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Atmospheric helium capillary dielectric barrier discharge for soft ionization: Determination of atom number densities in the lowest excited and metastable states.
MedLine Citation:
PMID:  24320177     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The populations of the lowest excited helium states 2s 3S1, 2s 1S, 2p 3P0J and 2p 1P0 created in an atmospheric helium capillary dielectric barrier discharge were determined by means of optical emission spectroscopy. The emitted intensities of 388, 501, 587 and 667 nm lines were measured side-on and end-on with respect to the discharge axis. The comparison of optically thin side-on spectra with end-on spectra, which exhibited the absorption effects in the line kernels, enabled the determination of the average values of the number densities n1 in the considered He states along the plasma length L. The field of the theoretical profiles for a series of the n1L parameters pertinent to the experimental conditions was calculated for each line. By introducing the experimental data into the field of calculated curves, n1L corresponding to the particular state could be obtained. The measurements of the emission profiles were done as a function of the discharge voltage in the range covering homogeneous as well as filamentary DBD operation mode. Due to non-uniformity of the excited atom density distribution along the plasma, the values of n1 could be obtained only in the homogeneous operation mode where the non-uniformity was small. The following maximum values were found for the number densities in the investigated states: (2s 3S1) = (2.9  1.1)1013 cm-3, (2s 1S) = (1.4  0.5)1013 cm-3, (2p 3P0J) = (1.1  0.4)1013 cm-3, (2p 1P0) = (4.2  1.6)1012 cm-3, and they represent the average populations along the plasma column in the capillary.
Authors:
Vlasta Horvatic; Saskia Müller; Damir Veza; Cedomil Vadla; Joachim Franzke
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-12-10
Journal Detail:
Title:  Analytical chemistry     Volume:  -     ISSN:  1520-6882     ISO Abbreviation:  Anal. Chem.     Publication Date:  2013 Dec 
Date Detail:
Created Date:  2013-12-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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