Journal of Physical Chemistry A, Vol.122, No.4, 923-928, 2018
The High-Resolution 4f-5d Absorption Spectrum of Divalent Dysprosium (Dy2+) in Strontium Chloride Host SrCl2: Fine Structure and Zero-Phonon Transitions Revealed
The virtual lack of information on electronic spectra of divalent lanthanide elements (Ln(2+)) other than Sm2+, Eu2+, Tm2+, and yb(2+) has prompted us to set for synthesis and characterization of novel Ln(2+) systems. First successful attempt concerned SrCl2/Nd2+ single crystals. Here, we report stabilization of divalent dysprosium in a chloride host. Importantly this has been accomplished with Dy ions introduced in a divalent state during synthesis, unlike by gamma-irradiation of Dy3+ systems employed previously. This synthesis method yields good quality SraCl(2)/Dy2+ single crystals. The electronic absorption spectra of Dy2+ doped in SrCl2 have been recorded with high resolution at liquid helium temperature (4.2 K). Identification of the absorption bands occurring in the spectral range of 5000-45000 cm(-1) is achieved. On the basis of theoretical calculations using semiempirical Hamiltonian model, assignment of bands and determination of the Hamiltonian parameters for Dy2+(4f(9)5d(1)) configuration is carried out. The experimental and theoretical studies reveal fine structure and zero-phonon transitions and thus enable high-resolution assignment of spectral lines. It is shown that spin-forbidden transitions gain relatively high intensity due to significant admixing of low-spin character to nominally high-spin states.