Nature of Optical Transitions in Copper and Cu:Ni Alloys

Abstract

The direct ${L}_{{2}^{\ensuremath{'}}}\ensuremath{\rightarrow}{L}_{1}$ transition is very apparent in photoemission data from pure Cu; however, as might be expected, there is no evidence for this transition in 87% Cu-13% Ni alloys. In contrast, structure in ${\ensuremath{\epsilon}}_{2}$ for $h\ensuremath{\nu}>~2.1$ eV for the alloy and pure Cu is qualitatively similar. These observations support the assignment of major structure in ${\ensuremath{\epsilon}}_{2}$ of pure Cu to nondirect transitions from the $d$ states and argue against the 5.0 eV peak being due principally to the ${L}_{{2}^{\ensuremath{'}}}\ensuremath{\rightarrow}{L}_{1}$ transition.