Optical Absorption of Deep Defects in Neutron Irradiated Semi-Insulating GaAs.

1989 ◽  
Vol 163 ◽  
Author(s):  
M. O. Manasreh ◽  
P. J. Pearah
Keyword(s):  
Optical Absorption ◽  
Thermal Neutron ◽  
Infrared Absorption ◽  
White Light ◽  
Monochromatic Light ◽  
Annealing Conditions ◽  
Lec Gaas ◽  
Order Of Magnitude ◽  
Insulating Liquid ◽  
Absorption Technique

AbstractTwo defects were observed in thermal neutron irradiated semi-insulating liquid-encapsulated Czochralski (LEC) GaAs materials by using the infrared absorption technique. The first defect was observed before thermal annealing and it has a broad peak at ~0.83 eV. The second defect was observed after annealing the sample at 250 °C for 15 min. The latter defect is an EL2 - like defect, but is thermally unstable at 400 °C with a concentration of about an order of magnitude larger than [EL2] observed in as grown LEC materials. Both defects were found to photoquench with white light or 1.1 eV monochromatic light at 9 K and thermally recovered at 150 K. The concentration of the EL2 - like defect is reduced from 8.5×1016cm3 after annealing the sample at 300 °C for 15 min to 2×1016cm-3 after annealing at 400 °C for 15 min. This defect becomes unquenchable after the latter annealing conditions. An explanation for this behavior is offered.

SPM Characterization of Substrate Surfaces Prepared for Carbon-Related-Film Deposition

1999 ◽  
Vol 587 ◽  
Author(s):  
Kazumasa Narumi ◽  
Shunya Yamamoto ◽  
Hiroshi Naramoto
Keyword(s):  
Annealing Temperature ◽  
Temperature Characteristic ◽  
Film Deposition ◽  
Annealing Conditions ◽  
Atomic Force ◽  
Surface Steps ◽  
Order Of Magnitude ◽  
Reducing Environment ◽  
Substrate Surfaces

AbstractsVariation of surface steps on sapphire (0001) and (1120) substrates processed with thermal annealing in air or a reducing environment at 1000 to 1400°C for 1 to 10 hours were investigated with an atomic force microscope (AFM). The annealed (0001) surfaces consist of atomically smooth and large terraces and atomic-height steps, whose configurations strongly depend on annealing conditions. On the (1120) surfaces, where crystallographic misorientation is almost an order of magnitude larger than that of the (0001) surfaces, step height and terraces increase in size with the longer annealing time and higher annealing temperature. Characteristic step figures due to the symmetry of atomic arrangement were observed on the (0001) surface.

Soot in Urban Atmospheres: Determination by an Optical Absorption Technique

Science ◽  
1980 ◽  
Vol 208 (4445) ◽  
pp. 741-744 ◽  
Author(s):  
H. ROSEN ◽  
A. D. A. HANSEN ◽  
R. L. DOD ◽  
T. NOVAKOV
Keyword(s):  
Optical Absorption ◽  
Absorption Technique ◽  
Urban Atmospheres

scholarly journals Towards white-light generation through upconversion of low-power near-infrared photons

RSC Advances ◽  
2017 ◽  
Vol 7 (26) ◽  
pp. 16126-16130 ◽  
Author(s):  
Oleg P. Dimitriev ◽  
Julia L. Bricks ◽  
Anna L. Smirnova ◽  
Yuri L. Slominskii
Keyword(s):  
Low Power ◽  
Infrared Absorption ◽  
White Light ◽  
Near Infrared ◽  
Dye Molecules ◽  
White Light Generation ◽  
Light Generation

A broadband upconverted emission combined with a broadband infrared absorption takes place in films composed of the same infrared dye molecules.

scholarly journals Optical Absorption Spectra of H2O Ice Doped with Ytterbium Chloride YbCl3

1978 ◽  
Vol 21 (85) ◽  
pp. 559-563
Author(s):  
L. Couture
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Near Infrared ◽  
Dilute Solution ◽  
Optical Absorption Spectra ◽  
Stark Splitting ◽  
Ytterbium Chloride ◽  
Infrared Absorption Spectra ◽  
Frozen Solutions

