The electronic structure of methane has been studied in detail by the high Performance energy multichannel electron momentum spectrometer developed recently. The accurate electron momentum distributions of the It2 and 2a1 valence.orbitals of methane are measured. Excellent,agreernent can be found between the experimental data and the calculittions using the HartreeFock method and CI method with the 146-GTO basis functions. In the inner valnce regionclearly satellite structures of the 2a1 orbita1 are observed. The experimental binding energiesand pole strengths are compared with the result, of 2ph-TDA Green function’s calculation. EMSmeasurements and the 2ph-IDA calculation can give The consistent values of binding energies,while the 2ph-TDA calculation is found to overestimate the mam peak intensity of 2a1 orbit,andmderestimate the intensity of satallite structures.
