system for the study of chemical reactions of molecules at low temperatures. In order to apply the technique of He droplets to the study of low temperature chemical reactions, we have developed a pulsed nozzle of He droplet as well as a new laser system that produces intense IR pulses during the period of this project. In addition, we have measured high-resolution LIF spectra of Phthalocyanine and its van der Waals clusters with Ne,Ar,N_2, and H_2. We could control the size of the van der Waals clusters around Phthalocyanine precisely. The success of the observation of the van der Waals clusters indicates that the technique of He droplets is useful not only for the study of chemical reactions, but also for controling chemical reactions by adjustiong the size of van der Waals clusters.