Spectroscopy of Nd:KYF4

Growth and spectroscopic analysis of Tm, Ho:KY F4

“…For each class of sites we can distinguish at least five different spectra (figures 4 and 5). Our results agree with those in [7] and [8].…”

“…We emphasize that our measurements have been performed both at 10 and 77 K crystal temperature, whereas the results of [10] refer only to 80 K temperature. The only low temperature spectral analysis available in the literature is the one of [8] on Nd doping and in this case the authors found more than six types of sites.…”

“…Another argument that agrees with this attribution is the larger crystal splitting shown by the first class of spectra. In fact, it was demonstrated in [8] that the splitting is larger for ions in the first class of sites. We emphasize that our measurements have been performed both at 10 and 77 K crystal temperature, whereas the results of [10] refer only to 80 K temperature.…”

“…Some works are also available for the UV and VUV regions [7,19,20]. The papers devoted to IR spectroscopy are not as many as for the preceding cases: [10] on holmium, [21] on erbium and finally [5] and [8] on neodymium. Among all these works, very few of them are really oriented for understanding the structural characteristics of the crystal (see [7,8] and [10]) and, as already said, these are not in agreement in their conclusions.…”

“…To understand the reason for this somewhat unexpected result we decided to carefully investigate the spectroscopic features of Tm-Ho:KYF. In fact, the structure of the crystal is still an open question: KYF has been sometimes considered as a multisite host material [5,6] and sometimes as a disordered one instead [7,8]. Moreover previous authors were not in agreement regarding the number of different sites of the trivalent rare earth: despite the fundamental agreement on the existence of two main 'classes' of sites, the number of their 'subclasses' varies, among the various papers, from three for every class [9][10][11] to two + five [8] and some authors even state [12] that erbium ions occupy only a single class of sites.…”