Electron Momentum Spectroscopy Study on the Inner Orbitals of Methyl iodide

The binding energy spectrum (BES) and electron momentum profiles (EMPs) of the inner orbitals of methyl iodide have been measured using an electron momentum spectrometer at the impact energy of 1200 eV plus binding energy. Two peaks in the BES, arising from the spin-orbit (SO) splitting, are observed and the corresponding EMPs are obtained. Relativistic density functional calculations are performed to elucidate the experimental EMPs of two SO splitting components, showing agreement with each other except for the intensity in low momentum region. The measured high intensity in the low momentum region can be further explained by the distorted wave calculation.