Color centers in KCN: ferro-elastic alignment and free optical absorption of phonons
Description
Some color centers in KCN pure and KCL or KOH doped are studied. The used tecniques for detection of these color centers were optical absorption and electron paramagnetic resonance (EPR). To obtain this color centers crystals were always exposed to X-rays. With an optical absorption technique, one color center was analysed after X-ray irradiation followed by a suitable photochemical process. Throught the EPR technique the F center and three other centers produced by radiation damage were observed through several KCN solid phases. As in the orthorhombic and ferroelastic phase (temperatures between 168K and 83K), the crystals of KCN present one multidomain structure responsable for strong light scattering on the optical absorption spectra and EPR spectra that does not present the resolved lines formed above 168K, one system of aligned domains was obtained through mechanical stress built specifically to be capable of reducing the number of distinct domain, and this allowed us to observe of partially resolved EPR lines. (Auhtor)
Availability note (English)
MF available from INIS under the Report Number.Abstract (Portuguese)
Estudam-se alguns centros de cor nos cristais de KCN puro e KCN dopado com KCL ou KOH em varias proporcoes. As tecnicas usadas para a detecao desses centros foram: absorcao otica e ressonancia paramagnetica eletronica (RPE). A obtencao dos centros foi feita sempre atraves da exposicao dos cristais aos raios X. Com a tecnica de absorcao otica foi analisado um centro de cor criado apos a irradiacao com raios X seguida de fotoquimica conveniente. Atraves da tecnica de RPE o centro F e tres outros centros que sao produto do dano pela radiacao foram observados em diversas fases solidas do KCN. como na fase ortorrombica e ferroelastica (teperaturas entre 168K e 83K) o cristal de KCN apresenta uma estrutura de dominios cristalinos que faz com que os sinais de absorcao otica sejam perturbados por intenso espalhamento de luz e os espectros de RPE nao apresentem a mesma resolucao encontrada acima de 168K, construiu-se um sistema de alinhamento dos dominios por meio de pressao uniaxial capaz de reduzir o numero de dominios distintos, o que permitiu a observacao da resolucao parcial das linhas de RPE. (Autor)Files
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Additional details
Additional titles
- Original title (Portuguese)
- Centros de cor em KCN: alinhamento ferroelastico e absorcao otica livre de fonons
Publishing Information
- Imprint Pagination
- 119 p.
- Report number
- INIS-BR--251
INIS
- Country of Publication
- Brazil
- Country of Input or Organization
- Brazil
- INIS RN
- 16025328
- Subject category
- S75: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;
- Resource subtype / Literary indicator
- Numerical Data, Thesis
- Descriptors DEI
- ABSORPTION SPECTRA; COLOR CENTERS; CRYSTALS; CYANIDES; DOPED MATERIALS; ELECTRON SPIN RESONANCE; EXPERIMENTAL DATA; LOW TEMPERATURE; PHONONS; POTASSIUM COMPOUNDS; PRESSURE DEPENDENCE; VERY LOW TEMPERATURE; X RADIATION
- Descriptors DEC
- ALKALI METAL COMPOUNDS; CRYSTAL DEFECTS; CRYSTAL STRUCTURE; DATA; ELECTROMAGNETIC RADIATION; INFORMATION; IONIZING RADIATIONS; MAGNETIC RESONANCE; MATERIALS; NUMERICAL DATA; POINT DEFECTS; QUASI PARTICLES; RADIATIONS; RESONANCE; SPECTRA; VACANCIES