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

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 Eg(χP)=-0.62χP2+1.88χP-0.5, 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.

The optical absorption of mixed-valence sulfites were studied and the influence of the M(II) cation. Band gap energies were determined.