Prompt and delayed secondary excitons in rare gas solids

Abstract

Direct and indirect creation of excitons in rare gas solids has been investigated with reflectivity and luminescence spectroscopy. For the heavy rare gas solids Kr and Xe, new and more reliable exciton parameters have been deduced. With time-resolved luminescence spectroscopy, fast and delayed secondary-exciton creation has been established and separated. Thermalization of photocarriers and their delayed recombination have been analyzed, including a first attempt to investigate the influence of excitation density on the carrier dynamics. The existence of excitonic side bands of ionization limits E i (either band gap or inner-shell ionization limits) in prompt secondary exciton creation has been established. The threshold energies of these side bands are given by E E nE i th ex » + (n is integer, E ex is exciton energy). The side bands are ascribed to the formation of electronic polaron complexes, superimposed to inelastic scattering of photoelectrons.

Multiplication of electronic excitations in nanophosphors Lu2O3:Eu3+ and Lu2O3:Tb3+

“…When applying more advanced theoretical approach: a multiple-parabolic-branch band model, which takes into account scattering processes in different branches of Brillouin zone beyond the above-mentioned single-parabolic-branch model, considerably lower thresholds for creation of secondary electronic excitations can be obtained in wide gap insulators [10]. The resulting theoretical values agree well with the experimental ones for the secondary exciton production in solid Xe [11] and similar processes have been discussed for other rare-gas solids [12]. However, in the case of NCs one has to keep in mind spatial limitations making situation different from bulk crystals.…”

Excitons in rare-gas solids: Exotic or model-like?

“…In particular, the onset of EPC formation at E g +E ex , and the cross-section of this elementary excitation have been predicted by Devreese et al The results discussed are in good agreement with those predictions. This is a strong argument for EPC observation [7,38,40]. In time-resolved FE-luminescence excitation spectra in the vicinity of inner-shell excitations, similar phenomena have been identified.…”

“…In time-resolved FE-luminescence excitation spectra in the vicinity of inner-shell excitations, similar phenomena have been identified. Moreover, EPCs with more than one exciton have been found [40]. In conclusion, RGS FE-luminescence can be used as a probe of such exotic elementary excitations.…”

Decay Kinetics of CeF3 under VUV and X-ray Synchrotron Radiation

“…Time structure of new generation SR sources is excellent for the study of luminescence kinetics: bunches from 100 femtosecond to 100 picosecond duration have a well-defined time separation typically in the range of hundreds of nanoseconds and a small jitter practically unreachable for laser systems, in particular in the short-wavelength range. We should mention a special role of the SUPERLUMI station (DORIS, DESY) in the research of relaxation and energy transfer processes in wide gap solids (including luminescence kinetics studies), e.g., studies intrinsic excitations in rare gas solids [8] and Ce doped scintillators [9]. Recently experimental stations were developed for time-resolved luminescence studies of solids at the P23 beamline of PETRA III storage ring at DESY in Hamburg, FinEstBeAMS and FemtoMAX beamline at MAX IV in Lund.…”