Effect of Pressure on the Spectra of Five Nickel Complexes

Abstract

The effect of pressure to 150 kbars has been measured on the absorption spectra of five nickel complexes. The results are discussed in terms of the change of 10 Dq and of the Racah parameter B, with pressure. In general 10 Dq, the crystal field strength, increased with pressure, but the increase noted was not the same when calculated for the different peaks of a given complex. This discrepancy may be described in terms of changes of covalency as measured by changes of the Racah parameter B. In general B decreased with increasing pressure showing increased covalency at high pressure. There were some discrepancies in the value of B obtained from different transitions. These may be the result of experimental error, but may also be associated with distortions of the field, or with weaknesses in the assumption of point charges or dipoles.