Temperature dependence of the spetroscopic and structural properties of T1GaS2 and T1InS2 crystals

Açıkgöz, Muhammed
The results of photoluminescence (PL) spectra of TlGaS2 single crystal were reported in the 500-1400 nm wavelength and in the 15-115 K temperature range. Three broad PL bands with an asymmetric Gaussian lineshapes were observed to be centered at 568 nm (A-band), 718 nm (B-band) and 1102 nm (C-band). The shift of the emission band peak energy as well as the change of the half-width of the emission band with temperature and excitation laser intensity were also studied. We analyzed the observed results using the configurational coordinate (CC) model. The powder diffraction patterns of TlInS2 and TlGaS2 crystals were obtained and the diffraction data were indexed using CRYSFIRE computer program packet. TlInS2 has hexagonal system with parameters a = 3.83 and c = 14.88 Ao. TlGaS2 has monoclinic system with parameters a = 9.62, b = 4.01 and c = 7.52 Ao with β= 96.30o. Our diffraction studies at low temperatures did not reveal any phase transition for TlInS2 as reported in the literature. The specific heat capacities of both TlInS2 and TlGaS2 crystals calculated from Differential Scanning Calorimetry (DSC) measurements at low temperatures are reported in the thesis.


Escape of photoelectrons and Compton-scattered photons from an HPGe detector
Can, Cüneyt (Wiley, 2003-07-01)
The response function of a planar HPGe detector due to escape of photoelectrons and Compton-scattered photons was studied for a point source with 59.5 keV energy. It was shown that both mechanisms, in addition to Ge x-ray escape, leading to partial deposition of energy, could be observed in the same experiment. A Monte Carlo program was used to investigate these components of the response function. The results indicate that although the escape of scattered photons and Ge x-rays are of the same magnitude, th...
Photoelectron, compton and characteristic x-ray escape from an HPGe detector in the range 8-52 keV
Yilmaz, E; Can, Cüneyt (Wiley, 2004-11-01)
Escape of photoelectrons, Compton-scattered photons and Ge x-rays from an HPGe detector was studied as a function of energy in the range 8-52 keV. A variable-energy source producing Cu, Rb, Mo, Ag, Ba. and Tb x-rays was used. All three mechanisms for energy loss were observed in the same experiment for Ba and Tb, while only x-ray and photoelectron escapes were evident in the spectra for Ag, Mo, Rb, and Cu. Spectral features and possible mechanisms for partial energy deposition were investigated. A Monte Car...
Anharmonic line shift and linewidth of the Raman modes in TlInS2 layered crystals
Yuksek, NS; Hasanlı, Nızamı; Aydinli, A (Wiley, 2004-01-01)
The temperature dependence of the unpolarized Raman spectra from TlInS2 layered crystal was measured between 10 and 300 K. The analysis of the experimental data showed that the temperature dependences of wavenumbers and linewidths are well described by considering the contributions from thermal expansion and lattice anharmonicity. The purely anharmonic contribution (phonon-phonon coupling) was found to be due to three-phonon processes. This work demonstrates that the two Raman modes at 280.9 and 292.3 cm(-1...
Components of detector response function: Monte Carlo simulations and experiment
Pekoz, Rengin; Can, Cüneyt (Wiley, 2006-11-01)
Components of the response function of an HPGe detector for 32 keV incident photons (Ba K alpha x-rays) were studied using a Monte Carlo program. Physical mechanisms and the role of incident photons, detector x-rays, photoelectrons and Compton recoil and Auger electrons for each component were investigated. The position, intensity and shape of the components, particularly of the photoelectrons, were studied in detail. Two distinct components for photoelectron escape were identified by considering the fate o...
An investigation of x-ray escape for an HPGe detector
Can, Cüneyt; Bilgici, SZ (Wiley, 2003-07-01)
X-ray escape peaks for a planar HPGe detector were investigated for a point source of photons with 59.5 keV energy. The effect of the solid angle for the incident photons on the escape probability of Ge K x-rays was studied using collimators with varying apertures. A Monte Carlo program was also developed to estimate the probability of escape for various mechanisms and routes. The experimental and simulation results showed that the escape probability is essentially constant for a wide range of collimator ra...
Citation Formats
M. Açıkgöz, “Temperature dependence of the spetroscopic and structural properties of T1GaS2 and T1InS2 crystals,” M.S. - Master of Science, Middle East Technical University, 2004.