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Digitale Medien

Energy levels of vanadium ions in CdTe (1994)

Peka, P. ; Lehr, M. U. ; Schulz, H. -J. ; [weitere]

Springer

Applied physics 58 (1994), S. 447-451

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ISSN: 1432-0630

Schlagwort(e): 71.55.Gs ; 78.55.Et

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau , Physik

Notizen: Abstract In CdTe doped with vanadium the photoluminescence due to the 3 T 2(F) → 3 A 2(F) transition of V3+(d 2) is detected. Its decay time is determined as (630±20) μs, a result comparable to the analogous emissions in various host lattices. Further emissions around 5000 cm−1 and 9000 cm−1 are caused by charge-transfer transitions or bound-exciton decay. Excitation and sensitization spectra yield information on the positions of the energy levels within the gap, which are discussed using two different models. At T=4.2 K, the distance of the V2+/V3+ donor level is 7300 cm−1 and 5700 cm−1 referred to the valence and the conduction band edges, respectively. The absence of V2+(d 3) centres is tentatively ascribed to the existence of deeply bound excitons.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00332435

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Digitale Medien

Vapour growth, EPR and optical study of Znse:Ti single crystals (1994)

Klimakow, A. ; Dziesiaty, J. ; Korostelin, J. ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Advanced Materials for Optics and Electronics 3 (1994), S. 253-260

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ISSN: 1057-9257

Schlagwort(e): Seeded chemical vapour transport ; Titanium doping ; Electron spin resonance ; Paramagnetic impurities ; Static Jahn-Teller effect ; Dynamic Jahn-Teller effect ; Photoiuminescence ; Excitation spectra ; Photo-ionization of impurities ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik

Notizen: Znse:Ti crystals were grown by seeded chemical vapour transport (SCVT) in a hydrogen atmosphere. In situ doping with titanium was carried out from an additional TiSe source in the quartz ampoule at 1460 K. The Good homogeneity of the Ti distribution and the presence of only a few defects have been demonstrated by etch pit and X-ray topography studies. For the frist time, Ti3+ (3d1) centres in a II-VI semiconductor compund are detected. The concentration of localized centres of Ti2+ and Ti3+ in high-resistivity material determined by EPR is about 5 × 1016 cm-3. Fe3+, Ni2+ and traces of Mn2+ are additionally observed. Below 77K an anisotropic EPR spectrum of Ti3+ (d1) is recorded, indicating both a dynamic and a static Jahn-Teller effect of the 2E(D) ground state. At lower temperatures clear evidence of the static Jahn-Teller effect is observed. The frist emission and excitation spectra of Ti impurities in II-VI compounds are presented. An emission near 3400 cm-1 is assigned to the 3T2(F) → 3A2(F) transition of Ti2+ (d2). Its excitation structures coincide with the known absorption bands to 3T1(P) and 3T1(F). A further structured luminescence band at 4700 cm-1 is related to 2T2 → 2E(D) transition of Ti3+ (d1). Ti ions form a deep donor level Ti2+/Ti3+ situated approximately 14,100 cm-1 above the valence band. This photo-ionization threshold is derived from the excitation measurements in accordance with previous photoconductivity experiments.

Zusätzliches Material: 8 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/amo.860030136

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Effects of 10 days 6 degrees head-down tilt on the responses to fluid loading and lower body negative pressure (1991)

Hillebrecht, A. ; Blomqvist, C. G. ; Kropp, J. ; [weitere]

In: Other Sources

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Publikationsdatum: 2011-08-24

Beschreibung: In an international collaborative project six normal male subjects were studied before, during and after 10 days 6 degrees HDT. Fluid intake was controlled at 40 ml/(kgbw day). Urine volume and body weight were determined daily. Fluid loading and LBNP were performed in all three phases of the study. Body weight diminished by 2.6% because of fluid loss. Blood volume diminished by 13%. The responses to fluid loading were similar in the three phases of the study. Sixty minutes after end of infusion only 5.5% of the infused saline remained in the intravascular compartment. Excess interstitial fluid was eliminated in the next 24 hs but a negative balance was recorded also in the following day. The compliance of the lower limbs expressed as the rate of limb volume change/unit LBNP change was increased at the end of the HDT phase and during the post HDT phase. The set point of intravascular volume was defended, as shown by the response to FL. HDT increased the compliance of the lower limbs.

Schlagwort(e): Aerospace Medicine

Materialart: Acta astronautica (ISSN 0094-5765); Volume 23; 19-24

Format: text

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