Role of the 4f55d band in the radiationless 5D1→5D coupling in BaCl2:Sm2+ and BaBr2:Sm2+

Abstract

In this paper, the adiabatic relaxation theory is applied to investigate the origin of rare-earth fluorescence quenching involving multiphonon transitions. The energy level schemes for BaCl,:Sm2+ and BaBr,:Sm H have been obtained from the observed fluorescence spectra. The phonon cutoff frequencies, 210 and 140 cm-1 for BaCl, and BaBr" respectively, have been determined from vibronic sidebands. From the observed temperature dependence of the fluorescence intensities and lifetimes, it is shown that the 5 D, and 5 Do levels are thermally quenched through radiationless excitation to the 4f 5 5 d band and that the population of the 5DO level from 5D, involves the 4f 5 5d band as an intermediary. This indirect f(--;d)--;f relaxation mechanism appears to have resulted from the proximity and relatively large displacement between the adiabatical surfaces of the low-lying 4f 5 5 d and the 5D, states of Sm2+ in BaCl, and BaBr,.

Luminescence properties of Sm2+-activated barium chloroborates

“…It should be noted that a weak line at 683.2 nm and a strong one at 683.9 nm occur in the region corresponding to the 5 D 0 → 7 F 0 transition. Neither of these peaks corresponds to luminescence of Sm 2+ in the excess BaCl 2 phase, as only one line for the 5 D 0 → 7 F 0 transition was observed at 687.1 nm in singlecrystal BaCl 2 [12]. In addition, the same luminescence spectrum was observed in Ba 2 B 5 O 9 Cl with a 10 mol% excess of BaCO 3 .…”

Luminescence and X‐ray phosphor properties of samarium and lanthanum‐doped cubic barium chloride

“…The temperature dependence of the 5d transitions is well known in Sm 2+ spectroscopy to reflect the position of the lowest 4f 5 5d 1 level relative to the 5 D J levels [4], and by fitting the temperature dependence of the strongest broad band, which we assign to the tetragonal site, to a simple two level model involving the lowest 4f 5 5d 1 level and the 5 D 0 level we deduce that the former lies 800 cm -1 above the latter. A more detailed analysis of the Sm spectral characteristics will be given elsewhere.…”

Photoluminescence properties of Sm2+-doped BaBr2 under hydrostatic pressure

“…1a) shows relatively sharp lines at approximately 690, 700, 730, 765, and 825 nm, which originate from 5 D 0 -7 F J (J¼0, 1, 2, 3, 4) transitions of Sm 2 þ . In addition to the narrow line emission, a broadband emission peaking at about 700 nm can be observed; this band can be attributed to 5d-4f transitions [21]. The excitation spectrum (Fig.…”