Evidence for Complexes of Hydrogen with Impurities or Defects in Bulk III-V Materials

1987 ◽  
Vol 104 ◽  
Author(s):  
B. Clerjaud ◽  
D. Côte ◽  
M. Krause ◽  
C. Naud
Keyword(s):  
Optical Absorption ◽  
Absorption Lines ◽  
Bulk Materials ◽  
Local Modes ◽  
Modes Of Vibration

ABSTRACTSeries of sharp optical absorption lines around 2200 cm-1 in GaP, 2000 cm-1 in GaAs, and 2300 cm-1 in InP are observed in bulk materials. They are shown to be due to stretching local modes of vibration of P-H or As-H bonds, the hydrogen sitting nearby an impurity or defect. The origin of the hydrogen contamination of the bulk materials is discussed.

OPTICAL ABSORPTION SPECTRA OF ARSENIC AND PHOSPHORUS IN SILICON

1962 ◽  
Vol 40 (10) ◽  
pp. 1480-1489 ◽  
Author(s):  
J. W. Bichard ◽  
J. C. Giles
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Excited States ◽  
Ground State ◽  
Absorption Lines ◽  
Full Width ◽  
Optical Absorption Spectra ◽  
Phosphorus Impurity ◽  
Line Widths ◽  
Phosphorus In Silicon

The optical absorption spectra of arsenic and phosphorus donor impurities in silicon have been studied under conditions of improved resolution. Absorption lines due to transitions from the impurity ground state to the excited states 2p0, 2p±, 3p0, 3p±, 4p0, 4 p±, and 5p0, and 5p± have been observed at 4.2° K. The relative intensities of some of these absorption lines are compared with existing experimental and theoretical estimates. The contribution of instrumental broadening to the observed line widths is assessed and natural line widths are estimated. The estimates indicate values for the natural line widths which are much less than those previously reported. For phosphorus impurity, the natural line widths are estimated to be less than 0.08 × 10−3 electron volts full width at half-maximum. The possibility of concentration broadening is discussed in connection with the arsenic data.

scholarly journals The Absorption Line Systems of the Supershell LMC2 in the Large Magellanic Cloud

1999 ◽  
Vol 190 ◽  
pp. 154-155
Author(s):  
Adeline Caulet
Keyword(s):  
Optical Absorption ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Absorption Line ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Absorption Lines

The interstellar medium of LMC2, a well studied supershell in the Large Magellanic Cloud, has been probed in UV and optical absorption lines. The data allow to derive the kinematics, abundances and depletions of gas clouds in this supershell. The relative gas-phase abundances of observed elements with respect to sulphur are useful to determine the origins of the supershell absorption-line clouds.

scholarly journals Sub-milliarcsecond Radio Structure of AO 0235+164

1984 ◽  
Vol 110 ◽  
pp. 47-48
Author(s):  
Dayton L. Jones ◽  
Mike M. Davis ◽  
Steve C. Unwin
Keyword(s):  
Optical Absorption ◽  
Flux Density ◽  
Radio Spectrum ◽  
Absorption Lines ◽  
Radio Structure ◽  
Spectrum Radio ◽  
Bl Lac ◽  
Line Redshift ◽  
To Come ◽  
Absorption Frequencies

AO 0235+164 is a very compact, flat-spectrum radio source. It is identified with a BL Lac object, and has optical absorption-line systems at z = 0.524 and z = 0.852. A complex set of HI absorption lines is seen at z = 0.524 (932 MHz), and several of these lines change significantly in depth over periods of less than a year. This is the only known case of variable extragalactic absorption lines. A faint nebulosity 2 arcsec south of AO 0235 + 164 has an emission-line redshift of z = 0.52 and may be an intervening galaxy. The radio spectrum of this source (between major outbursts) is remarkably flat, with the total flux density staying between about 1 and 3 Jy over a range of at least 1000 in frequency. Such a flat spectrum would lead one to expect a complex, wavelength-dependent structure consisting of several components with different self-absorption frequencies. However, the observed radio structure of 0235+164 is about as simple as one could imagine – it is a nearly unresolved point source in VLBI experiments from 900 MHz to 22 GHz. Recent VLBI experiments at 6 and 13 cm have shown evidence for some elongation of the source in a generally NE-SW direction, but only at low contour levels (< 15% of the peak). The major portion of the flux density appears to come from a core which is unresolved in VLBI experiments over a range of ~ 25 in frequency.

Influence of exciton motion on the shape of optical absorption lines: Applications to vibrations at surfaces

1986 ◽  
Vol 34 (4) ◽  
pp. 2266-2283 ◽  
Author(s):  
B. N. J. Persson ◽  
F. M. Hoffmann ◽  
R. Ryberg
Keyword(s):  
Optical Absorption ◽  
Absorption Lines

Identification and Significance of the First Structural Modes of Vibration of Two Wheeled Vehicles

2010 ◽  
Author(s):  
Alberto Doria ◽  
Luca Trombetta ◽  
Roberto Pegoraro
Keyword(s):  
Modal Analysis ◽  
Rigid Bodies ◽  
Elastic Behavior ◽  
Local Modes ◽  
System Of Rigid Bodies ◽  
Swing Arm ◽  
Modes Of Vibration ◽  
Small Set ◽  
Vehicle Chassis ◽  
Motorcycle Dynamics

In motorcycles and scooters the structural modes of vibration are important because they influence both vehicle’s comfort and vehicle’s stability and handling. Some researchers have shown that instabilities, which may occur when the vehicle is running (weave and wobble), are influenced by the modes of vibration, of the vehicle. At the Motorcycle Dynamics Research Group of Padova University many motorcycles have been tested with the method of modal analysis. The results of this research highlight that the whole motorcycle is a complex system that shows many kinds of modes of vibration: rigid modes, in which the structural components of the vehicle (chassis, fork, handlebars) behave as rigid bodies and deflection is given by tires and suspensions; local modes, in which deflection is concentrated in some subsystem of the vehicle (e.g. handlebars) and the rest of the motorcycle behaves as a system of rigid bodies; global modes with relevant deflection of the whole vehicle. This paper focuses on a specific issue, which is important for motorcycle design: the identifications of the frequencies of the first modes that show relevant deflection of the front fork and swing-arm. First, experimental equipment and testing methods are presented and discussed. Then the modal properties (natural frequencies, damping coefficients and modal shapes) of four motorcycles of different categories are presented, the characteristics of some modes are highlighted. Finally, the paper focuses on the identification of the frequencies that represent the borderline between rigid and elastic behavior of front fork and swing-arm. A method that requires the analysis of the characteristics of a small set of frequency response functions, without carrying out a long and expensive modal analysis of the whole vehicle, is presented. It is based on the properties of rigid modes (variation in vibration amplitude along a set of measurement points).

Optical absorption lines in the spectrum of the quasar 3C 286

1979 ◽  
Vol 232 ◽  
pp. 54 ◽  
Author(s):  
H. Spinrad ◽  
C. F. McKee
Keyword(s):  
Optical Absorption ◽  
Absorption Lines

Hyperfine structure of 127I2 and 129I2 optical absorption lines

1980 ◽  
Vol 33 (1) ◽  
pp. 23-25 ◽  
Author(s):  
J.P. Pique ◽  
F. Stoeckel ◽  
F. Hartmann
Keyword(s):  
Optical Absorption ◽  
Hyperfine Structure ◽  
Absorption Lines
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