Temperature shift of the absorption edge and Urbach tail ofZrSxSe2−xsingle crystals

2017 ◽  
Vol 95 (24) ◽  
Author(s):  
Mohamed Moustafa ◽  
Anke Wasnick ◽  
Christoph Janowitz ◽  
Recardo Manzke
Keyword(s):  
Absorption Edge ◽  
Temperature Shift ◽  
Urbach Tail

Temperature shift of the absorption edge in mixed single crystals ofZnxCd1−xSe

1987 ◽  
Vol 36 (2) ◽  
pp. 1174-1177 ◽  
Author(s):  
L. Samuel ◽  
Y. Brada ◽  
A. Burger ◽  
M. Roth
Keyword(s):  
Single Crystals ◽  
Absorption Edge ◽  
Temperature Shift

The Electronic Absorption Edge of Petroleum

1992 ◽  
Vol 46 (9) ◽  
pp. 1405-1411 ◽  
Author(s):  
Oliver C. Mullins ◽  
Sudipa Mitra-Kirtley ◽  
Yifu Zhu
Keyword(s):  
Electronic Absorption ◽  
Absorption Edge ◽  
Spectral Region ◽  
Population Distribution ◽  
Fluorescence Emission ◽  
Crude Oils ◽  
Excitation Wavelength ◽  
Urbach Tail ◽  
Wide Range ◽  
Peak Widths

The electronic absorption spectra of more than 20 crude oils and asphaltenes are examined. The spectral location of the electronic absorption edge varies over a wide range, from the near-infrared for heavy oils and asphaltenes to the near-UV for gas condensates. The functional form of the electronic absorption edge for all crude oils (measured) is characteristic of the “Urbach tail,” a phenomenology which describes electronic absorption edges in wide-ranging materials. The crude oils all show similar Urbach widths, which are significantly larger than those generally found for various materials but are similar to those previously reported for asphaltenes. Monotonically increasing absorption at higher photon energy continues for all crude oils until the spectral region is reached where single-ring aromatics dominate absorption. However, the rate of increasing absorption at higher energies moderates, thereby deviating from the Urbach behavior. Fluorescence emission spectra exhibit small red shifts from the excitation wavelength and small fluorescence peak widths in the Urbach regions of different crude oils, but show large red shifts and large peak widths in spectral regions which deviate from the Urbach behavior. This observation implies that the Urbach spectral region is dominated by lowest-energy electronic absorption of corresponding chromophores. Thus, the Urbach tail gives a direct measure of the population distribution of chromophores in crude oils. Implied population distributions are consistent with thermally activated growth of large chromophores from small ones.

Temperature dependence of slope of exponential absorption edge and the temperature shift of absorption edge in Ge20SbxS80−x glasses

1981 ◽  
Vol 37 (8) ◽  
pp. 667-670 ◽  
Author(s):  
H. Tichá ◽  
M. Frumar ◽  
J. Klikorka ◽  
L. Tichý ◽  
A. Tříska ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Absorption Edge ◽  
Temperature Shift

Absorption edge, urbach tail, and electron-phonon interactions in topological insulator Bi2Se3 and band insulator (Bi0.89In0.11)2Se3

2019 ◽  
Vol 114 (16) ◽  
pp. 162105 ◽  
Author(s):  
Jiajun Zhu ◽  
Yunyouyou Xia ◽  
Gang Li ◽  
Shengqiang Zhou ◽  
S. Wimmer ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Absorption Edge ◽  
Urbach Tail ◽  
Band Insulator

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

Reflectivity spectra of Eu rich EuO near the absorption edge

1979 ◽  
Vol 40 (3) ◽  
pp. 315-319 ◽  
Author(s):  
M. Escorne ◽  
A. Mauger ◽  
C. Godart ◽  
J.C. Achard
Keyword(s):  
Absorption Edge ◽  
Reflectivity Spectra
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