Resonant photoemission from Si(0 0 1)

The evolution of the silicon valence-band photoemission spectra is observed in the photon energy range from the threshold of Si 2p core-level excitation to about 50 eV above this threshold. Besides the Si 3s3p- and 3p-like features in the spectra, there exhibits a new peak which is significantly enhanced while the photon energy is in the neighborhood of 20 eV above the Si 2p core-level excitation threshold. This phenomenon is suggested to be a resonant photoemission caused by the interference between the primary photoexcitation of 3s3p and its autoionization due to direct recombination of the 2p3d excitation.