On the Emission and Absorption Wave-Lengths of the Characteristic Radiation in the L-Series.

1921 ◽  
Vol 18 (3) ◽  
pp. 218-220 ◽  
Author(s):  
D. Coster
Keyword(s):  
Characteristic Radiation ◽  
Absorption Wave

Contribution of x-ray total reflection to the background intensity in EPMA

1990 ◽  
Vol 48 (2) ◽  
pp. 202-203
Author(s):  
Werner P. Rehbach ◽  
Peter Karduck
Keyword(s):  
Atomic Number ◽  
Target Material ◽  
Total Reflection ◽  
Background Intensity ◽  
X Rays ◽  
Characteristic Radiation ◽  
X Ray

In the EPMA of soft x rays anomalies in the background are found for several elements. In the literature extremely high backgrounds in the region of the OKα line are reported for C, Al, Si, Mo, and Zr. We found the same effect also for Boron (Fig. 1). For small glancing angles θ, the background measured using a LdSte crystal is significantly higher for B compared with BN and C, although the latter are of higher atomic number. It would be expected, that , characteristic radiation missing, the background IB (bremsstrahlung) is proportional Zn by variation of the atomic number of the target material. According to Kramers n has the value of unity, whereas Rao-Sahib and Wittry proposed values between 1.12 and 1.38 , depending on Z, E and Eo. In all cases IB should increase with increasing atomic number Z. The measured values are in discrepancy with the expected ones.

Oliver Heaviside: an accidental time traveller

2018 ◽  
Vol 376 (2134) ◽  
pp. 20170448
Author(s):  
Paul J. Nahin
Keyword(s):  
Cherenkov Radiation ◽  
Charged Particles ◽  
Electromagnetic Theory ◽  
Time Travel ◽  
Characteristic Radiation ◽  
Theme Issue ◽  
The Past ◽  
Faster Than Light

A little discussed aspect of Heaviside's work in electromagnetics concerned faster-than-light (FTL) charged particles, precursors to the hypothetical tachyon and his discovery that such motion should produce a characteristic radiation signature (now called Cherenkov radiation ). When Heaviside wrote, the time travel implications of FTL were not known (Einstein was still a teenager), and in this paper some speculations are offered on what Heaviside would have thought of FTL time travel, and of the associated (now classic) time travel paradoxes, including the possibility (or not) of sending information into the past. This article is part of the theme issue ‘Celebrating 125 years of Oliver Heaviside's ‘Electromagnetic Theory’’.

The Dielectric Discharge as an Efficient Generator of Active Nitrogen for Chemiluminescence and Analysis

1983 ◽  
Vol 37 (6) ◽  
pp. 545-552 ◽  
Author(s):  
John Kishman ◽  
Eric Barish ◽  
Ralph Allen
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Band System ◽  
Electrothermal Atomization ◽  
Characteristic Radiation ◽  
Gaseous Species ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Excited Species ◽  
Intense Emission

A predominantly blue “active nitrogen” afterglow was generated in pure flowing nitrogen or in air by using a dielectric discharge at pressures from 1 to 20 Torr. The afterglow contains triplet state molecules and vibrationally excited ground state molecules. These species are produced directly by electron impact without the formation and recombination of nitrogen atoms. The most intense emission is the N2 second positive band system. The N2 first positive and N2+ first negative systems are also observed. The spectral and electrical properties of this discharge are discussed in order to establish guidelines for the analytical use of the afterglow for chemiluminescence reactions. The metastatic nitrogen efficiently transfers its energy to atomic and molecular species which are introduced into the gas phase and these excited species emit characteristic radiation. The effects of electrothermal atomization of Zn and the introduction of gaseous species (e.g., NO) on the afterglow are described.

