Optical properties of the new potential infrared-detectors Cu(I)2SO3 · M(II)SO3 · 2H2O (M = Cu, Fe, Mn, and Cd) series and the influence of M(II) exchange

Abstract

The optical absorption of mixed-valence sulfites such as Cu(I)2SO3 · M(II)SO3 · 2H2O [M = Cu, Fe, Mn, or Cd] were studied and the influence of the M(II) cation on this parameter. A transmission spectroscopy technique was used to measure the optical band gap energies (Eg) in the infrared region and the Eg of Cu(I)2SO3 · Cu(II)SO3 · 2H2O was estimated using a numerical fitting method that can be described empirically by View the MathML source, where χP is Pauling’s electronegativity of metal M. The obtained values were in the interval 0.85–0.95 eV, representing a narrow Eg, which can identify these compounds as potential infrared-detectors.