A theoretical study of the photoelectron spectra of methanol, ethanol and methanoic acid

• Main Authors: CHEN,KE-TENG, 陳科登
• Other Authors: CHANG,JIA-LIN
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/70937278939113065557

碩士 === 國立臺中教育大學 === 科學教育與應用學系碩士在職專班 === 105 === The purpose of this study was to investigate the photoelectron spectra of methanol (CH3OH), ethanol (C2H5OH) and methanoic acid (HCOOH) by using the density functional theory (B3LYP functional) to calculate the equilibrium geometries and harmonic vibrational frequencies, with the basis set of aug-cc-pVTZ. Franck-Condon factors were computed by using the method developed by our group and the photoelectron spectra of these molecules were simulated. The adiabatic ionization energies were also computed by using the complete basis set (CBS) limit method via CCSD(T)/aug-cc-pVXZ(X = D, T, Q, 5) calculations. The equilibrium structure of ethanol cation was found to belong to the C1 point group, whereas the rest molecular and cationic states of the three molecules are of the Cs point group. The photoelectron spectra of methanol and ethanol have complicated structures due to drastic changes in equilibrium geometries upon ionization. On the contrary, the vibrational structure in the photoelectron spectra of methanoic acid is simple and the simulated spectra are in agreement with experiment. Finally, the computed adiabatic ionization energies of methanol, ethanol and methanoic acid are 10.876, 10.392 and 11.333 eV, respectively, which are in agreement with experiments with relative errors of 0.3%, 0.8% and 0.027%.