MN2+ AND FE3+ IMPURITIES IN ARDENNITE BY SPECTROSCOPIC INVESTIGATIONS

The optical absorption and EPR spectra of ardennite originated from Sa lm, Belgium are reported. The optical absorption spectra show five ban ds at 17060, 20780, 22720, 24325 and 26170 cm(-1) that are, assigned f or Mn2+ in distorted octahedral site and the sharp band at 13440 cm(-1 ) is attributed to (6)A(1) --> T-4(1)(G) transition of Fe3+ ion in low concentration. The crystal field parameters which give the best fit f or the observed band positions, B = 675, C = 2860 and D-q = 675 cm(-1) are determined. The broad lines in the EPR spectrum consisting of six almost equally spaced lines with a separation of 72.5 G and g = 2.002 (2) are responsible for Mn2+, whereas g = 4.4014 attributes the Fe3+ i mpurity in a strong tetragonal distortion.