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Title: Photoinduced nucleation: A novel tool for detecting molecules in air at ultra-low concentrations

Abstract

This paper describes the development of a novel detection method and the demonstration of its capability to detect substances at concentrations as small as a few parts per trillion. It is shown that photoinduced nucleation is not in itself a nucleation process; rather, supersaturated vapor condenses onto long-lasting clusters formed by chemical reaction of photo-excited molecules. The role of the supersaturated vapor is to increase the size of these photoproducts by condensation to a size readily detectable by light scattering. Furthermore, the measured nucleation rate variation with illumination wavelength exactly matches the substance's vapor-phase UV light absorption wavelength dependence, thus providing species identification. The ability to detect and identify molecules of substances at extremely low concentrations from ambient air is useful for detecting and monitoring pollutants, and for detecting explosives such as TNT. (c) 2000 American Institute of Physics.

Authors:
 [1];  [1];  [1];  [1]
  1. Department of Chemical Engineering, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)
Publication Date:
OSTI Identifier:
20216294
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 112; Journal Issue: 19; Other Information: PBD: 15 May 2000; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 74 ATOMIC AND MOLECULAR PHYSICS; NUCLEATION; PHOTOCHEMICAL REACTIONS; VAPOR CONDENSATION; MOLECULES; DETECTION; ULTRAVIOLET RADIATION; MEASURING METHODS; EXPLOSIVES; POLLUTANTS; EXPERIMENTAL DATA

Citation Formats

Katz, Joseph L., Lihavainen, Heikki, Rudek, Markus M., and Salter, Brian C. Photoinduced nucleation: A novel tool for detecting molecules in air at ultra-low concentrations. United States: N. p., 2000. Web. doi:10.1063/1.481441.
Katz, Joseph L., Lihavainen, Heikki, Rudek, Markus M., & Salter, Brian C. Photoinduced nucleation: A novel tool for detecting molecules in air at ultra-low concentrations. United States. doi:10.1063/1.481441.
Katz, Joseph L., Lihavainen, Heikki, Rudek, Markus M., and Salter, Brian C. Mon . "Photoinduced nucleation: A novel tool for detecting molecules in air at ultra-low concentrations". United States. doi:10.1063/1.481441.
@article{osti_20216294,
title = {Photoinduced nucleation: A novel tool for detecting molecules in air at ultra-low concentrations},
author = {Katz, Joseph L. and Lihavainen, Heikki and Rudek, Markus M. and Salter, Brian C.},
abstractNote = {This paper describes the development of a novel detection method and the demonstration of its capability to detect substances at concentrations as small as a few parts per trillion. It is shown that photoinduced nucleation is not in itself a nucleation process; rather, supersaturated vapor condenses onto long-lasting clusters formed by chemical reaction of photo-excited molecules. The role of the supersaturated vapor is to increase the size of these photoproducts by condensation to a size readily detectable by light scattering. Furthermore, the measured nucleation rate variation with illumination wavelength exactly matches the substance's vapor-phase UV light absorption wavelength dependence, thus providing species identification. The ability to detect and identify molecules of substances at extremely low concentrations from ambient air is useful for detecting and monitoring pollutants, and for detecting explosives such as TNT. (c) 2000 American Institute of Physics.},
doi = {10.1063/1.481441},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 19,
volume = 112,
place = {United States},
year = {2000},
month = {5}
}