Raman scattering investigation of surface modification in heat-treated BaFCl

Raman Scattering measurements on pristine and heat-treated BaFCl single cry stals are carried out. These measurements are carried out in an orientation where the laser beam is incident parallel to the c-axis and only three mod es are allowed in this orientation. The pristine sample showed three modes as expected, bur after heat treatment, surprisingly, it showed all the six modes. The observation of all the six modes in the heat-treated sample is d iscussed in: the light of the results of X-ray Laue diffraction, Rutherford backscattering and surface roughness measurements. The results strongly su ggest surface modification in heat-treated BaFCl possibly due to surface me lting and resolidification.