Journal ArticleDOI
The limits of signal averaging in atmospheric trace-gas monitoring by tunable diode-laser absorption spectroscopy (TDLAS)
Peter Werle,R. Mücke,F. Slemr +2 more
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In this paper, the concept of the Allan variance is utilized to analyze the stability of an existing frequency-modulated (FM) TDLAS instrument leading to a detection limit for NO2 of 34 pptv at 6 Hz detection bandwidth.Abstract:
Modern research in atmospheric chemistry requires highly sensitive techniques for the measurement of concentrations of free radicals which determine the rate of photochemical destruction of most atmospheric pollutants. Tunable diode-laser absorption spectroscopy (TDLAS) has already been successfully used for measurements of very low concentrations of stable gases, but further improvement in its sensitivity by signal averaging has been limited by the stability of the instrument. In this paper the concept of the Allan variance is utilized to analyze the stability of an existing frequency-modulated (FM) TDLAS instrument leading to a detection limit for NO2 of 34 pptv at 6 Hz detection bandwidth. The stability of the instrument allows averaging over 60 s. Taking into account the measuring cycle consisting of the determination of the sample spectra and zero air spectra as well as gas exchange in the absorption cell, the detection limit achievable with this particular instrument was 10 pptv within 25 s under laboratory conditions. Possibilities of further improvement of the detection limit are discussed.read more
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Journal ArticleDOI
Optical gas sensing: a review
Jane Hodgkinson,Ralph P. Tatam +1 more
TL;DR: In this article, the authors present the basis for each technique, recent developments in methods and performance limitations, and present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.
Journal ArticleDOI
An Aerosol Chemical Speciation Monitor (ACSM) for Routine Monitoring of the Composition and Mass Concentrations of Ambient Aerosol
Nga L. Ng,Scott C. Herndon,A. Trimborn,Manjula R. Canagaratna,Philip Croteau,Timothy B. Onasch,Donna Sueper,D. R. Worsnop,Qi Zhang,Yele Sun,J. T. Jayne +10 more
TL;DR: The Aerosol Chemical Speciation Monitor (ACSM) as mentioned in this paper uses an aerodynamic particle focusing lens combined with high vacuum thermal particle vaporization, electron impact ionization, and mass spectrometry.
Journal ArticleDOI
Near- and mid-infrared laser-optical sensors for gas analysis
TL;DR: In this paper, the authors reviewed the current available semiconductor laser sources for spectroscopy in the near and mid-infrared spectral region based upon gallium arsenide, indium phosphite, antimonides and lead-salt containing compounds.
Journal ArticleDOI
A review of recent advances in semiconductor laser based gas monitors
TL;DR: In this paper, the main features and applications of tunable diode laser absorption spectroscopy are reviewed and the main characteristics of the currently available semiconductor diode lasers with respect to spectroscopic applications and sensitive detection techniques are discussed.
Book ChapterDOI
Mid-Infrared Laser Applications in Spectroscopy
TL;DR: In this paper, the authors discuss recent developments of mid-infrared laser sources, with emphasis on established and new spectroscopic techniques and their applications for sensitive, selective, and quantitative trace gas detection.
References
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Statistics of atomic frequency standards
TL;DR: In this paper, a theoretical analysis of the relationship between the expectation value of the standard deviation of the frequency fluctuations for any finite number of data samples and the infinite time average value of a standard deviation is presented.
Book
Statistical Methods for Environmental Pollution Monitoring
TL;DR: In this paper, the authors proposed three-stage sampling: simple random sampling, two stage sampling and three stage sampling, and two-stage and double sampling, respectively, to estimate the mean and variance from censored data sets.
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Taschenbuch der Mathematik
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TL;DR: This paper presents a meta-analyses of the statistical methods used to estimate the Boltzmann inequality, a measure of the uncertainty in the solutions to the inequality of the discrete-time equations.
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Chemistry of the natural atmosphere
TL;DR: In this paper, the authors present the bulk composition, structure, and dynamics of the atmosphere and discuss the chemistry of the Troposphere: the Methane Oxidation Cycle, ozone, and sulfur compounds.
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TL;DR: The field of atmospheric chemistry is very broad, both in the problems addressed and in the approaches taken, and addresses chemistry from the lower to the upper atmosphere, in remote and polluted regions, from marine to continental areas, and both outdoors and indoors.
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