An investigation of distorted wave effects in π^* like molecular orbital by electron momentum spectroscopy

Sensitive images of orbital electron density for the ethane (C ₂H₆) were investigated by using a newly developed electron momentum spectrometer with a wide range of experimental impact energies. Some 'turn up' effects in the momentum distributions of the 1E_g and 3A_1g orbitals were observed at low and high momentum regions compared with plane wave impulse approximation calculations. Moreover, such discrepancies become smaller with the increase in the impact electron energy. The distorted wave effects could be a reasonable explanation for these observed discrepancies. While appropriate theoretical calculations using distorted wave in molecules could not be achieved at present.