Excited states of modified oxygen-deficient centers and Si quantum dots in Gd-implanted silica glasses: emission dynamics and lifetime distributions.

The emission centers and excited state characteristics of silica glasses implanted with Gd ions were studied by time-resolved pulsed cathodoluminescence. It was found that in the process of ion implantation, two types of new emission centers associated with Gd ions as well as Si quantum dots are formed in glassy silica. The distributions of excited states over the lifetime were found for both new centers and Si quantum dots.

Energy band gaps and excited states in Si QD/SiO /R O (R = Si, Al, Zr) suboxide superlattices.

X-ray and optical spectroscopies were applied in order to study the band structure and electronic excitations of the SiO /R O (R  =  Si, Al, Zr) suboxide superlattices. The complementary x-ray emission and absorption measurements allow for the band gap values for the SiO layers to be established, which are found to have almost no dependency on the cation type R. It is determined that, after annealing, the stoichiometric factor x remains near 1.

Charge Transport and the Nature of Traps in Oxygen Deficient Tantalum Oxide.

Optical and transport properties of nonstoichiometric tantalum oxide thin films grown by ion beam deposition were investigated in order to understand the dominant charge transport mechanisms and reveal the nature of traps. The TaO films composition was analyzed by X-ray photoelectron spectroscopy and by quantum-chemistry simulation. From the optical absorption and photoluminescence measurements and density functional theory simulations, it was concluded that the 2.

Luminescence of impurity-bound excitons in Li6GdB3O9:Ce3+ single crystals.

The anomalous (τ < 10 ns) luminescence of wide bandgap crystals of lithium-gadolinium orthoborate Li(6)GdB(3)O(9) doped with trivalent cerium ions, has been revealed for the first time and investigated through the low-temperature time-resolved vacuum ultraviolet synchrotron spectroscopy. It was shown that the optical transitions at 6.2 eV are due to electron transfer from the ground 4f(1) states of Ce(3+) ion onto the autoionized states near the conduction band bottom of a crystal.

Resonant inelastic x-ray scattering and UV-VUV luminescence at the Be 1s edge in BeO.

We carried out a combined study of UV-VUV luminescence and resonant x-ray emission from BeO single crystals with incident photon energies in the vicinity of the Be 1s absorption edge. The x-ray emission spectra show that at the Be 1s photoabsorption edge the lattice relaxation processes in the excitation site take place already on the timescale of the radiative decay of the core excitation. Comparison of the x-ray emission and the luminescence spectra indicates that the maximum energy loss of the process of lattice relaxation during the decay of inner-shell holes is similar to the loss that occurs in the self-trapping process of valence excitons.

Luminescence properties of undoped LiBaAlF6 single crystals.

This paper presents the results of the study of electronic excitations in undoped LiBaAlF(6) single crystals by means of luminescence spectroscopy and complimentary optical methods. The intrinsic emission at 4.2 eV due to self-trapped excitons was identified.

A luminescence spectroscopy and theoretical study of 4f-5d transitions of Ce3+ ions in SrAlF5 crystals.

This research is focused on the 4f-5d transitions in Ce(3+) centers doped into tetragonal β-SrAlF(5) single crystals belonging to the I4(1)/a space group. The presence of four non-equivalent Sr(2+) sites in this compound leads to the appearance of three spectroscopically non-equivalent Ce(3+) luminescence centers, which can be well distinguished using a time-resolved laser spectroscopy technique. All 4f-5d transitions have slightly varying excitation and emission energies with characteristic probabilities resulting in several decay times that can be determined experimentally.

Transformation of the excitation energy in aniondefective corundum.

Some regular features of the excitation energy transformation in anion-defective crystals of alpha-Al2O3 were analysed by the sub-nanosecond spectroscopic method. The samples were excited using synchrotron radiation and high-density pulsed electron beams. It was shown that much of the energy of the ionising radiation absorbed by the crystals was liberated as the luminescence of F- and F-centres immediately at the moment of irradiation.