The binding energy spectrum and electron momentum distributions for the outer valence orbitals of n-propyl iodide molecule have been measured using the electron momentum spectrometer employing non-coplanar asymmetric geometry at impact energy of 2.5 keV plus binding energy. The ionization bands have been assigned in detail via the high accuracy SACCI general-R method calculation and the experimental momentum profiles are compared with the theoretical ones calculated by Hartree-Fock and B3LYP/aug-cc-pVTZ（C,H）6-311G？？（I）. The spin-orbit coupling effect and intramolecular orbital interaction have been analyzed for the outermost two bands, which are assigned to the iodine 5p lone pairs, using NBO method and non-relativistic as well as relativistic calculations. It is found that both of the interactions will lead to the observed differences in electron momentum distributions. The experimental results agree with the relativistic theoretical momentum profiles, indicating that the spin-orbit coupling effect dominates in n-propyl iodide molecule.
The binding energy spectra and electron momentum distributions for the outer valence molecular orbitals of gaseous 2-fluoroethanol have been measured by the non-coplanar asym- metric （e, 2e） spectrometer at impact energy of 2.5 keV plus binding energy. The quantitative calculations of the ionization energies and the relevant molecular orbitals have been carried out by using the outer-valence Green＇s function method and the density functional theory with B3LYP hybrid functional. The observed ionization bands in binding energy spectra, as well as the previous photoelectron spectrum which was not assigned, have been assigned for the first time through the comparison between experiment and theory. In general, the the- oretical electron momentum distributions calculated by B3LYP method with aug-cc-pVTZ basis set are in line with the experimental ones when taking into account the Boltzmann- weighted thermo-statistical abundances of five conformers of 2-fluoroethanol.
