Spectral diffusion in the 2E ← 4A2 spin-flip transition of [Cr(NCS)6]3− in glycerol

Abstract

The dependence on the burn fluence, temperature and waiting time of the width of spectral holes in the R₁-line of [Cr(NCS)₆]³⁻ in glycerol is reported. From an extrapolation of the holewidth to zero burn fluence an effective homogeneous linewidth and its temperature dependence is determined. It appears that the direct process to the R₂-level makes a significant contribution to the R₁-holewidth at temperatures >10 K. The time dependence of the spectral holewidth in the range of 10 s–10⁵ s shows a non-logarithmic behaviour which can be described by using a Gaussian distribution for the tunnel parameter λ of the TLSs with λ₀ = 15.9 and σ = 1.99. From a comparison with the [Cr(oxalate)₃]³⁻/glycerol system it is concluded that the nephelauxetic effect has no significant ramifications on spectral diffusion in the title system.