Theoretical analysis of terahertz generation in periodically inverted nonlinear crystals based on cascaded difference frequency generation process

2015 ◽  
Vol 29 (02) ◽  
pp. 1450263 ◽  
Author(s):  
Chen-Fei Hu ◽  
Kai Zhong ◽  
Jia-Lin Mei ◽  
Mao-Rong Wang ◽  
Shi-Bei Guo ◽  
...  
Keyword(s):  
Gallium Phosphide ◽  
Wave Equations ◽  
Difference Frequency Generation ◽  
Pump Intensity ◽  
Difference Frequency ◽  
Generation Process ◽  
Coupled Wave Equations ◽  
Wave Vector Mismatch ◽  
Frequency Generation ◽  
Absorption Wave

The characteristics of terahertz (THz) generation based on cascaded difference frequency generation (DFG) process in periodically inverted gallium arsenide ( GaAs ) and gallium phosphide ( GaP ) is calculated from coupled wave equations, in which the output enhancement factors are 5.4 and 3.9 in the two crystals, respectively, compared with DFG without cascading. The optimal interaction length, influence of crystal absorption, wave vector mismatch and pump intensity are analyzed. A short discussion on wavelength tuning is also given. The calculated optimal operating parameters and conclusions can provide good directions for the experimental design.

Effect of laser ablation plasma on dynamics of a laser absorption wave in a gas

1997 ◽  
Author(s):  
Vladimir N. Anisimov ◽  
Valeria G. Grishina ◽  
Oleg N. Derkach ◽  
Dmitry D. Malyta ◽  
Andrey Y. Sebrant
Keyword(s):  
Laser Ablation ◽  
Laser Absorption ◽  
Ablation Plasma ◽  
Laser Ablation Plasma ◽  
Absorption Wave

Analyzing Composite Materials by Characteristic Radiation

2018 ◽  
Vol 81 (10) ◽  
pp. 1506-1508
Author(s):  
Yu. M. Burmistrov ◽  
S. V. Zuyev ◽  
M. N. Lifanov ◽  
V. M. Skorkin
Keyword(s):  
Composite Materials ◽  
Characteristic Radiation

A 3D Numerical Wave Tank for Coastal Engineering Studies

2017 ◽  
Vol 372 ◽  
pp. 1-10 ◽  
Author(s):  
Eric Didier ◽  
Paulo R.F. Teixeira ◽  
Maria Graça Neves
Keyword(s):  
Wave Tank ◽  
Active Absorption ◽  
Wave Flume ◽  
Long Time ◽  
Mean Water Level ◽  
Wave Maker ◽  
Numerical Beach ◽  
2D And 3D ◽  
3D Applications ◽  
Absorption Wave

This paper presents the validation of active and passive, made by a dissipation beach, numerical absorbing methods implemented in RANS-VOF FLUENT® code for modelling long time series of wave propagation interacting with coastal structures. Verification of both numerical techniques was performed in 2D – wave flume, and 3D – wave tank, this one using a multiple active absorption wave makers. The active absorption wave maker allows maintaining the incident wave generation and the mean water level along the time. Good results were obtained for 2D and 3D applications for active absorption wave maker at the generation boundary and both numerical beach and active absorption at the end of the flume/tank.

X-ray Intensities from Copper-Target Diffraction Tubes

1976 ◽  
Vol 20 ◽  
pp. 565-574
Author(s):  
M. A. Short
Keyword(s):  
Close Agreement ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
X Ray Diffraction ◽  
Characteristic Radiation ◽  
Tube Voltage ◽  
X Ray ◽  
Copper Target ◽  
Fine Focus ◽  
Constant Potential

The relative intensities of the Kα characteristic radiation obtained from copper-target X-ray diffraction tubes have been calculated for a range of tube accelerating voltages and take-off angles. The calculations employ an over-voltage function, and absorption and atomic number corrections similar to those used in electron microprobe analysis. They apply only to constant potential X-ray generators. Measurements of actual intensities obtained on a Picker diffractometer using a sodium chloride monochromator gave relative intensities in close agreement with those calculated. The calculations and measurements show that there is an optimum tube voltage, with respect to intensity, for each take-off angle. This voltage increases with increasing take-off angle. The application of these results to the consideration of the relative intensities obtainable from broad, standard and fine focus copper-target X-ray diffraction tubes is discussed.

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