While the major peak at 188.2 eV was assigned to the B-B 42 bonds in the icosahedra structure, the peak centered at 188.8 eV was assigned to B-C bonds, and the minor peak at 190.6 eV was assigned to B-O bonds. The B rich B4C or B13C2 phases that form B icosahedra clusters connected by C-B-C linear chains, giving a higher intensity signal for B-B bonds compared to B-C bonds, is typical for B-rich carbide material.