Absorption saturable de HITC

1976 ◽  
Vol 54 (14) ◽  
pp. 1449-1453 ◽  
Author(s):  
M. Saenz de la Calzada ◽  
H. Lam ◽  
M. M. Denariez-Roberge
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Theoretical Models ◽  
Incident Pulse ◽  
Experimental Results ◽  
Absorption Cross ◽  
Good Agreement

We measured the variation of the transmission of solutions of HITC in different solvents as a function of the intensity and duration of the incident pulse. Good agreement is found between our experimental results and the theoretical models proposed by Hercher. The absorption cross section at 6943 Å of the excited first singlet levels is deduced from these measurements. Some applications of the results are discussed.

FINE STRUCTURE IN THE O16(γ, n)O15 YIELD CURVE

1959 ◽  
Vol 37 (12) ◽  
pp. 1357-1364 ◽  
Author(s):  
H. King ◽  
L. Katz
Keyword(s):  
Fine Structure ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Yield Curve ◽  
Photon Absorption ◽  
Experimental Techniques ◽  
Absorption Cross ◽  
Good Agreement ◽  
Near Threshold

Fine structure in the OI6(γ, n)O15 yield curve near threshold was examined using improved experimental techniques. Breaks were observed at threshold, 15.85, 16.14, 16.45, 16.74, 16.88, 17.05, 17.15, and 17.21 Mev. These energies are established to within ± 0.04 Mev. The integrated photon absorption cross section in these breaks resulting in (γ, n) reactions was found to be 0.47 ± 0.11 Mev-mb. Our results are in good agreement with the measurements of other workers.

A direct measurement of the thermal neutron conversion ratio of natural uranium

1969 ◽  
Vol 47 (12) ◽  
pp. 1317-1325 ◽  
Author(s):  
C. B. Bigham ◽  
R. W. Durham ◽  
J. Ungrin
Keyword(s):  
Thermal Neutron ◽  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Direct Method ◽  
Natural Uranium ◽  
Conversion Ratio ◽  
Absorption Cross ◽  
A Direct Method ◽  
Good Agreement

A direct method for measuring the thermal neutron conversion ratio of natural uranium (capture in 238U)/(destruction of 235U), gives 0.5655 ± 0.0025 (20 °C Maxwellian) in good agreement with 0.565 ± 0.009 from the separately measured cross sections. The corresponding value for the 2200 m/s absorption cross section of 238U is 2.721 ± 0.016 b. The method is based on the use of a sample of 243Am, which α-decays to 239Np, for correlating the efficiencies of the fission counter and γ counter used to measure the number of fissions and the amount of 239Np produced during an irradiation of a natural uranium sample.

scholarly journals Photoelectric absorption cross section of silicon near the bandgap from room temperature to sub-Kelvin temperature

AIP Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 025120
Author(s):  
C. Stanford ◽  
M. J. Wilson ◽  
B. Cabrera ◽  
M. Diamond ◽  
N. A. Kurinsky ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Room Temperature ◽  
Absorption Cross ◽  
Photoelectric Absorption

scholarly journals Ultraviolet Absorption Cross-Sections of Ammonia at Elevated Temperatures for Nonintrusive Quantitative Detection in Combustion Environments

2021 ◽  
pp. 000370282199044
Author(s):  
Wubin Weng ◽  
Shen Li ◽  
Marcus Aldén ◽  
Zhongshan Li
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Elevated Temperatures ◽  
Uv Absorption ◽  
Energy Utilization ◽  
Quantitative Detection ◽  
Absorption Cross ◽  
Hot Gas

Ammonia (NH3) is regarded as an important nitrogen oxides (NOx) precursor and also as an effective reductant for NOx removal in energy utilization through combustion, and it has recently become an attractive non-carbon alternative fuel. To have a better understanding of thermochemical properties of NH3, accurate in situ detection of NH3 in high temperature environments is desirable. Ultraviolet (UV) absorption spectroscopy is a feasible technique. To achieve quantitative measurements, spectrally resolved UV absorption cross-sections of NH3 in hot gas environments at different temperatures from 295 K to 590 K were experimentally measured for the first time. Based on the experimental results, vibrational constants of NH3 were determined and used for the calculation of the absorption cross-section of NH3 at high temperatures above 590 K using the PGOPHER software. The investigated UV spectra covered the range of wavelengths from 190 nm to 230 nm, where spectral structures of the [Formula: see text] transition of NH3 in the umbrella bending mode, v2, were recognized. The absorption cross-section was found to decrease at higher temperatures. For example, the absorption cross-section peak of the (6, 0) vibrational band of NH3 decreases from ∼2 × 10−17 to ∼0.5 × 10−17 cm2/molecule with the increase of temperature from 295 K to 1570 K. Using the obtained absorption cross-section, in situ nonintrusive quantification of NH3 in different hot gas environments was achieved with a detection limit varying from below 10 parts per million (ppm) to around 200 ppm as temperature increased from 295 K to 1570 K. The quantitative measurement was applied to an experimental investigation of NH3 combustion process. The concentrations of NH3 and nitric oxide (NO) in the post flame zone of NH3–methane (CH4)–air premixed flames at different equivalence ratios were measured.

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