scholarly journals Taming microwave plasma to beat thermodynamics in CO2 dissociation

2015 ◽  
Vol 183 ◽  
pp. 233-248 ◽  
Author(s):  
G. J. van Rooij ◽  
D. C. M. van den Bekerom ◽  
N. den Harder ◽  
T. Minea ◽  
G. Berden ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Microwave Plasma ◽  
Vibrational Excitation ◽  
Distribution Functions ◽  
Dissociative Excitation ◽  
Plasma Dynamics ◽  
Novel Approach ◽  
Process Energy ◽  
Energy Distribution Functions ◽  
Non Equilibrium

The strong non-equilibrium conditions provided by the plasma phase offer the opportunity to beat traditional thermal process energy efficiencies via preferential excitation of molecular vibrations. Simple molecular physics considerations are presented to explain potential dissociation pathways in plasma and their effect on energy efficiency. A common microwave reactor approach is evaluated experimentally with Rayleigh scattering and Fourier transform infrared spectroscopy to assess gas temperatures (exceeding 104 K) and conversion degrees (up to 30%), respectively. The results are interpreted on a basis of estimates of the plasma dynamics obtained with electron energy distribution functions calculated with a Boltzmann solver. It indicates that the intrinsic electron energies are higher than is favorable for preferential vibrational excitation due to dissociative excitation, which causes thermodynamic equilibrium chemistry to dominate. The highest observed energy efficiencies of 45% indicate that non-equilibrium dynamics had been at play. A novel approach involving additives of low ionization potential to tailor the electron energies to the vibrational excitation regime is proposed.

Gas phase photolysis of 1-pentene and 1-pentene-d10 at 7.1 and 7.6 eV. Kinetic considerations

1978 ◽  
Vol 56 (10) ◽  
pp. 1435-1441 ◽  
Author(s):  
Andrzej Więckowski ◽  
Guy J. Collin
Keyword(s):  
Gas Phase ◽  
Isotope Effects ◽  
Distribution Functions ◽  
Static System ◽  
Hydrogen Atoms ◽  
Photochemical Process ◽  
Radical Decomposition ◽  
Energy Distribution Functions ◽  
Kinetics Of ◽  
Non Equilibrium

The gas phase photolysis of n-pentene was carried out in a static system using nitrogen resonance lines at [Formula: see text] and the bromine line at [Formula: see text] The mechanism for the photolysis was proposed and compared to what was concluded at 8.4 eV (147 nm, the xenon resonance line). The kinetics of the decomposition of the excited C3H5* radicals formed in the primary photochemical process and the C5H11* radicals formed by the addition of hydrogen atoms to the parent molecules were discussed. The investigations were extended to the n-C5D10 photolytic System. The observed decomposition rate constants of the excited pentyl radicals as well as the secondary non-equilibrium isotope effects agree with the data published earlier. It is concluded from these experiments that, at least at 7.6 eV, hot hydrogen atoms are produced.Only a small fraction of the C3H5* radicals décompose and yield aliène. At the same time the combined primary–secondary non-equilibrium isotope effects are much less than those calculated for the 'pure' primary isotope effects. To account for these observations, it is assumed that the C3H5* radicals are formed with a wide spread in the internal energies. Since the threshold of the decomposition of the excited C3H5* radical lies above its mean excess energy (calculated on the statistical basis), an analogy in the energy-distribution functions on the radicals activated photochemically and thermally may be suggested. If so, an inverse secondary isotope effect may contribute to the gross effect involved in the C3H5* radical decomposition.

Effect of ion Bombardment in Polymer Surface Modification: Comparison of Pulsed High Frequency Plasma and ion Beam

1998 ◽  
Vol 544 ◽  
Author(s):  
O. Zabeida ◽  
J. E. Klemberg-Sapieha ◽  
L. Martinu ◽  
D. Morton
Keyword(s):  
Microwave Plasma ◽  
Ion Beam ◽  
Plasma Reactor ◽  
Polymer Surface ◽  
Ion Bombardment ◽  
Ion Source ◽  
Distribution Functions ◽  
Surface Restructuring ◽  
Microstructure Density ◽  
Energy Distribution Functions

AbstractThe energy and the flux of impinging ions are important factors which determine the properties of deposited films and of exposed surfaces (microstructure, density, hardness, roughness, stress, chemical structure, adhesion etc.). In the present work, we use a multigrid retarding field analyzer to study ion bombardment characteristics in two different systems: a pulsed microwave plasma reactor, and a cold cathode ion source. We have found that the ion energy distribution functions (IEDF) possess specific features for each mode of operation: we evaluate the shape and the maximum and the mean ion energies of the IEDF for different gases such as Ar and N2. These ion characteristics are correlated with surface restructuring of differently treated polymers (polycarbonate and polyethylene terephthalate), analyzed by XPS.

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