Development of High Temperature Photoelectron Spectroscopy for a Very Small Amount of Samples

有机化合物的电离能对于电子结构、电离态和分子反应力学的研究是非常重要的。电离能一般可以通过HeI光电子能谱得到。我们的项目是研制适用于极少量样品，加热温度超过300ﾟC的光电子能谱仪。测定了胞嘧啶、硫胞嘧啶、尿嘧啶和硫尿嘧啶等脱氧核糖核酸碱基的光电子能谱，温度在300ﾟ℃左右，样品量小于100 mg。此外，对1，2，4-丁三醇衍生物、螺环[2-、4]化合物(-庚二烯、-庚烯和-庚烷被甲基或环丙基取代)和烷烃(CnH_2n+1；n=6-14)的光电子能谱进行了测量。通过与用MNDO-PM3和AM1方法的半经验分子计算得到的分子轨道能进行比较，对它们的光谱进行了归属。

Ionization energies of organic compounds are very important for studies of electronic structures, ionized states and molecular reaction mechanics. Ionization energies can ordinary be obtained by HeI photoelectron spectra. Our project is development of photoelectron spectrometer that is suitable for a very small amount of samples and heating more than 300ﾟC.As a result, our aim was attained as followings. Photoelectron spectra of DNA bases such as cytosine, thiocytosine, uracil and thiouracil were measured at heating about 300ﾟC and with a smaller amount of sample than 100mg. The keto-enol conformation of these molecules was discussed in relation to assignment of their photoelectron spectra.In addition, measurements of photoelectron spectra were carried out for 1,2,4-butanetriol derivatives, spiro [2、4] compounds (-heptadiene, -heptene, and-heptane substituted with methyl or cyclopropyl) and alkanes (CnH2n+1 ; n=6-14). Their spectra were assigned by comparison with molecular orbital energies obtained with the semi-empirical molecular calculations of MNDO-PM3 and AM1 methods.