Radical-recombination Luminescence Research Articles

Synthesis and protective properties of titanium nitride coatings on willemite

The instability of brightness and light output of a photoluminescent phosphor based on Mn2+-activated willemite (Zn2SiO4:Mn) were examined as influenced by the ultrafine titanium nitride layers synthesized based on a molecular layering technique. Using the technique of radical-recombination luminescence excited in a stream of hydrogen atoms, the spectral characteristics of the initial and of modified phosphors were determined.

Features of the ionization mechanism of radical recombination luminescence excitation

A comparison of the temperature-time cycles of radical recombination luminescence (RRL) in atomic hydrogen, based on ZnS and ZnCdS at different partial pressures, is presented. The obtained results allow us to explain the temperature dependences of chemisorption of the charged form of N+ and the optical transition rate upon RRL.

Electrochemiluminescent detection of labile radical intermediates of electrochemical reactions

The article considers the basic principles of electrochemiluminescent spin traps diagnostic method which consists of efficient trapping of intermediate labile radical products (free radicals of complex organic molecules) by electrogenerated radical ions of electrochemiluminescers in different liquid-phase systems including bioobjects. The method permits qualitative and quantitative identification of such particles by measurement of electrolysis radical recombination luminescence (electrogenerated chemiluminescence) intensity which is emitted by electrolyzed solutions of organic electrochemiluminescers. The unique possibilities of the method are illustrated on examples of experimental study of systems with sodium tetraphenylborate and chloride ion.

Radical-recombination luminescence, ion-luminescence and photoluminescence of CaGa 2S 4:Eu

CaGa 2S 4 based luminophors have recently attracted significant attention due to their high efficiency. Very little is known now about the surface and near surface luminescence of these luminophors. The ion-luminescence of CaGa 2S 4:Eu excited by low energy hydrogen ions (up to 3 keV) and the radical-recombination luminescence excited by neutral hydrogen atoms of thermal energies have been studied. The latter is due to chemical energy released at the surface during heterogeneous recombination of atoms into molecules (∼4 eV per recombination event). The radical-recombination luminescence is likely the most surface kind of luminescence, while the ion-luminescence is the luminescence of near-surface layers. In this regard the photoluminescence is the bulk one of with which the characteristics of the surface luminescence might be compared.

Elementary processes involved in the interaction of a solid with a bunch of active gas particles

We propose a new method for investigating processes at the solid-gas interface, which is based on the interaction of the solid surface with a bunch of active species carried by a gas. Using this method, the radical recombination luminescence (RRL) kinetics in crystalline phosphors (CaO-Mn, ZnS-Tm, and ZnS-Cu) excited by a bunch of hydrogen atoms was studied during a time interval of 0.1 s at a temporal resolution of 10 ms. From these RRL measurements, data on the stages of the heterogeneous reaction H+H→H2 were obtained. It was found that the RRL intensity of a ZnS-Cu phosphor decreases with increasing surface electron excitation level. The phenomenon of the total light yield accumulation in ZnS-Cu was observed, which is explained by ionization of the surface electron states.

Radical-Recombination Luminescence of the Uranyl Nitrate Complex in the Adsorbed State

We have investigated the luminescence of uranyl nitrate molecules on the surface of powdery SiO2 upon excitation by UV light (PhL) and hydrogen atoms (radical-recombination luminescence (RRL)). It has been found that the PhL and RRL spectra have a clearly defined vibrational structure. The luminescence peaks of the adsorbed UO2 2− ion are characterized by a systematic longwave shift from the same peaks of crystalline uranyl nitrate (by 230–430 cm−1 at 130 K). Moreover, in the adsorption centers the vibration frequencies of UO2 2− are 20–80 cm smaller than in crystalline salt and the RRL bands are 150–350 cm−1 (130 K) wider than the corresponding PhL bands.

Initial peak on the time dependence of the heterogeneous recombination velocity of hydrogen atoms at the surface of phosphor crystals

The radical recombination luminescence of phosphor crystals in strong atomic fluxes was investigated. An initial emission intensity peak was observed whose amplitude depends on the magnitude of the atomic flux, the phosphor crystal temperature, and the interval between switching the atomic source off and on.

Mechanism and intensity of radical-recombination luminescence of crystal phosphors

This paper constructs a model for radical-recombination luminescence corresponding to experimental data for the excitation of luminescence of a thulium phosphor based on zinc sulfide and calcium oxide by atomic hydrogen. The complicated dynamic behavior of a heterogeneous catalytic reaction is described by assuming that the parameters of the system vary as a function of time or by postulating that one of the stages is autocatalytic. The other method consists of rejecting unjustified assumptions and appealing to purely kinetic factors. The model in this paper incorporates all stages from the standpoint of thermodynamics. The Langmuir-Hinshelwood mechanism is employed and also modified by the assumption that the adsorbed atoms can be in two different states distinguished by different lifetimes relative to the recombination process.

