Vibronic interaction and crystal structure distortion in Cm4+:CeF4

We have applied selective excitation to unravel the complex 5f state spectra of Cm4+ in CeF4 which arises from multiple metal ion sites and vibronic interactions. An unusual laser-induced site distortion on one of the two ion-sites has been studied. Distinct spectral lines of the distorted ion site were detected. The site distortion was found to be stable below 45 K and reverted, via a thermally activated process, at higher temperatures. Below 45 K, persistent spectral holes were burnt in the absorption lines of Cm4+ on distorted site. Site distortion and hole burning are interpreted based on excited-state vibronic coupling and the assumption of an asymmetric two-minimum potential surface. 15 refs., 2 figs