Open AccessEnergy relaxation from STE to In+ centers in NaI:In+ crystals
Author(s) -
Shinta Watanabe,
T. Kawai,
K. Mizoguchi
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1220/1/012031
Subject(s) - luminescence , exciton , excitation , relaxation (psychology) , atomic physics , intensity (physics) , absorption (acoustics) , impurity , materials science , molecular physics , chemistry , condensed matter physics , optics , physics , optoelectronics , psychology , social psychology , quantum mechanics , organic chemistry , composite material
The energy relaxation from host crystals to impurity centers has been investigated by measuring the absorption and excitation spectra and the temperature dependence of the luminescence spectrum of NaI:In + . In the absorption spectrum, the A, B, and C bands due to the In+ centers are confirmed at 3.8, 4.0, and 4.5 eV, respectively. The excitation spectrum for the A T luminescence due to the In + centers responds to the energy position of the A, B, and C bands and also the energy region above the exciton transition of NaI. The fact suggests the existence of the energy relaxation from host crystals to the In + centers. The total intensity of the A T and A X luminescence due to the In + centers exhibits different temperature dependence between the excitations at the C band and host crystals. Under excitation at the C band, the total intensity of the A T and A X luminescence monotonously declines with increasing temperature from 10 to 300 K. On the other hand, under excitation at host crystals, the total intensity of the A T and A X luminescence exhibits an increase with increasing temperature from 10 to 50 K, and a decrease with increasing temperature from 50 to 100 K. We discuss the temperature dependence of the total intensity of the luminescence under excitation at host crystals in relation to free excitons and self-trapped excitons.