异丙醇的O-H伸缩振动泛频光谱和分子构像

使用高灵敏的光腔衰荡光谱(CavityRingDownSpectroscopy)技术测出了异丙醇的O-H伸缩v=4、5振动泛频光谱,每个振动能级都有三个吸收峰,被归属为分子构像的O-H伸缩泛频吸收.给出了光腔衰荡光谱的振动泛频吸收的谱带强度公式,并求得分子不同构像在不同振动能级的O-H伸缩泛频吸收的谱带强度;同时利用局域模理论,求得分子各O-H伸缩局域模振子的机械频率(X1)、非谐性(X2)以及解离能(D).用密度泛函(DFT)B3LYP/6-31+G*理论方法优化了分子的各种可能构像,验证了分子存在反式(trans)和偏转(gauche)两种稳定构像,计算的分子的O-H伸缩频率及构像稳定性同实验结果是一致的.

The O-H Stretching Vibrational Overtones and Molecular Conformations of iso-Propanol

The O-H stretching v =4, 5 vibrational overtone spectra of iso-propanol are measured by using highly sensitive cavity ring down spectroscopy (CRDS), where three peaks are observed for each vibrational level. They are assigned to the absorption of the O-H stretching vibrations of molecular conformations. Band intensity formula of overtone for CRDS is given,and band intensities of each band for different levels are obtained. Meanwhile, the mechanical frequencies X1, anharmonicities X2, and dissociation energies D are evaluated by the local mode theory. The different possible conformations of the molecule are optimized by density function theory (DFT) B3LYP/6-31+G* theory methods, where it is confirmed that only the two conformations of trans and gauche forms are stable in this molecule. The calculated O-H stretching frequencies and stability of the molecule are in good agreement with the experimental results.