R.K. Nesbet, C.J. Noble, et al.
Physical Review A
Recent photoemission studies of noble and transition metals show a predominance of "nondirect" electronic excitations and indicate an anomalous density-of-states peak below the expected d-band. We attribute these observations to second-order (and higher) processes involving secondary phonon- and electron-pair excitations. © 1967 The American Physical Society.