scholarly journals Excitation Processes in Cometary Comae

1987 ◽  
Vol 120 ◽  
pp. 455-459
Author(s):  
P. D. Singh
Keyword(s):  
Electron Recombination ◽  
Recombination Processes ◽  
Excitation Processes ◽  
Cometary Comae

Excitations of cometary NH and S2 molecules are discussed. Photodissociation and dissociative electron recombination processes may be sources of meta-stable nitrogen (2Po, 2Do) atoms in comets.

scholarly journals The origin of slow electron recombination processes in dye-sensitized solar cells with alumina barrier coatings

2004 ◽  
Vol 96 (11) ◽  
pp. 6903-6907 ◽  
Author(s):  
Francisco Fabregat-Santiago ◽  
Jorge García-Cañadas ◽  
Emilio Palomares ◽  
John N. Clifford ◽  
Saif A. Haque ◽  
...  
Keyword(s):  
Solar Cells ◽  
Dye Sensitized Solar Cells ◽  
Slow Electron ◽  
Electron Recombination ◽  
Barrier Coatings ◽  
Dye Sensitized ◽  
Recombination Processes ◽  
Sensitized Solar Cells

scholarly journals Two- and Three-body Ion-Electron Recombination Rate Coefficients in Neon

1995 ◽  
Vol 48 (3) ◽  
pp. 503 ◽  
Author(s):  
RN Bhave ◽  
R Cooper
Keyword(s):  
Recombination Rate ◽  
Rate Coefficient ◽  
Rate Coefficients ◽  
Electron Recombination ◽  
Wide Range ◽  
Recombination Processes ◽  
Three Body ◽  
Modified Theory ◽  
Body Recombination ◽  
Monatomic Gas

The rates of recombination of electrons with Net ions over a wide range of pressure (1001000 Torr) and at temperatures of 133, 233 and 295 K were measured. Two- and three-body recombination processes were resolved. The observed two-body rate coefficient is lower than earlier reports. The three-body rate measured agrees well with predictions from Flarinery's modified theory by Bates for termolecular ion-electron recombination in a monatomic gas.

The effect of electron recombination processes on the luminescence kinetics of ZnO ceramics

2015 ◽  
Vol 118 (3) ◽  
pp. 425-430 ◽  
Author(s):  
K. A. Chernenko ◽  
L. Grigor’eva ◽  
E. I. Gorokhova ◽  
P. A. Rodnyi
Keyword(s):  
Electron Recombination ◽  
Luminescence Kinetics ◽  
Recombination Processes ◽  
Kinetics Of ◽  
Zno Ceramics

scholarly journals High-Resolution Optical and Infrared Observations of Molecules in Comets

2000 ◽  
Vol 197 ◽  
pp. 471-480 ◽  
Author(s):  
S. J. Kim ◽  
Y. C. Minh ◽  
S. Hyung ◽  
Y. H. Kim
Keyword(s):  
High Resolution ◽  
Solar Nebula ◽  
Solar System Formation ◽  
Cometary Nuclei ◽  
Infrared Observations ◽  
Spectroscopic Observations ◽  
Radio Range ◽  
Excitation Processes ◽  
Molecular Abundances ◽  
Cometary Comae

Molecules in cometary nuclei are considered to contain information on the constituents in the proto-solar nebula at the time of solar system formation. The composition of cometary nuclei has been indirectly derived from spectroscopic observations of molecules in comae. Ambitious space missions to cometary nuclei for landing and sample return are planned to be realized in 4–7 years. Until then, spectroscopic observations remain a powerful way to remotely investigate molecules and ions in cometary comae. Recent bright comets such as Hale-Bopp (C/1995 O1) and Hyakutake (C/1996 B2) have provided detections of new molecules in comae. Observational results from high-resolution optical and infrared spectroscopy of Hale-Bopp, Hyakutake and recent comets, are presented. In particular, symmetric molecules, which have zero electric dipole moment and are therefore not observable in the radio range, have been detected in several recent comets by infrared observations. The new data can also be used to derive accurate abundances of known molecular species. We present the time-dependent excitation processes of the bands of these molecules and discuss the influence of the fluorescence calculations on the derivations of molecular abundances in comets.

scholarly journals The Formation of Optical CNO Emission Lines in Cataclysmic Variables

1983 ◽  
Vol 72 ◽  
pp. 97-115
Author(s):  
Robert E. Williams ◽  
Donald H. Ferguson
Keyword(s):  
Binary Systems ◽  
Cataclysmic Variables ◽  
Emission Lines ◽  
Resonance Fluorescence ◽  
Continuum Radiation ◽  
Spectroscopic Observations ◽  
Recombination Processes ◽  
Excitation Processes

ABSTRACTSpectroscopic observations of CNO emission lines are presented for old nova systems, and possible excitation processes for the lines are considered. The Bowen fluorescence mechanism cannot generally be responsible for the strength of N III λ4640 because of the weakness of 0 III λ3429. Other CNO lines are observed which indicate that all of the lines are excited by resonance fluorescence of UV continuum radiation. Several nonfluorescent excited lines of carbon are also present in old novae, probably formed by recombination processes. The available data for the optical CNO lines suggest that non-solar CNO enhancements exist in quiescent novae, indicating that some of the binary systems may be evolved.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

Plasma parameters in atomic-emission spectral analysis of phosphate concentrates of the fission products

2019 ◽  
Vol 85 (2) ◽  
pp. 17-22
Author(s):  
M. I. Khamdeev ◽  
E. A. Erin
Keyword(s):  
Spectral Analysis ◽  
Chemical Composition ◽  
Reference Materials ◽  
Fission Products ◽  
Atomic Emission ◽  
Electric Arc ◽  
Physical Parameters ◽  
Arc Plasma ◽  
Atomic Emission Spectral Analysis ◽  
Excitation Processes

Physical parameters of electric arc plasma as well as their time dependences are calculated when analyzing phosphate precipitates of the fission products of irradiated nuclear fuel. Phosphate concentrates of the fission products are known for their complex chemical composition and high thermal and chemical stability. Hence, direct atomic emission spectral analysis of phosphate powders without transferring them into solutions is advisable. Different conditions of sample preparation and synthesis of the reference materials determine the different chemical forms of the elements to be determined. This, in turn, affects the kinetics of their evaporation in the electrode crate and excitation processes in the plasma. The known mechanisms of those processes cannot always be transferred to specific conditions of the given method of analysis thus entailing the necessity of studying the effect of the samples chemical composition on the results of determination, proper choice of spectroscopic carriers, detailed study of spectra excitation processes in spectral analysis, and analysis of the physical parameters of the electric arc plasma. We used the lines Zn I 307.206 nm and Zn I 307.589 nm to measure the effective temperature of the central hot sections of the arc in a range of4500 - 6500 K. NaCl, BaCl2 and NaCl + T1C1 were studied to reduce the effect of the sample elemental composition on excitation conditions of the spectra and their stabilization as a spectroscopic carrier. In control experiments we used carrier-free samples. The coincidence of the values of the plasma physical parameters within the measurement error not exceeding 20%, as well as the identity of the nature of the kinetic curves for samples of phosphate precipitates and synthetic reference materials prove their correctness. The result of the study substantiate correctness of the direct atomic-emission spectral procedure in analysis of phosphate concentrates of fission when using synthetic reference materials.

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