Chris S. K. Mak

Configuration interaction of Pr3+ in PrCl63−

The low-temperature electronic spectra of Pr3+ at an octahedral site of symmetry in the PrCl63− moiety, in crystals of Cs2NaPrCl6, Cs2LiPrCl6, and Cs2NaMCl6:Pr(M=Gd, Y) have been measured and interpreted. Together with the results from d–f emission spectra and resonance electronic Raman spectra, these new data permitted the assignment of symmetry representations of up to 39 out the possible 40 crystal field levels of the 4f2 configuration. The inclusion of configuration interaction with the next highest even parity configuration, 4f6p, into the energy level parametrization reduced the mean deviation of the energy level fit using the single 4f2 configuration model alone, by a factor of 2.9 (i.e., from 32.7 to 11.6 cm−1). In particular, the interaction mechanism for the “anomalous” multiplets 1D2 and 1G4 was shown to arise from crystal field mixing with 4f6p states. This leads to the inclusion of up to about 0.5% of fp-orbital character for these 4f2 eigenvectors. In the 4f2 single-configuration fits to tri...

4f5d–4f2 emission transitions of Pr3+

Abstract The first well-resolved, high-resolution d–f emission spectra are reported for a lanthanide ion. Numerous transitions are observed and assigned for Pr 3+ at a crystal site of octahedral symmetry. The symmetry representation of the lowest f 1 d 1 state is deduced and the eigenvectors from the 4f 1 5d 1 energy level fit are utilized to model the experimentally observed intensities.

Luminescence of the uranyl-ion-doped elpasolite lattice

Distinct species U(III), U(IV), U(V) and U(VI) have been identified when U(VI) or U(IV) species are doped into the cubic elpasolite lattice. The band intensities, and derived vibrational frequencies, in the luminescence and absorption spectra of the uranyl ion situated in this lattice are compared with those of Cs2UO2Cl4. In particular, the intensity enhancement of the B2g→A1g(D4h) hypersensitive transition shows that the uranyl ion occupies a majority site of C2v or lower symmetry.

Synthesis, structure and spectroscopy of rare earth hypophosphites: 3. ytterbium hypophosphite

Abstract Yb(H2PO2)3 crystallizes in space group C2/m. Planar rectangular arrays of Yb3+ ions are doubly bridged by hypophosphite ions in the b direction and singly bridged in the c direction, giving rise to a stacking of corrugated layers in the crystal structure. The YbO6 site symmetry is C2h, but not far from D4h. The vibrational spectra of the hypophosphite anion have been interpreted in detail using unit cell group analysis and are shown to be consistent with the crystallographic data. The 10 K electronic absorption spectrum confirms the presence of two non-equivalent Yb3+ ions situated at centrosymmetric sites in the unit cell. For the first time, the two-centre transitions in the vibronic sidebands have been assigned to the excitation of individual unit cell group modes, showing a one-to-one correspondence with the vibrational spectra. The importance of moiety mode–hypophosphite mode couplings, and of Yb3+–hypophosphite interactions of the type quadrupole–dipole, or higher, is indicated in the interpretation of the intensities of the cooperative vibronic transitions.

Spectroscopic investigation of the Nd3+ 4f25d states in chloroelpasolite crystals

Abstract New spectroscopic results obtained with Nd 3+ -doped Cs 2 NaYCl 6 samples, as well as with the pure Cs 2 NaNdCl 6 crystal, are presented. Static and dynamical properties of the Nd 3+ 4f 3 4 D 3/2 state located in the ultraviolet spectral domain are investigated using time resolved spectroscopy and fluorescence decay time measurements. The Nd 3+ 4f 2 5d bands are studied via ground state absorption as well as by excited state absorption measurements.