Kinetic Processes in Nitrogen

book

English

The work presents the results obtained during the spectroscopic observations of DC and microwave post-discharges of the pure nitrogen plasmas and nitrogen plasmas containing traces of hydrocarbons and halogenated hydrocarbons. The plasmas have been studied by the emission spectroscopy of three nitrogen and two CN spectral systems. The N2 (B 3Pi_g), N2 (C 3Pi_u) and N2+ (B 2Sigma_u+) vibrational distributions have been studied as a function of decay time at wall temperatures in the interval of 77 - 300 K in the pure nitrogen DC afterglow. The quenching of the nitrogen pink afterglow by the hydrocarbon traces was directly studied and it was shown that the maximum of the pink afterglow intensity is decreasing proportionally to the increase of the methane concentration. The position of the maximum emission is also linearly shifted to the later decay times. The vibrational distributions of N2 (B 3Pi_g) and CN (A 2Pi)) states have been studied as a function of the methane concentration at six selected decay times at wall temperatures of 77 K and 300 K. The influence of hydrocarbon presence on the other observed spectral systems was studied at the same experimental conditions through the selected band, only, due to the strong overlapping of these systems. The strong CN violet system emission was measured at higher hydrocarbon concentrations, especially at 77 K wall temperature. Due to the very high sensitivity to the methane presence a new method of hydrocarbon traces detection in pure nitrogen was proposed and further developed. For its application in determination of the polymer material destruction the influence of various partially or fully halogenated hydrocarbons was verified. The detection limit of this method is about 0.05 ppm of carbon atoms in the pure nitrogen. The direct measurements of the destruction of polyethylene and polypropylene samples were presented. On the base of the experimental results, the appropriate kinetic model of the plasma excited in pure nitrogen and in nitrogen with carbon containing traces was designed. The specific state-to-state energy transfer reactions among the studied states are presented.

Afterglow, atomic recombination, CN spectra emission, collisional excitation energy transfer, DC discharge, decaying plasma, halogenated hydrocarbons, hydrocarbon traces, kinetic processes, liquid nitrogen temperature, low-temperature plasmas, microwave discharge, molecular nitrogen, nitrogen pink afterglow, nitrogen spectra emission, optical emission spectroscopy, polymers disintegration, post-discharge, pure nitrogen, quenching, step-vise ionization

Krčma, F.

2004

10. 1. 2004

VUTIUM

Brno

80-214-2572-5

1

1

1213-418X

Vědecké spisy Vysokého učení technického v Brně Edice Habilitační a inaugurační spisy

132

Czech Republic

1

40

40