Temperature behavior of exciton absorption bands in layer semiconductors

2004 ◽  
Author(s):  
V. M. Kramar ◽  
N. K. Kramar ◽  
Bohdan M. Nitsowich
Keyword(s):  
Temperature Behavior ◽  
Exciton Absorption ◽  
Absorption Bands

scholarly journals Temperature behavior of optical absorption bands in colored LiF crystals

2016 ◽  
Vol 6 ◽  
pp. 74-75 ◽  
Author(s):  
Renato Fastampa ◽  
Mauro Missori ◽  
Maria Chiara Braidotti ◽  
Claudio Conti ◽  
Maria Aurora Vincenti ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Temperature Behavior ◽  
Absorption Bands

Exciton spectra in thin crystals

1967 ◽  
Vol 298 (1452) ◽  
pp. 74-96 ◽  
Keyword(s):  
Crystal Size ◽  
Crystal Thickness ◽  
Optical Absorption Edge ◽  
Exciton Absorption ◽  
Molybdenum Disulphide ◽  
Absorption Bands ◽  
Observed Behaviour ◽  
Crystal Volume ◽  
Different Thickness ◽  
Split Valence

The optical absorption edge of crystals of molybdenum disulphide consists of two series of exciton absorption bands, the A and B series, which are due to the formation of delocalized excitons by direct allowed transitions from a split valence band. In ‘thick’ crystals at 77 °K the wavenumber position v n of the absorption bands is given by V n A = 15952 − ( 364 / n 2 ) c m − 1 and V n B = 18230 − ( 1056 / n 2 ) c m − 1 . Transmission and reflexion measurements on crystals of different thickness ranging from 0∙05 to 0∙8 μ m have shown that the exciton bands move to higher energies in thin crystals as a result of the increased exciton binding energy in small crystal volume. This effect is most marked for excitons of large radii and for the larger excitons of the A series. The variation of absorption coefficient and refractive index over the exciton spectra have been measured. The oscillator strength of the A series bands varies as ca . n -3 . Absorption bands A 1 and B 1 are unaffected by the crystal size effect and their observed behaviour in thin crystals is predicted by classical optics. This includes the measured oscillation in transmission with changing crystal thickness which occurs at the peaks of the n = 1 exciton bands.

Temperature behavior of the integral intensity of exciton absorption

1983 ◽  
Vol 115 (2) ◽  
pp. K87-K90 ◽  
Author(s):  
B. M. Nitsovich ◽  
G. M. Pestryakov
Keyword(s):  
Integral Intensity ◽  
Temperature Behavior ◽  
Exciton Absorption

Polarimetric Observations of Red Variables: A Study of Gas and Particle Interactions

1979 ◽  
Vol 46 ◽  
pp. 386-408 ◽  
Author(s):  
G. V. Coyne ◽  
I. S. McLean
Keyword(s):  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Absorption And Emission ◽  
Mira Variables ◽  
Stellar Photosphere ◽  
Regular Variable ◽  
Red Supergiants ◽  
Balmer Lines

AbstractIn recent years the wavelength, dependence of the polarization in a number of Mira variables, semi-regular variables and red supergiants has been measured with resolutions between 0.3 and 300 A over the range 3300 to 11000 A. Variations are seen across molecular absorption bands, especially TiO bands, and across atomic absorption and emission lines, especially the Balmer lines. In most cases one can ignore or it is possible to eliminate the effects due to interstellar polarization, so that one can study the polarization mechanisms operating in the stellar atmosphere and environment. The stars Omicron Ceti. (Mira), V CVn (semi-regular variable) and Mu Cephei (M2 la), in addition to other stars similar to them, will be discussed in some detail.Models to explain the observed polarization consider that the continuum flux is polarized either by electron, molecular and/or grain scattering or by temperature variations and/or geometrical asymmetries over the stellar photosphere. This polarized radiation is affected by atomic and molecular absorption and emission processes at various geometric depths in the stellar atmosphere and envelope. High resolution spectropolarimetry promises, therefore, to be a power-rul tool for studying stratification effects in these stars.

Investigation of the fine structure in overtone absorption bands of 12C2H4

1999 ◽  
Vol 97 (1) ◽  
pp. 265-277 ◽  
Author(s):  
M. BACH, R. GEORGES, M. HERMAN, A. PER
Keyword(s):  
Fine Structure ◽  
Absorption Bands
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