The model of Vka hole center and ligand hyperpirine interaction in CaF2:Na single cristal тема автореферата и диссертации по астрономии, 01.03.04 ВАК РФ

Tbilisi St-ite University

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GAVASHELI TSISANA ARCHILOVNA

THE MODEL OP Yka HOLE CENTER AND LICAND HYPEHFINE INTERACTIONS IN CaPglNa SINGLE CRISTA1

speoiality 01 02 03 - radiophyaios ■ ABSTRACT

of thfe diesertation submitted for a degree of a candidate of phyeioal and mathematical eoienoes

Tbilisi 995

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The work is oarried out at the Tbilisi State University Soientifio Advisers:

ABBOoiate Member of Acadamy of Soienoos of (¡cur^ia, Pl-ofeBBor T. I. Sanadze

Candidate of Phys.-liath. Soienoes, Assistent Professor R. I. Mirianachvili

Ofiioial Opponents:

Dr. of Phys.-Math. Soienoes, ProfeBBor U.A.Tsintsadze, Dr. of Phye.~Math. Soienoea, Professor T.SH.Abesadze

The defenoe of dissertation will take place at on _ M _•• 1995 at _ o' clock at the

meeting of the Soientifio Attestation Council FM 01. 02. N 1-6 at Tbilisi I. Gjavakhiehvili State University at the adreaee^: TSU, 3, Chavohavadze avenue, Physios Department

The dissertation can be found at Tbilisi State University Pundamenial Library

Copies of the abstract were distributed on

_ "_" 1995

Soientifio Secretary or the ■Soieritifio Attentational Council,

Dp. of Phys.-Math. Soienoea ^/¿it-^JLJ-l'-Kerer.el idze

GENERAL CHARACTERISTICS OF THE. WORK Ant.iinU.i t.y of the theme. The modem technical development ;; t imn Ifîtes the invesUg.it ion of colour centers while the crystals, wiiioh contain different types of colour centers arc used in optical quantum generators, memory oirouits of computer», spt cteal converters and others.

A gr"at bulk of works, considering the oolour cRiilerK, rvfur to electronic point centers, while hole center« art; investigated relatively poor. Besides, hole centers are investigated predicaly only in single orystals with a simple lattice structuré (alkali haMde crystals). The hole centers in fluorit.e type single oryutalu were investigated mainly by EPR and optical methods, whioh do not permit determination of microscopic Btruoture of enters. In fluorite type single orystals the model of hole center is determined .only for V^ center (by maanc of elecLron-nuolear double resonanse method). That'B why the investigation of rire complicated V^ oenter in this orystals is very interesting and actual problem.

The purpose of the dissertation is the determination of tht; model of the V^ hole center and the investigation of hyperfine interaction in CaF,, :Na ingle crystal.

The methods of investigation. Electron paramagnetio resonansb; pulsed methods of discrete saturation and radio-frequency dicorete saturation were used in thiB dissertation.

Scientific novelty. In the di jertatior the hole Vj^ center in CaFgiNa single orystal is investigated in detail for the fi'"st time and the new physical results ara formulated uelow ir. the oropositions, carried on defenoe, are received.

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The fundamental propoBiBhionn, carried on defence:

1 .For the first, tine the reliable microscopic sti-uoture of T^ hole center in Ca?2:Na single orystal was determinated.

; - 2.For the first time the orthorhombioity of the WR Bpeotrun of the V^ oenter was observed and measured the Spin Bamiltonian paramitera, whioh disoribe this speotrum.

3.For the first time the reason of inequivalent EPR epeotium of Vj^ oenter in CaFg.Na single orystal, obtained by 7 irradiation at liquid nitrogen temperature, ie explaned. This inequivalenoy dieeppeared affter heating ox' t£©-eample above 170K.

4.Bxp6rimentaly is shown, that the oonoentration,! of V^ centers in 0af2:№ single orystals, irradiated by

Bouroa >f 170K 1b about one order of magnitude larger' then in single crystals, 1. .-adiated at 77K.

5-A simple devise was construoted, which allows irradiation of sample in Bouroe at constant

tenrperatu *e in the 77-»300 K renge.

6.The Jo« eyTaaetry quadrupole interaction and hyperfine interaction of sodium nuolei with Vj^ oenter was investigated by radio frequency discrete saturation (PPDS) cthod. Tho*angu1ar dependence of RFDS spectra measured and oomponunts of superhyperfine (SH*I) and quadrupole inter*otion tensors were determined.

" 7.THe hyperfine interaction of the VKA oente^ with all the nearest nuolei ie Investigated by the -HITS method and the oompohentB of SHPI tensor« are determined.

Approbation' oi the work and publications. The dissertation materials were reported and discussed on the town Beminars in Uagnatio resonance, and alBO were reported on the symposium "Uagnatio Resonanoe-91" (Kazan, 1991) and ontheAKPERB congress (Kazan, 1994).

The main results of the dissertation are published in th<9 following works:

i .гдвмвш ц.а. , шпионам PJL, гашвш о.в..

сляцрк ЯП» щрсюжо qmpi в Camilla - ИТ, т.34, Н2, с.672-673, (1990).

2.ГАВЖИ Ц.1., ИВШШЙВП1 P.M., дширвдэк д.л.,

САНДДЗК Т.Ж., ' кшулсявж snp спектроскопия дарочрых центров а Са?2:Ва - В кн.; ИвтнтщЯ рвэонанс-91." Натеряаш саноацш, псвцпвпп) 80-хвтюо : С.А.Ажьттльра, 6-8 сентябрь, Казань, с .23-23, (1991). •

3.ГАВАКЖ Ц.А., Д&РАСХЖЯ Д.М.. МВРМНЛШВХЛХ Р.И.,.: ПДГОЦрЖ T.I. , Сверхтонкое ж жшифутшлоз вяомсдайсташ ■она На с дарочшм центром в Са?2:Ка, #ТТ, т.36, 6, с. 1787-1739, (1994).

4.ШШЯ Ц.А. , ДАРАСКЖЯ Д.У., ДЖШПДОК д.л., ; ШШШВВШ Р.1., смидав Т.«., Лкгвдвое сверхтонкое ' взСшкдеОстввв с лфовдм центром в Са?2:Ка - OTT (в . шчаи).