Spin-resolved X-ray photoelectron spectroscopy (SRXPS) and high resolu
tion X-ray photoelectron spectroscopy (HRXPS) studies of the Valence b
ands of ferromagnetic Fe, Co, Co66Fe4Ni1B14Si15 and Ni are reported. T
he SRXPS and HRXPS spectra are compared with theoretical densities of
states (DOS) that are corrected for photoelectric cross section variat
ions within the valence band. Agreement between theory and experiment
is very good for ferromagnetic Fe and Co66Fe4Ni1B14Si15. For Co metal,
experiment agrees poorly with theory incorporating a 1.5 eV exchange
splitting. Agreement is improved if a reduced Co exchange splitting of
1.2 eV is adopted theoretically. The reduced exchange splitting is at
tributed to valence electron correlation in Co metal. Ferromagnetic Ni
shows poor agreement between experiment and theory. The SRXPS Ni spec
tra demonstrate that most of the disagreement concerns the up arrow-sp
in channel.