In:
Applied Spectroscopy, SAGE Publications, Vol. 58, No. 9 ( 2004-09), p. 1038-1043
Abstract:
We have developed a miniature fiber-optic probe with no focusing optics for in situ analysis of volatile organic compounds (VOCs). The probe uses an optical fiber to transmit a laser pulse to a vapor sample causing it to ionize adjacent to the fiber tip through a resonance-enhanced multiphoton ionization (REMPI) process. The distal end of the optical fiber is contained co-axially within 2-mm-inner-diameter stainless steel tubing that serves as an electrode. The electrode is biased at a high positive potential to collect electrons. The current generated is shown to be proportional over about two orders of magnitude to the concentration of the species ionized. Visible wavelength REMPI spectroscopy is used to determine probe sensitivities of 20 ppb (benzene) and 43 ppb (toluene). Designing the probe without focusing optics specifies an achromatic ionization region constant in size and position as the laser wavelength is scanned, which simplifies data collection and reduction. Focusing achromatic systems are discussed and the potential signal improvement is estimated.
Type of Medium:
Online Resource
ISSN:
0003-7028
,
1943-3530
DOI:
10.1366/0003702041959479
Language:
English
Publisher:
SAGE Publications
Publication Date:
2004
detail.hit.zdb_id:
1474251-2
SSG:
11
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