Characterization of the double sulfites Cu2SO3 center dot MSO3 center dot 2H(2)O (M = Cu, Fe, Mn or Cd) by photothermal techniques

Structural, thermal and optical properties as well as the non-radiative rel axation time and the characteristic diffusion time tau (beta) of the synthe sized double sulfites Cu2SO3. MSO3. 2H(2)O (M = Cu, Fe, Mn or Cd) were inve stigated by photoacoustic spectroscopy. The positions of the bands for each compound were identified upon gaussian deconvolution and by Kramers-Kronig analysis, and the d-d and intervalence transitions were observed. The dete ction of two absorbing bands with low and high intensities is in agreement with previous results on reflectance for Cu2SO3CuSO3. 2H(2)O. A slight shif t is observed in the peak positions and in the measured thermal diffusivity , capacity and conductivity for different Ms and the thermal conductivity d ecreases with the ionic radius of the M(II) cations.