Electron-hole mechanism for the decomposition of zinc sulfide in a hydrogen atmosphere

Chemical analysis is used to study the structural changes on the surface of a ZnS-Cu, Pb phosphor arising in the course of photoluminescence in molecular hydrogen and radical-recombination luminescence excited by hydrogen atoms. The photolysis of zinc sulfide and its decomposition by an atomic-molecular mixture of hydrogen were observed. A mechanism for the reduction involving electrons, holes, and chemisorbed hydrogen is discussed.

Sputtering of zinc sulfide phosphors in excitation of radical-recombination luminescence by atomic hydrogen

Treatment of zinc sulfide phosphors in atomic hydrogen not only produces radical-recombination luminescence (RRL) but also sputtering of the phosphor. The sputtering rate has been estimated for FKP-03k powder phosphor at various temperatures. The atomic hydrogen produces defects of etch-pit type on the surface of a single crystal. The long-term response of the RRL has been recorded for the FKP-03k phosphor and it is ascribed to the sputtering.

Effects of adsorption and desorption on the temperature dependence of radical-recombination luminescence

Effects of adsorption and desorption on the temperature dependence of radical-recombination luminescence

Temperature-time cycles of radical-recombination luminescence in dependence on the partial pressure of the atoms

A comparison is made of the temperature -time cycles of radical-recombination luminescence in atomic hydrogen of phosphors based on ZnS and ZnSCdS with different partial pressures. The results obtained allow us to plot temperature dependences of the concentration of the charged form of chemisorption N+ and the optical transitions during RRL excited by atomic hydrogen.

The decay kinetics of radical-recombination luminescence in crystal phosphors

The features of the decay kinetics of radical-recombination luminescence (RRL) in crystal phosphors excited by atomic hydrogen have been studied. It is shown that the kinetics of the RRL decay can be determined both by the processes in the gas phase (decrease in the hydrogen-atom concentration as a result of their recombination at the walls of the reaction vessel after the atom-generation source has been switched off) and by the processes in the solid itself. Some conclusions are drawn concerning the mechanism of recombination for the RRL of the experimental phosphors.

The mechanism of radical-recombination luminescence in zinc oxide

The temperature-time relationships of the intensity of radical-recombination luminescence (RRL) and the surface electroconductivity of zinc oxide with excitation by atomic hydrogen have been studied. The results are analyzed on the basis of the electron theory of chemisorption and catalysis and the band theory of crystal-phosphor luminescence. The effect of the state of the gas phase and the deep trapping level on the intensity of the RRL is elucidated. A mechanism is proposed for the RRL excitation of this phosphor.

Kinetics of the radical-recombination luminescence of crystal phosphors on excitation by atomic oxygen

The kinetic characteristics of the radical-recombination luminescence of crystal phosphors with a wide forbidden band in atomic oxygen are considered. It is shown that, in order to explain the form of the kinetic curve in the initial stage, simple model representations as to the statistical character of the recombination processes are sufficient. By comparing the theoretical and experimental curves some of the microcharacteristics of recombination between the atoms are determined.

Adsorption and desorption in radical-recombination luminescence

Adsorption and recombination are responsible for the emission in radical-recombination luminescence [1], so it is clear that direct adsorption and desorption measurements must accompany the optical studies in order to elucidate the complex mechanisms involved and to provide quantitative information. However, no such measurements have so far been made for this form of luminescence. Here we report a parallel study of the adsorption and luminescence characteristics for some phosphors.

Effects of IR illumination on the radical-recombination luminescence of crystal phosphors

The effects of infrared light have been examined for the radical-recombination luminescence characteristics of narrow-band and wide-band phosphors; it is found that the stored light sum is small near the surface space-charge region.

Kinetics of radical-recombination luminescence of crystal phosphors under excitation by atomic nitrogen

Kinetics of radical-recombination luminescence of crystal phosphors under excitation by atomic nitrogen

Question of the temperature dependence of the stationary intensity of radical-recombination luminescence

Question of the temperature dependence of the stationary intensity of radical-recombination luminescence

168. Spectral-kinetic characteristics of radical-recombination luminescence in crystal-phosphors activated by manganese: Yu M Naslednikov et al,Izv VUZ Fiz, No 11, 1971, 16–21 ( in Russian)

168. Spectral-kinetic characteristics of radical-recombination luminescence in crystal-phosphors activated by manganese: Yu M Naslednikov et al,Izv VUZ Fiz, No 11, 1971, 16–21 ( in Russian)