Application of excitation cross sections to optical plasma diagnostics

Abstract

Many optical-based plasma diagnostic techniques require electron-impact excitation cross sections. In recent years, a considerable number of new results have become available for excitation of rare-gas atoms from both the ground state and metastable states. Using relatively simple techniques these cross sections can be combined with plasma emission measurements to extract many useful plasma parameters such as the electron temperature. Many of the limitations of simple plasma emission models such as the corona model can be overcome by using cross section measurements to select what particular emission lines to use in the analysis.

Experimental and Numerical Investigations of Line-Shaped Microwave Argon Plasma Source

“…For further increase of pressure above 20 Torr, the emission intensity was relatively flat. The increment of the emission intensity of red line in the pressure range 1-5 Torr can be attributed to the presence of Ar (1s) metastable and the resulting electron impact step-wise excitation [17]. Meanwhile, the increase of argon pressure beyond 5 Torr causes more electron energy loss, hence decrease in metastable Ar density and, consequently, emission intensity of "red" lines decreases in the pressure range 5-20 Torr.…”

Measurement of Argon emission spectral of ICP plasma using a diagnostic system based on photomultiplier tubes array

“…In our ICP rf Argon discharge process, the pressure is 20mTorr and the flow is 200sccm, hence the corona model is valid for analyzing the process. The reason is that other collisional processes are trivial and the density of metastables is too low to make a significant contribution to the excitation of the excited species under these conditions [9][10][11]. In a corona model for these levels, we have the electron-impact excitation from the ground-state atom, Ar(gs) + e Ar(2p1 ) + e (1) and the spontaneous radiation, Ar(2p 1 )Ar(1s 2 ) + hv…”

Optical and Electron Spectrometry of Molecules of Biological Interest

“…Optical Materials, ISCOM07, Belgrade, Serbia, September [3][4][5][6][7]2007 Optical and Electron Spectrometry of Molecules of Biological Interest Optical absorption and emission spectroscopy together with low energy electron interaction (elastic scattering, excitation, ionization, resonances) with biologically relevant molecules (nitrogen, oxygen, water, alcohols, tetrahydrofuran, tetrahydrofurfuril alcohol, 3-hydroxytetrahydrofuran, pyrimidine, glycine, alanine) are studied in order to understand radiation damage and to investigate the presence of pollutants in the atmosphere. Versatile high resolution electron spectrometers are used in the present study of electron-molecule interactions.…”

“…Besides gaining the fundamental knowledge of interactions between projectile particle (photon/electron) and molecules, better understanding of fundamental processes is needed in areas of investigation like environmental studies [1], radiation damage of DNA and other cellular components [2], optical plasma diagnostics [3], etc. Also, there are recent results that indicate that both UV and electron radiation of ice mixtures of organic molecules (a gas mixture deposited on a cold surface at about 10 K) can lead to the formation of the simplest amino acids such as glycine and alanine [4].…”