Trial production of molecular beam Fourier transform microwave spectrometer designed for solid organic molecule.

本项目的目的是试制一种灵敏的分子束傅里叶变换微波光谱仪，用于测量高沸点的有机固体或液体。我们改进了现有光谱仪的喷嘴设计，使其更容易产生固体和Ar的混合分子束。作为第一步，我们改变了分子束的方向，使其与微波传播方向平行。这是继格拉博(德国基尔大学)和洛瓦斯(美国NIST)之后的进步。由于反射镜的背面朝向真空室的外部，固体样品的处理变得容易，为此我们购买了微波放大器和镜像抑制混频器，以提高入射微波功率和降低微波电路的噪声，作为第二步，我们在获得前一次资助的两年内建造了一个具有两个凹镜(直径550 mm)的法布里-珀罗腔。我们构建了低成本的镜面抛光工具。我们这个项目的目的是确定生物分子与水之间的络合物的分子结构。我们尝试测量了苯甲酸~水、邻苯二酚~水、苯甲酚~水这些络合物的光谱，但没有观察到谱线。用从头算方法对苯甲酸-水配合物的结构进行了估算。

The purpose of this project is a trial production of a sensitive molecular beam Fourier transform microwave spectrometer designed to measure of organic solid or liquid with high boiling point. We improved the nozzle design of our existing spectrometer to make it easier to produce a mixed molecular beam of solid with argon.As the first step we changed the direction of molecular beam to be parallel to that of microwave propagation. This improvement is after Grabow (Kiel U., Germany) and Lovas (NIST, USA). As the back of the mirror faces to the outer of the vacuum chamber, the handling of solid sample become easy.We purchased by this grant the microwave amplifier and the image rejection mixer to improve the sensitivity by increasing of inlet microwave power and reducing the noise of the microwave circuit.As the second step we are constructing a Fabry-Perot cavity having two concave mirrors (550mm diameter) for two years when we got the previous grant. We constructed the tool for polishing the mirrors with low price.Our purpose of this project is to determine a molecular structure of the complex between biomolecule and water. We tried to the measure spectra of these complex ; benzoic acid〜water, catechol〜water, anisol〜water, however we can not observe the spectral lines. We estimated the structure of benzoic acid〜water complex by ab initio calculation.