Open AccessПрирода аномальной красной люминесценции в нелинейно-оптических кристаллах K-=SUB=-2-=/SUB=-Al-=SUB=-2-=/SUB=-B-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- : Fe
Author(s) -
И. Н. Огородников,
В. А. Пустоваров
Publication year - 2019
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2019.05.47584.14f
Subject(s) - luminescence , exciton , excited state , atomic physics , absorption edge , spectroscopy , absorption spectroscopy , impurity , excitation , ion , synchrotron radiation , absorption (acoustics) , materials science , analytical chemistry (journal) , full width at half maximum , chemistry , band gap , optics , physics , optoelectronics , condensed matter physics , organic chemistry , quantum mechanics , chromatography , composite material
In this work, the spectra of anomalously intense luminescence at 1.675 eV (FWHM= 0.173 eV) in wide-gap (180–3600 nm) nonlinear-optical crystals K2Al2B2O7 were observed experimentally for the first time upon excitation in the spectral region of 4–5 harmonics of the fundamental frequency of the Nd3+ radiation. Using low-temperature (7–293 K) luminescence-optical spectroscopy with selective excitation by synchrotron radiation, it was shown that red luminescence occurs at intracenter 4T1(4G)→ 6A1(6S) transitions in impurity Fe3+ ions with a concentration less than 2 ppm. The high excitation efficiency in the exciton region is due to the partial overlapping of the fundamental absorption edge of the crystal, where mobile excitons are excited, and the broad absorption band with O– Fe charge transfer with a maximum at 6.5 eV. The spectrum and temperature dependence of the luminescence are due to the superposition of two types of luminescence centers (activation energies 9 and 20 meV) based on Fe3+ impurity ions located in regular Al3+ positions of two nonequivalent Al2O7 clusters.