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Use of ion‐energy distributions for the identification of species and production mechanisms in low‐pressure DC discharges
Author(s) -
Herrero Víctor J.,
Islyaikin Andrey M.,
Tanarro Isabel
Publication year - 2008
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1388
Subject(s) - humanities , physics , art
3 pages, 2 figures.-- Printed version published Aug 2008.-- Published in section JMS Letters.Mass spectrometry finds widespread application in the analysis of ion distributions in different kinds of plasmas. In DC discharges,\udthe ions reaching the cathode are usually collected by means of a sampling orifice and focused with a set of electrostatic lenses onto\udthe entrance of a mass filter. Mass spectra of ions coming directly from the plasma are not affected by the fragmentation problems at the detector that plague the mass spectrometry of neutrals, but the recorded mass distributions are not entirely free from ambiguity. In particular, ions with the same mass/charge (m/q) ratio, but with different chemical composition, will contribute to the same peak. This can be a problem especially for discharges in gas mixtures that can lead to a variety of different products. Additional insight can be derived from the measurement of ion-energy distributions. These energy distributions are largely determined by the acceleration of the ions in the sheath region between the plasma and the cathode, but they may also carry specific information about ion generation mechanisms within the plasma or about collisional processes in the sheath, which can in turn be of help for the identification of different ions with the same m/q ratio.This work has been funded by the DGI (MEC) of Spain under grants ENE 2006-14577 and FIS 2007-61686.Peer reviewe