Esr of a [111] Defect in X-Rayed LiF

Chu, Yuanchen; Mieher, Robert Lee

doi:10.1103/physrevlett.20.1289

Cited by 28 publications

(9 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…H A (Na + ) centers (an H center localized near a Na + impurity ion) with the orientation along h1 1 0i and the annealing at 110-120 K have been detected in X-irradiated LiF:Na by means of ENDOR method [18]. At the same time, intrinsic H centers (anion interstitial atoms) oriented along h1 1 1i in a regular lattice region and stable up to 60 K have been also detected in LiF using the EPR method [19]. The TSL peak at $65 K corresponding to the annealing of H centers arises in a LiF sample previously irradiated by 62-eV photons (see Fig.…”

Section: Decay Of Ees With the Defect Creation In Lif And Naf Crystalsmentioning

confidence: 82%

Defect creation caused by the decay of cation excitons and hot electron–hole recombination in wide-gap dielectrics

Lushchik

Kirm

et al. 2006

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

Insufficient radiation resistance of construction materials is the Achilles heel for thermonuclear energetics. In wide-gap dielectrics, Frenkel defects are created not only because of the knock-out (impact) mechanism but also because of the decay of the electronic excitations formed during the irradiation (i.e. due to nonimpact mechanisms). The processes of the defect creation at the irradiation of highly pure LiF single crystals at 6-8 K by 1-30-keV electrons, X-rays, or synchrotron radiation of 12-70 eV have been investigated. The annealing processes of these defects in a temperature range up to 200 K have been studied as well. In LiF, creation has been revealed for the following: (1) F-H pairs caused by the decay of anion excitons or by the recombination of electrons and holes, (2) F 0 -H-V K and F-I-V K defect groups at the decay of cation excitons (62 eV), or (3) 20-keV electron irradiation. The mechanism of defect creation at the recombination of hot holes and hot electrons has been discussed for a-SiO 2 crystals with an energy gap between the subbands of a valence band. One of the possible ways to suppress this mechanism (''luminescent defence'') is doping a material by luminescent impurities able to capture a part of the energy of hot carriers before their relaxation and recombination (e.g. in MgO:Cr).

show abstract

Section: Decay Of Ees With the Defect Creation In Lif And Naf Crystalsmentioning

confidence: 82%

Defect creation caused by the decay of cation excitons and hot electron–hole recombination in wide-gap dielectrics

Lushchik

Kirm

et al. 2006

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

show abstract

“…According to the existing experimental data, the interstitial-vacancy processes with the participation of F centres and interstitial fluorine ions or atoms (I and H centres, respectively) dominate at 20-65 K [15,16,19,33,35]. We continued the investigation of this TSL region for We made an attempt to detect TSL at 20-70 K after the irradiation of LiF-1 and LiF-3 by synchrotron radiation of hν exc = 17 eV.…”

Section: Tsl In the Region Of 20-70 Kmentioning

confidence: 99%

“…H centres 2 Revised, 27.09.2005 have been also detected in LiF crystals irradiated at low temperatures. According to EPR and ENDOR data, the annealing of H centres oriented along <111> takes place at about 60 K in the most pure LiF crystals [15]. At the same time, the H A (Na + ) centres (an H centre localized near a Na + impurity ion) with the orientation along <110> have been also detected in LiF [16].…”

Section: Introductionmentioning

confidence: 97%

Low-temperature excitonic, electron–hole and interstitial-vacancy processes in LiF single crystals

Nakonechnyi

Kärner

Lushchik

et al. 2005

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The emission spectra and the excitation spectra of various emissions have been measured in LiF crystals at 9 K using VUV radiation of 10-33 eV. Contrary to the luminescence of selftrapped excitons (3.4 eV), the efficiency of several extrinsic emissions (4.2, 4.6 and 5.8 eV) is very low in the region of an exciton absorption (12.4-14.2 eV). A single exciting photon of 28-33 eV is able to create a primary electron-hole (e-h) pair and a secondary exciton. The tunnel phosphorescence has been detected after the irradiation of LiF by an electron beam or X-rays at 6 K, and several peaks of thermally stimulated luminescence (TSL) at 12-170 K appeared at the heating of the sample. It was confirmed that the TSL at 130-150 K is related to the diffusion of self-trapped holes (V K centres). The TSL peak at ~160 K is ascribed to the thermal ionisation of F′ centres. The TSL at 20-30 K and 50-65 K is caused by the diffusion of interstitial fluorine ions (I centres) or H interstitials, respectively. The TSL peak at ~13 K, the most intense after electron or X-irradiation, cannot be detected after LiF irradiation by VUV radiation, selectively forming excitons or e-h pairs. The creation of a spatially correlated anion exciton and an e-h pair is needed for the appearance of this peak: an exciton decays into an F-H pair, a hole forms a V K and an electron transforms H into I (an F-I-V K group is formed) or an F centre into a two-electron F′ centre (an F′-H-V K group). The analysis of the elementary components of the 9-16 K TSL showed that a phonon-induced radiative tunnel recombination of F′-V K (5.6 eV), F-H (~3 eV) and F-V K (3.4 eV) occurs within these groups.Short Title: Low-temperature excitonic, electron-hole and interstitial-vacancy processes in LiF

show abstract

“…We have produced by low-temperature x-ray and electron irradiation of pure LiF a new paramagnetic defect with (111) symmetry. 13 Results of ESR and ENDOR measurements show that the interstitial defect has the configuration of an F 2~ molecule ion that is situated on a single negative-ion site. The (111) defect model and surrounding lattice are shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The results of our ESR measurements have been presented earlier. 13 In this paper, results of our ENDOR measurements are presented.…”

Section: Introductionmentioning

confidence: 99%

ENDOR Study of a <111> Interstitial Defect in LiF

Chu

Mieher

1969

Phys. Rev.

Self Cite

View full text Add to dashboard Cite

Results of (electron-nuclear double-resonance) measurements and analysis of a (lll)-oriented defect in pure LiF are presented. This paramagnetic defect is produced at low temperatures by x-ray or electron irradiation. The ENDOR hyperfine constants from 11 nonequivalent sets of lattice nuclei have been obtained by fitting the ENDOR spectrum to a spin Hamiltonian. Results of this ENDOR study show that this (111) defect is equivalent to an interstitial fluorine atom that has the form of a negatively charged diatomic molecule ¥o~, centered on a negative-ion site, with its molecular axis oriented along a (111) direction.

show abstract

Esr of a [111] Defect in X-Rayed LiF

Cited by 28 publications

References 14 publications

Defect creation caused by the decay of cation excitons and hot electron–hole recombination in wide-gap dielectrics

Defect creation caused by the decay of cation excitons and hot electron–hole recombination in wide-gap dielectrics

Low-temperature excitonic, electron–hole and interstitial-vacancy processes in LiF single crystals

ENDOR Study of a <111> Interstitial Defect in LiF

Contact Info

Product

Resources

About