Optical absorption spectra of MnCl2.2H2O. I

Abstract

The relative intensities and the energies of the electric dipole absorption spectra of MnCl2.2H2O (V-lines in the 27000 cm-1 region) are investigated as functions of temperature with polarised light. Their magnetic field dependence is also studied both in paramagnetic and ordered state. It is confirmed from the angular dependence of Zeeman patterns in the b plane that the principal axes x', y' and z of g-values in the excited states are obtained by rotating the crystallographic axes c, a' and b by pi /4 around b(z). The preferred spin axis in the spin-flop region is also found to coincide with the a (or a') axis. The values of exchange fields in the ground and excited state are determined from the observed exchange splittings and g-values. Experimental results suggest that the observed line spectra are all magnon sidebands.