AbstractNear-infrared absorption spectra of a frozen dilute solution of ytterbium chloride have been obtained at 77 K, 20 K, and 4.2 K. They contain two broad lines revealing a Stark splitting of 60 cm-1 of the excited 2F5/2, level of the Yb3+ ion. Such spectra indicate that in frozen solutions of ytterbium chloride the Yb3+ ions have crystalline or quasi-crystalline surroundings which are similar for most ions; different possibilities are discussed.

scholarly journals Spectral Tuning of White Light Allows for Strong Reduction in Melatonin Suppression without Changing Illumination Level or Color Temperature

2018 ◽  
Vol 33 (4) ◽  
pp. 420-431 ◽  
Author(s):  
Jan L. Souman ◽  
Tobias Borra ◽  
Iris de Goijer ◽  
Luc J. M. Schlangen ◽  
Björn N. S. Vlaskamp ◽  
...  
Keyword(s):  
White Light ◽  
High Power ◽  
Spectral Power ◽  
Monochromatic Light ◽  
Action Spectrum ◽  
Color Temperature ◽  
Light Spectrum ◽  
Melatonin Suppression ◽  
Dim Light ◽  
Melatonin Production

Studies with monochromatic light stimuli have shown that the action spectrum for melatonin suppression exhibits its highest sensitivity at short wavelengths, around 460 to 480 nm. Other studies have demonstrated that filtering out the short wavelengths from white light reduces melatonin suppression. However, this filtering of short wavelengths was generally confounded with reduced light intensity and/or changes in color temperature. Moreover, it changed the appearance from white light to yellow/orange, rendering it unusable for many practical applications. Here, we show that selectively tuning a polychromatic white light spectrum, compensating for the reduction in spectral power between 450 and 500 nm by enhancing power at even shorter wavelengths, can produce greatly different effects on melatonin production, without changes in illuminance or color temperature. On different evenings, 15 participants were exposed to 3 h of white light with either low or high power between 450 and 500 nm, and the effects on salivary melatonin levels and alertness were compared with those during a dim light baseline. Exposure to the spectrum with low power between 450 and 500 nm, but high power at even shorter wavelengths, did not suppress melatonin compared with dim light, despite a large difference in illuminance (175 vs. <5 lux). In contrast, exposure to the spectrum with high power between 450 and 500 nm (also 175 lux) resulted in almost 50% melatonin suppression. For alertness, no significant differences between the 3 conditions were observed. These results open up new opportunities for lighting applications that allow for the use of electrical lighting without disturbance of melatonin production.

Physical and Mathematical Considerations About Laser Perimetry

1974 ◽  
Vol 23 (S1) ◽  
pp. 349-351 ◽  
Author(s):  
L. Favella ◽  
L. Liuzzi ◽  
F. Bartoli
Keyword(s):  
White Light ◽  
Laser Light ◽  
Monochromatic Light ◽  
Neon Laser ◽  
Helium Neon Laser ◽  
Helium Neon ◽  
Mathematical Characteristics

The physical and mathematical characteristics of white light, monochromatic light, and laser light, are discussed with reference to the advantages offered by perimetry using a red helium-neon laser.

OPTICAL SPECTROSCOPY AND NONLINEAR TRANSMITTANCE STUDY OF FULLERENE C60 IN MIXTURES WITH 2-CYCLOOCTYLAMINO-5-NITROPYRIDINE (COANP)

2004 ◽  
Vol 13 (01) ◽  
pp. 113-127 ◽  
Author(s):  
SERGEY S. SARKISOV ◽  
ELENA I. RADOVANOVA ◽  
BURL H. PETERSON ◽  
ALEX LEYDERMAN ◽  
MICHAEL CURLEY ◽  
...  
Keyword(s):  
Optical Properties ◽  
Absorption Spectrum ◽  
Optical Absorption ◽  
Infrared Absorption ◽  
Chemical Bonding ◽  
Infrared Absorption Spectrum ◽  
Visible Region ◽  
Fullerene C60 ◽  
Amino Group

Characterization of the infrared absorption spectrum of the solutions of fullerene C 60 with 2-cyclooctylamino-5-nitropyridine additive has been performed with the focus on possible bonding with the amino-group of the additive. No occurrence of such bonding was found at normal conditions. Also no change of optical absorption in visible region and optical limiting of fullerene due to chemical bonding with the additive was detected. The resulting optical properties of the mixture were simply a sum of the properties of the components for a molar proportion of the additive to fullerene approaching 200:1.

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