Abstract
X-ray K absorption studies of cobalt in the pure metal and in the compounds TbCo5, DyCo5, HoCo5 and ErCo5 have been carried out using a 40 cm Cauchois type bent crystal spectrograph. The K-absorption edge of cobalt in these compounds lies on the lower energy side with respect to its position in pure cobalt. The chemical shifts have been found to depend upon the number of covalent electrons participating in bonding.