Metastable State Of N2 Research Articles

Stability and dissociation dynamics of N2 (++) ions following core ionization studied by an Auger-electron-photoion coincidence method.

An Auger-electron-photoion coincidence (AEPICO) method has been applied to study the stability and dissociation dynamics of dicationic states after the N K-shell photoionization of nitrogen molecules. From time-of-flight and kinetic energy analyses of the product ions, we have obtained coincident Auger spectra associated with metastable states of N2 (++) ions and dissociative states leading to N2 (++) → N(+) + N(+) and N(++) + N. To investigate the production of dissociative states, we present two-dimensional AEPICO maps which reveal the correlations between the binding energies of the Auger final states and the ion kinetic energy release. These correlations have been used to determine the dissociation limits of individual Auger final states.

Generation of various radicals in nitrogen plasma and their behavior in media

Research on the generation of radicals in nitrogen plasma shows that the most dominant radicals are excited nitrogen molecules in the metastable state of N2(A3∑u+). Hydroxyl molecules are generated from the dissociation of water molecules upon contact with excited nitrogen molecules. The estimated densities of various radicals in nitrogen plasma with an electron temperature of 1 eV are presented in this study. The behavior of these radicals in media is also investigated. Excited nitrogen molecules in the N2(A3∑u+) state from a plasma jet are injected into water, after which the molecules disappear instantaneously within a few tens of nm, producing hydroxyl molecules. Hydrogen peroxide, hydrogen dioxide, and nitrogen monoxide molecules can diffuse much deeper into water, implying the possibility that a chemical reaction between hydrogen dioxide and nitrogen monoxide molecules produces hydroxyl molecules in deep water, even though density in this case may not be very high.

The quenching effect of hydrogen on the nitrogen in metastable state in atmospheric-pressure N2-H2 microwave plasma torch

The atmospheric-pressure microwave N2-H2 plasma torch is generated and diagnosed by optical emission spectroscopy. It is found that a large amount of N atoms and NH radicals are generated in the plasma torch and the emission intensity of N2+ first negative band is the strongest over the spectra. The mixture of hydrogen in nitrogen plasma torch causes the morphology of the plasma discharge to change with appearance that the afterglow shrinks greatly and the emission intensity of N2+ first negative band decreases with more hydrogen mixed into nitrogen plasma. In atmospheric-pressure microwave-induced plasma torch, the hydrogen imposes a great influence on the characteristics of nitrogen plasma through the quenching effect of the hydrogen on the metastable state of N2.

CN spectroscopy and physico–chemistry in the boundary layer of a C/SiC tile in a low pressure nitrogen/carbon dioxide plasma flow

The boundary layer of a C/SiC tile in a low pressure nitrogen/carbon dioxide plasma flow is investigated by numerous measurement techniques. CN emission is especially studied through its red and violet systems. Radial and axial profiles of CN relative density are obtained and absolute values are estimated by calibration, thanks to a tungsten lamp. Rotational and vibrational temperatures are determined and compared with wall, heavy particle, and electron temperatures. High vibronic bands should be taken into account in order to determine accurate vibrational temperatures. Δv=0 sequence of the violet system is examined in detail and differences between calculations made using existing sets of spectroscopic constants and experimental spectra are pointed out. Inadequacy of very accurate Fourier transform spectroscopy (FTS) sets of constants in high temperature calculations is underlined. CN and NO density increases in the boundary layer are explained through a dissociative adsorption of N2(v) or N2(A 3Σ+). Such a process implies a significant action of nitrogen in surface erosion. Excitation of CN and NO by electrons is rejected and an excitation transfer with vibrationally excited and metastable states of N2 and CO is proposed.

N2(a″ 1Σg+) metastable collisional destruction and rotational excitation transfer by N2

Quenching and rotational coupling rate coefficients have been measured for the J=4–10, v=0 levels of the a″ 1Σg+ metastable state of N2 in collisions with ground state N2. Laser absorption is used to monitor the population of rotational levels of the a″ 1Σg+ state following depletion of the population of one or more levels by optical pumping to other states. The observed time dependence of the recovery of population of the perturbed level and the collision induced growth and decay of the populations of adjacent levels are interpreted in terms of quenching to other electronic levels and excitation exchange among adjacent rotational levels. For the J=6, v=0 level of the a″ 1Σg+ state the rate coefficients extrapolated to zero discharge current at 300 K are 2.3±0.1×10−16 m3/s for electronic quenching and 1.1±0.6×10−16 m3/s for excitation transfer to the J=4 and J=8 levels in collisions with N2. Very similar rate coefficients were obtained for the J=4, 7, and 8 levels.

Electron-Impact Excitation Functions for Metastable States of N2

The metastable excitation function for N2 is mainly due to the A 3Σu+, E 3Σg+, and a 1Πg states. This interpretation, which is based on (1) the optical-excitation functions for these states, (2) their radiative lifetimes, and (3) new measurements of the metastable excitation function at a range of times after excitation, is consistent with other workers' data. The roles of several other metastable states of N2 are also discussed.

Excitation and ionization of Hg by metastable states of N2 and CO

When metastable states of N2 and CO collide with mercury atoms, the excitation energy can be transferred to the mercury atom, yielding a fluorescence in the spectral lines of mercury. This note describes observations of this process using a thermal beam of metastable molecules excited by electron impact. Metastable CO excites only the 63P levels of Hg. Metastable N2 excites predominantly 63P, but some 10% of collisions excite 61P, and higher states are also excited. In addition, ionization of Hg by excited N2 (but not by CO) is reported. Other observations are reported briefly.