Journal of Electron Spectroscopy and Related Phenomena 101--103 (1999) 761--764

Reflectivity spectra of rare-earth borides (RB ; R5rare-earth, x54, 6, 12) in the VUV energy range and boron 1s x absorption spectra of YB , YB and LuB were systematically measured in order to investigate the role of the B -cluster in 4 6 12 x the optical spectra and the physical properties. In the optical spectra, the bonding states of B and B -cluster are dominant 6 12 in RB (x54, 6) and RB , respectively. The electronic structures of the B and the B -cluster are discussed.  1999 x 12 6 12 Elsevier Science B.V. All rights reserved.