Photoconduction in KBr and KI Containing<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>F</mml:mi></mml:math>Centers

Abstract

Photoconductivity in potassium bromide and potassium iodide containing $F$ centers has been investigated at 80\ifmmode^\circ\else\textdegree\fi{}K. The product of the quantum yield and unit range has been measured over the spectral range from 2.0 to 5.8 ev with $F$-center concentrations between ${10}^{15}$ and ${10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. Evidence is presented that the mechanism for the production of photoelectrons depends upon the photon energy and the concentration of $F$ centers. Two mechanisms for the production of photoelectrons are suggested by the data: the ionization of $F$ centers by excitons and direct optical ionization of $F$ centers.