Wavefuntion in Momentum Space and Molecular Recognition

本研究计划旨在利用电子动量谱（EMS）确定分子在动量空间中的波函数形式。EMS利用非弹性电子散射，伴随着电子碰撞引起的分子电离跃迁。可以确定单个轨道的波函数形式，通过傅里叶变换可以得到真实的（位置）空间的波函数。该方法的难点在于散射截面小，数据积累周期长，信噪比低，难以获得定量数据。为了克服这一困难，我们利用二维探测器构造了一种新的谱仪。该仪器的主要部件在东北大学IMRAM的机械车间制造。2001财政年度的预算主要用于购买建造分光计的材料。因此，我们成功地大大提高了检测效率。通过使用新建造的光谱仪，在2002财政年度，以下课题受到了挑战。通过电子动量分布与碰撞能量的关系表征乙二醛和丁二酮的H0M0和NHOMO. CO.3的高激发态。氢分子离子的高激发态4。N_2O外轨道的动量分布。目前正在对该室进行改造，以配备高温喷嘴，从而使靶向扩展到具有低蒸气压的小分子，如甘氨酸和腺嘌呤。

The present research project aims at determination of wavefunctional forms of molecules in the momentum space by the use of electron momentum spectroscopy(EMS). EMS makes use of inelastic electron scattering accompanied with ionization transition of molecules induced by electron collision. It is possible to determine wavefunctional form of individual orbitals, and through the Fourier transformation wavefunction of real (position) space can be obtained. Further aimed at is to understand the mechanism of molecular recognition in terms of the wavefunctional forms of orbitals such as H0M0.The difficulties of this EMS lies in small scattering cross section, which results in low signal to noise ratio in spite of a long data-accumulation period, and hence it is very difficult to obtain quantitative data. In crder to overcome this difficulty we have constructed a new spectrometer by making use of two-dimensional detector. The major parts of this instrument were manufactured at the machine shop of the IMRAM, Tohoku University. The budget of the fiscal year 2001 was mainly appropriated for the materials to construct the spectrometer. As a result, we have succeeded in improving the detection efficiency significantly.By using the newly built spectrometer, the following topics have been challenged in the fiscal year 2002.1. Characterization of H0M0 and NHOMO of glyoxal and biacetyl through impact energy dependence of electron momentum distribution.2. Higher excited states of CO.3. Higher excited states of Hydrogen molecular ion4. Momentum distribution of outer orbitals of N_2O.At present, the chamber is being modified in order to be equipped with high-temperture nozzle, which makes it possible to extend the target to molecules with low molecules with low vapor pressure, such as glycine and adenine.