title: Hyperfine structure of Ho3+ levels and electron-phonon coupling in YPO4 single crystals.
abstract: High resolution spectroscopy (the finest being 0.01 cm(-1)) was applied in the 75-25,000 cm(-1) and 9-300 K ranges to a 1 mol% holmium doped Y PO(4) single crystal with two purposes: (1) to study the hyperfine splitting of Ho(3+) energy levels of interest for possible quantum manipulation media and (2) to analyze the electron-phonon interaction. The hyperfine structure was clearly revealed for a high number of lines in a wide wavenumber range (up to ~21,500 cm(-1)) and for a large number of multiplets. Several hyperfine patterns were monitored, differing in the number of components (a maximum of 16 could be easily distinguished in a single beautiful pattern), in their separation, and in their relative statistical weight. These features were all understood in terms of a crystal-field model, whose results are in good agreement with experiments and account for the involved level symmetry, the type of transitions (electric and magnetic dipole allowed), and the contribution of a second-order (pseudoquadrupolar) hyperfine coupling between close levels. The electron-phonon interaction, investigated through the thermally induced line shift, was critically discussed in the framework of single phonon coupling and of two phonon Raman scattering models.
authors.affiliation: Physics Department, University of Parma, Parma, Italy. margherita.mazzera@fis.unipr.it
authors.forename: M
authors.initials: M
authors.lastname: Mazzera
authors.forename: R
authors.initials: R
authors.lastname: Capelletti
authors.forename: A
authors.initials: A
authors.lastname: Baraldi
authors.forename: E
authors.initials: E
authors.lastname: Buffagni
authors.forename: N
authors.initials: N
authors.lastname: Magnani
authors.forename: M
authors.initials: M
authors.lastname: Bettinelli