Chemical reaction in electric discharge. V. Reaction kinetics in a low frequency modulated discharge

1979 ◽  
Vol 57 (7) ◽  
pp. 785-795 ◽  
Author(s):  
John N. Smith ◽  
Motilal D. Costa ◽  
Jacques M. Deckers
Keyword(s):  
Glow Discharge ◽  
Reaction Mechanisms ◽  
Low Frequency ◽  
Modulation Method ◽  
Current Modulation ◽  
Kinetic Information ◽  
Glow Discharges ◽  
Dc Discharge ◽  
A Current

A current modulation technique has been developed for the determination of kinetic information in glow discharges through flowing gases. A low frequency sinusoidal modulation superimposed on the dc discharge current produces modulations in the electron density and radical concentrations. Measurements of the amplitudes and phase shifts of radical concentrations can be used to elucidate reaction mechanisms and to determine rate constants for some reaction processes.The kinetic response of discharge chemical phenomena to an applied current modulation is discussed for several general types of reaction mechanisms. Rates of O atom production and removal measured in a current modulated O2 glow discharge are compared to rates measured in a dc glow discharge. The excellent agreement of these two sets of results provides an experimental foundation for the current modulation method.

Determination of Complex Reaction Mechanisms

2006 ◽  
Author(s):  
John Ross ◽  
Igor Schreiber ◽  
Marcel O. Vlad
Keyword(s):  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Reaction Pathway ◽  
Chemical Species ◽  
Rate Coefficients ◽  
Chemical System ◽  
Evolutionary Development ◽  
Complex Reaction ◽  
Oscillatory Reactions

In a chemical system with many chemical species several questions can be asked: what species react with other species: in what temporal order: and with what results? These questions have been asked for over one hundred years about simple and complex chemical systems, and the answers constitute the macroscopic reaction mechanism. In Determination of Complex Reaction Mechanisms authors John Ross, Igor Schreiber, and Marcel Vlad present several systematic approaches for obtaining information on the causal connectivity of chemical species, on correlations of chemical species, on the reaction pathway, and on the reaction mechanism. Basic pulse theory is demonstrated and tested in an experiment on glycolysis. In a second approach, measurements on time series of concentrations are used to construct correlation functions and a theory is developed which shows that from these functions information may be inferred on the reaction pathway, the reaction mechanism, and the centers of control in that mechanism. A third approach is based on application of genetic algorithm methods to the study of the evolutionary development of a reaction mechanism, to the attainment given goals in a mechanism, and to the determination of a reaction mechanism and rate coefficients by comparison with experiment. Responses of non-linear systems to pulses or other perturbations are analyzed, and mechanisms of oscillatory reactions are presented in detail. The concluding chapters give an introduction to bioinformatics and statistical methods for determining reaction mechanisms.

Simplified and rapid determination of Ca, K, Mg, and Na in fruit juices by flowing liquid cathode atmospheric glow discharge optical emission spectrometry

2021 ◽  
Author(s):  
Monika Gorska ◽  
Pawel Pohl
Keyword(s):  
Glow Discharge ◽  
Rapid Determination ◽  
Optical Emission ◽  
Fruit Juices ◽  
Emission Spectrometry ◽  
Atmospheric Pressure Glow Discharge ◽  
Flowing Liquid ◽  
Liquid Cathode ◽  
Pressure Glow Discharge

Atmospheric pressure glow discharge (APGD) microplasma, sustained between a flowing liquid cathode (FLC) and a tungsten anode, was applied for the determination of Ca, K, Mg, and Na in fruit juices with a simplified sample preparation procedure.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

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