In this paper, we describe the principles of operation of a plasma display panel (PDP) and the physical mechanisms controlling the performances of a PDP in terms of light emission efficiency, lifetime and image quality Emphasis is put on the physics of the plasma occurring in a PDP cell, on the discharge optimization, and on the analysis of recent results provided by experimental and numerical diagnostic tools We focus on alternative current PDPs, where the plasma is generated by a dielectric barrier discharge, the configuration adopted by most PDP companies The recent improvements and the remaining research issues are discussed

http://plasmapanel.grid.umich.edu/articles/0022-3727_36_6_201.pdf

Plasma display panels: physics, recent developments and key issues

The conversion of methane to more valuable chemicals is one of the most intensively studied topics in catalysis. The direct conversion of methane is attractive because the process is simple, but unfortunately its products are chemicals that are more reactive than methane. The current status of this research field is discussed with an emphasis on C–H bond activation and future challenges.

Methane activation: the past and future

An indirect electrochemical method, which is very efficient for the degradation of organic pollutants in water, is described. The method, named electro-Fenton, is based on electrocatalytical generation of Fenton's reagent to produce hydroxyl radicals, which are very active toward organic compounds. An industrial pollutant, p-nitrophenol (PNP), was chosen for this study and was eventually mineralized. The major intermediary degradation products such as hydroquinone, benzoquinone, 4-nitrocatechol, 1,2,4-trihydroxybenzene and 3,4,5-trihydroxy- nitrobenzene were unequivocally identified by HPLC and GC-MS methods. The rate constants of the hydroxylation reactions were determined. The mineralization of the initial pollutant and the intermediates formed during electro-Fenton treatment was followed by total organic carbon (TOC) analyses. Dependence of mineralization on the amount of electrical energy consumed is shown by the relative decrease of TOC values. A mineralization reaction mechanism is proposed.

Complete Destruction of p-Nitrophenol in Aqueous Medium by Electro-Fenton Method

[1] In the context of recent observations, microphysical models, and laboratory data, a photochemical model of Titan’s atmosphere, including updated chemistry focusing on rate coefficients and cross sections measured under appropriate conditions, has been developed to increase understanding of these processes and improve upon previous Titan photochemical models. The model employs a two-stream discrete ordinates method to characterize the transfer of solar radiation, and the effects of electron-impact, cosmic-ray deposition, and aerosol opacities from fractal and Mie particles are analyzed. Sensitivity studies demonstrate that an eddy diffusion profile with a homopause level of 850 km and a methane stratospheric mole fraction of 2.2% provides the best fit of stratospheric and upper atmosphere observations and an improved fit over previous Titan photochemical models. Lack of fits for C3H8 ,H C3N, and possibly C2H3CN can be resolved with adjustments in aerosol opacity. The model presents a benzene profile consistent with its detection in Titan’s stratosphere [Coustenis et al., 2003], which may play an important role in the formation of Titan hazes. An electron peak concentration of 4200 cm � 3 is

/pdf/current-state-of-modeling-the-photochemistry-of-titan-s-49aa9vsqnk.pdf

Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere

A theoretical framework is presented to describe the possible correlation between the translational and rotational motion of a molecular photofragment, and to relate this to experimental observables The correlation is defined by the values of a number of bipolar moments of the translational and rotational angular distributions which reflect the dynamics of the dissociation process Detailed equations are presented for the polarization dependence of the profiles of recoil Doppler–broadened spectral lines of the photoproduct for two distinct classes of system: (i) molecular photodissociation, followed by spontaneous fluorescence by a molecular product with dispersion of its emission spectrum, and (ii) LIF excitation of a photoproduct, with or without dispersion of the resulting emission The application of the theory is illustrated by calculating the line profiles for two model systems, each with several excitation–detection geometries It is pointed out that there may still be detectable correlation between the product motions even for weakly predissociated parent molecule transitions in which the memory of the initial excitation is lost through extensive rotation before dissociation

The determination of the vector correlation between photofragment rotational and translational motions from the analysis of Doppler‐broadened spectral line profiles

Interaction of vacuum ultraviolet photons with molecules. Formation and dissociation dynamics of molecular superexcited states

Photoabsorption, photoionization, and neutral-dissociation cross sections of simple hydrocarbons in the vacuum ultraviolet range

Doppler profile measurements of balmer-α radiation by electron impact on H2

The Doppler profiles of the Balmer-α emission by electron impact have been investigated through varying the electron energy by using an etalon-grating monochromator with a high-resolving power. In the cases of H 2 and D 2 , the spectral profiles of the Balmer-α emission consist of only one narrow component at an electron energy below 25 eV and another broad component appears above 30 eV, which indicates that there are two kinds of precursors leading to H * (3) or D * (3) responsible for the observed Balmer-α emission. The average energies of H * (3) have the same values as those of D * (3); that is, 0.2 eV and 6.7 eV for the above two components, respectively. In the case of hydrocarbons, the spectral profiles have no structure at any electron energy and the widths of the spectra increase with an increase in the electron energy. Especially for CH 4 , this trend is explained by comparing the above results with that on H * (high Rydberg) produced from CH 4 by electron impact.

The electron energy dependence of the doppler profiles of the Balmer-α emission from H2, D2, CH4 and other simple hydrocarbons by electron impact

The photoabsorption cross sections of C2H6O isomers (ethyl alcohol and dimethyl ether) and C3H8O isomers (n‐propyl alcohol, isopropyl alcohol, and ethyl methyl ether) have been measured in the wavelength region from 30 nm to the ionization potential of each molecule (about 120–130 nm) using an ionization chamber. The obtained photoabsorption cross sections show a maximum value at about 70–80 nm for each molecule. In the wavelength region shorter than about 50 nm, the cross sections are almost the same among isomers and equal to the sum of the cross sections for the constituent atoms. In the longer wavelength region, however, the cross sections show different peaks and shoulders depending on its molecular structure. Especially in the cases of dimethyl ether and ethyl methyl ether vibrational structures of the cross section are observed in the wavelength region from 70 to 100 nm.

Yoshihiko Hatano

Papers

Interaction of vacuum ultraviolet photons with molecules. Formation and dissociation dynamics of molecular superexcited states

Photoabsorption, photoionization, and neutral-dissociation cross sections of simple hydrocarbons in the vacuum ultraviolet range

Doppler profile measurements of balmer-α radiation by electron impact on H2

The electron energy dependence of the doppler profiles of the Balmer-α emission from H2, D2, CH4 and other simple hydrocarbons by electron impact

VUV‐optical oscillator strength distributions of C3H6 and C4H8 isomers