Fast exponential fitting algorithm for real-time instrumental use

Halmer, Daniel; Basum, Golo von; Hering, P.; Mürtz, Manfred

doi:10.1063/1.1711189

Cited by 86 publications

(43 citation statements)

References 12 publications

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“…A UG11 filter was placed between the rear mirror of the ring-down cavity and the PMT to suppress the flame chemiluminescence. The signal was recorded using the digital scope triggered on the laser pulse, averaged over 255 pulses and processed in order to measure the cavity decay time, s(k), using a fast exponential fitting algorithm for real-time instrumentation [33] with Labview 7.1. The fitting procedure was performed over 920 points, which represents a duration of 1840 ns (i.e., around 4 Â s(k)), with a resulting standard deviation lower than 0.2%.…”

Section: Laser Diagnosticsmentioning

confidence: 99%

Experimental and numerical study of the role of NCN in prompt-NO formation in low-pressure CH4–O2–N2 and C2H2–O2–N2 flames

Lamoureux

Desgroux

Bakali

et al. 2010

Combustion and Flame

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Section: Laser Diagnosticsmentioning

confidence: 99%

Experimental and numerical study of the role of NCN in prompt-NO formation in low-pressure CH4–O2–N2 and C2H2–O2–N2 flames

Lamoureux

Desgroux

Bakali

et al. 2010

Combustion and Flame

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“…As many as 100 ring-down traces of τ ≈ 26 μs were acquired using a fast fitting algorithm 52 at a rate of 20 Hz-30 Hz and averaged at each wavelength, corresponding to a minimum detectable absorption coefficient of ≈4 × 10 −10 cm −1 (see Fig. 1(b)).…”

Section: Methodsmentioning

confidence: 99%

Observations of Dicke narrowing and speed dependence in air-broadened CO2 lineshapes near 2.06 μm

Bui

Long

Cygan

et al. 2014

The Journal of Chemical Physics

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The line shape problem in the near-infrared spectrum of self-colliding CO 2 molecules: Experimental investigation and test of semiclassical models J. Chem. Phys. 130, 184306 (2009) Frequency-stabilized cavity ring-down spectroscopy was used to study CO 2 lineshapes in the (20013) ← (00001) band centered near 2.06 μm. Two rovibrational transitions were chosen for this study to measure non-Voigt collisional effects for air-broadened lines over the pressure range of 7 kPa-28 kPa. Lineshape analysis for both lines revealed evidence of simultaneous Dicke (collisional) narrowing and speed-dependent effects that would introduce biases exceeding 2% in the retrieved air-broadening parameters if not incorporated in the modeling of CO 2 lineshapes. Additionally, correlations between velocity-and phase/state changing collisions greatly reduced the observed Dicke narrowing effect. As a result, it was concluded that the most appropriate line profile for modeling CO 2 lineshapes near 2.06 μm was the correlated speed-dependent NelkinGhatak profile, which includes all of the physical effects mentioned above and leads to a consistent set of line shape parameters that are linear with gas pressure. © 2014 AIP Publishing LLC.

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“…Ten decay transients were sampled at 200 MSa/s (megasamples per second) and averaged on the oscilloscope (HP 5483, 600 MHz, 50 termination, 8 bit ADC). 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).…”

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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Fast exponential fitting algorithm for real-time instrumental use

Cited by 86 publications

References 12 publications

Experimental and numerical study of the role of NCN in prompt-NO formation in low-pressure CH4–O2–N2 and C2H2–O2–N2 flames

Experimental and numerical study of the role of NCN in prompt-NO formation in low-pressure CH4–O2–N2 and C2H2–O2–N2 flames

Observations of Dicke narrowing and speed dependence in air-broadened CO2 lineshapes near 2.06 μm

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

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