Discrete sums for the rapid determination of exponential decay constants

Everest, Michael A.; Atkinson, Dean B.

doi:10.1063/1.2839918

Cited by 63 publications

(54 citation statements)

References 26 publications

(24 reference statements)

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“…The digitized signal was transferred to a personal computer for exponential fitting with the Linear Regression of the Sum (LRS) algorithm (Halmer et al 2004) in a custom LabVIEW program. The LRS algorithm was selected because of its computational efficiency and reported noise immunity (Everest and Atkinson 2008). Multi-exponential decay originating from off-axis alignment was evident in the FFT of the decay transient (Lee et al 2002) and was minimized during cavity alignment.…”

Section: Crd Apparatusmentioning

confidence: 99%

A Calibration Technique for Improving Refractive Index Retrieval from Aerosol Cavity Ring-Down Spectroscopy

Toole¹,

Renbaum-Wolff

Smith³

2013

Aerosol Science and Technology

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Cavity ring-down spectroscopy (CRDS) is a technique that is commonly used to measure the extinction of light by aerosol particles in situ. This extinction, when normalized to particle concentration, yields the extinction cross section, a measure of a single particle's ability to scatter and absorb light. The complex index of refraction can then be retrieved by comparison of the extinction cross sections at several particle diameters with those predicted by Mie theory. This approach requires accurate determination of particle diameter and concentration as well as the length of the extinction region in the cavity, but it is often difficult to quantify the systematic errors in the measurements of these quantities. Here, we introduce a calibration technique using particles of a reference compound to account for these systematic errors. The two calibration parameters are: C f , which scales the measured extinction cross sections, and d, which shifts the particle diameters. It is found that C f correlates strongly with the condensation particle counter (CPC) used to measure particle concentration and that d is associated with the differential mobility analyzer (DMA) used to select particle diameters. Calibration is shown to reduce errors of subsequently-measured extinction cross sections of a test aerosol from 11% to <2% with a concomitant improvement in the accuracy of the retrieved complex index of refraction and corresponding atmospheric radiative forcing estimates.

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Section: Crd Apparatusmentioning

confidence: 99%

A Calibration Technique for Improving Refractive Index Retrieval from Aerosol Cavity Ring-Down Spectroscopy

Toole¹,

Renbaum-Wolff

Smith³

2013

Aerosol Science and Technology

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“…the sum" (LRS) algorithm (Everest and Atkinson, 2008;Taha et al, 2013) and at a diode laser pulse repetition rate of 1 kHz.…”

Section: Thermal Dissociation Cavity Ring-down Spectroscopymentioning

confidence: 99%

A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

et al. 2014

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Abstract. The peroxycarboxylic nitric anhydrides (PANs, molecular formula: RC(O)O 2 NO 2 ) can readily be observed by gas chromatography (PAN-GC) coupled to electron capture detection. Calibration of a PAN-GC remains a challenge, because the response factors differ for each of the PANs, and because their synthesis in sufficiently high purity is non-trivial, in particular for PANs containing unsaturated side chains. In this manuscript, a PAN-GC and its calibration using diffusion standards, whose output was quantified by blue diode laser thermal dissociation cavity ringdown spectroscopy (TD-CRDS), are described. The PAN-GC peak areas correlated linearly with total peroxy nitrate ( PN) mixing ratios measured by TD-CRDS (r > 0.96). Accurate determination of response factors required the concentrations of PAN impurities in the synthetic standards to be subtracted from PN. The PAN-GC and its TD-CRDS calibration method were deployed during ambient air measurement campaigns in Abbotsford, BC, from 20 July to 5 August 2012, and during the Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS) campaign at the AMS13 ground site in Fort McKay, AB, from 10 August to 5 September 2013. The PAN-GC limits of detection for PAN, PPN, and MPAN during FOSSILS were 1, 2, and 3 pptv, respectively. For the Abbotsford data set, the PAN-GC mixing ratios were compared, and agreed with those determined in parallel by thermal dissociation chemical ionization mass spectrometry (TD-CIMS). Advantages and disadvantages of the PAN measurement techniques used in this work and the utility of TD-CRDS as a PAN-GC calibration method are discussed.

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“…The DAQ program also performs real-time analysis of the ringdown data. Individual ringdown traces are analyzed using a high-speed exponential fitting routine (Everest and Atkinson 2008). At typical laser repetition rates of 1 kHz, 1000 decay traces are acquired and analyzed per channel per second with no co-adding.…”

Section: Data Acquisition (Daq) and Analysismentioning

confidence: 99%

Aircraft Instrument for Comprehensive Characterization of Aerosol Optical Properties, Part I: Wavelength-Dependent Optical Extinction and Its Relative Humidity Dependence Measured Using Cavity Ringdown Spectroscopy

Langridge

Richardson

Lack

et al. 2011

Aerosol Science and Technology

103

117

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High-quality in situ observations of aerosol particle optical properties, namely extinction, scattering, and absorption, provide important information needed to constrain the role of aerosols in the climate system. This paper outlines the design and performance of an aircraft instrument utilizing cavity ringdown spectroscopy for the measurement of aerosol extinction. The 8-channel cavity ringdown spectrometer measures extinction at multiple wavelengths (405, 532, and 662 nm) and at multiple relative humidities (e.g., 10%, 70%, and 95%). Key performance characteristics include a 1-s detection limit better than 0.1 Mm −1 , accuracy of <2% for dry aerosol measurements, and a 1-s precision better than 40% for extinction levels of >10 Mm −1 . Laboratory and field data demonstrate that the 1-s precision is limited by the statistics of aerosol particles in the laser beam rather than the precision of the extinction measurement per se. The measurement precision improves with averaging to 5% at 60 s for extinction levels of >10 Mm

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Discrete sums for the rapid determination of exponential decay constants

Cited by 63 publications

References 26 publications

A Calibration Technique for Improving Refractive Index Retrieval from Aerosol Cavity Ring-Down Spectroscopy

A Calibration Technique for Improving Refractive Index Retrieval from Aerosol Cavity Ring-Down Spectroscopy

A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

Aircraft Instrument for Comprehensive Characterization of Aerosol Optical Properties, Part I: Wavelength-Dependent Optical Extinction and Its Relative Humidity Dependence Measured Using Cavity Ringdown Spectroscopy

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