X-ray Absorption Near Edge Structure of Selenium Free Clusters

Selenium clusters have been produced in the free space and their X-ray Absorption Near Edge Structure (XANES) have been measured in situ on the Se K-edge in the Total-Ion-Yield (TIY) mode by utilizing the beam line BL-12C of Photon Factory in KEK. From the observed TIY intensities, the XANES spectrum of Se dimer and that of larger clusters such as a pentamer have been deduced. The first peak in the XANES spectrum of the Se dimer is smaller and broader than that of the larger clusters, suggesting that the first peak of the dimer is a superposition of the 1s-π* and 1s-σ* bound-state resonances.