Quantitative Fourier Transform Infrared Diagnostics of the Gas-Phase Composition Using the HITRAN Database and the Equivalent Width of the Spectral Features

Sepman, AV Alexey; Blanken, den R; Schepers, R; Goey, de Lph Philip

doi:10.1366/000370209789806948

Cited by 12 publications

(11 citation statements)

References 14 publications

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“…The ILS must be consistent with the actual parameters of the spectrometer used. Integral absorption [22] is a method which simplifies the analysis of complex spectra where ILS is not known exactly.…”

Section: The Methods Proposed For the Determination Of Gas Concentratimentioning

confidence: 99%

A Multi-Band Integrated Virtual Calibration-Inversion Method for Open Path FTIR Spectrometry

Cięszczyk¹

2013

Metrology and Measurement Systems

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This paper addresses problems arising from in situ measurement of gas content and temperature. Such measurements can be considered indirect. Transmittance or natural radiation of a gas is measured directly. The latter method (spectral radiation measurement) is often called spectral remote sensing. Its primary uses are in astronomy and in the measurement of atmospheric composition. In industrial processes, in situ spectroscopic measurements in the plant are often made with an open path Fourier Transform Infrared (FTIR) spectrometer. The main difficulty in this approach is related to the calibration process, which often cannot be carried out in the manner used in the laboratory. Spectral information can be obtained from open path spectroscopic measurements using mathematical modeling, and by solving the inverse problem. Determination of gas content based on spectral measurements requires comparison of the measured and modeled spectra. This paper proposes a method for the simultaneous use of multiple lines to determine the gas content. The integrated absorptions of many spectral lines permits calculation of the average band absorption. An inverse model based on neural networks is used to determine gas content based on mid-infrared spectra at variable temperatures.

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Section: The Methods Proposed For the Determination Of Gas Concentratimentioning

confidence: 99%

A Multi-Band Integrated Virtual Calibration-Inversion Method for Open Path FTIR Spectrometry

Cięszczyk¹

2013

Metrology and Measurement Systems

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“…In calculation, the integrated absorption of individual rotational lines of finite extent at lower resolutions should be considered. However, if the integration width is greater than 3 cm -1 , the error resulting from the ILS width is less than 1% [38]. Figures 4 and 5 show the ranges of the spectrum for which absorption was integrated.…”

Section: Modeling Of Gas Spectramentioning

confidence: 99%

“…Figures 4 and 5 show the ranges of the spectrum for which absorption was integrated. The individual ranges correspond to the CO rotational lines, similarly as in [38]. …”

Section: Modeling Of Gas Spectramentioning

confidence: 99%

A Local Model and Calibration Set Ensemble Strategy for Open-Path FTIR Gas Measurement with Varying Temperature

Cięszczyk¹

2013

Metrology and Measurement Systems

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Open-Path Fourier Transform Infrared OP-FTIR spectrometers are commonly used for the measurement of atmospheric pollutants and of gases in industrial processes. Spectral interpretation for the determination of gas concentrations is based on the HITRAN database line-by-line modeling method. This article describes algorithms used to model gas spectra and to determine gas concentration under variable temperatures. Integration of individual rotational lines has been used to reduce the impact of spectrometer functions on the comparison of both measured and synthetic modeled spectra. Carbon monoxide was used as an example. A new algorithm for gas concentration retrieval consisting of two ensemble methods is proposed. The first method uses an ensemble of local models based on linear and non-linear PLS (partial least square) regression algorithms, while the second is an ensemble of a calibration set built for different temperatures. It is possible to combine these methods to decrease the number of regression models in the first ensemble. These individual models are appropriate for specific measurement conditions specified by the ensemble of the calibration set. Model selection is based on comparison of gas spectra with values determined from each local model.

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“…Additionally, it has many potential benefits such as fast analysis and update rate, no carrier gas requirement, less susceptible to cogging, etc., and is called the best way toward green analytical chemistry [7]. But on the other contrary, although a spectrum is relatively easy to measure, converting spectrum to absolute concentration values is difficult because the measured spectrum is the convolution of the transmission spectrum and the FTIR apparatus function [8], which make some absorbances nonlinear to gas concentration. When there are several analytes whose absorption spectra overlap extensively, the difficulty may arise greatly.…”

Section: Introductionmentioning

confidence: 99%

On-line multi-component alkane mixture quantitative analysis using Fourier transform infrared spectrometer

Tang

Zhu

et al. 2015

Chemometrics and Intelligent Laboratory Systems

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Keywords:FTIR Multi-component alkane mixture On-line quantitative analysis Feature extraction and selection Calibration transfer Fourier transform infrared spectrometer (FTIR) has been widely used to analyze multi-component gas mixture for more than ten years because of its potential benefits. However, it is a challenge to analyze multicomponent alkane mixture on-line with FTIR because their absorption spectra overlap with each other extensively. In this paper, the methods of feature extraction and selection based on Tikhonov regularization (TR), and the modeling methods based on neural network (NN) are discussed in the practical conditions of alkane mixture analysis with FTIR. Then, the proposed methods compared with gas chromatograph (GC), normally regarded as the standard way for quantitative gas analysis, are used for gas well logging to analyze the mixture of methane, ethane, propane, iso-butane and n-butane on-line. By comparing the well logging curves obtained from FTIR with the ones from GC, it is shown that the logging curves analyzed with proposed method are good matches with the ones obtained from GC, which means that our analysis results are accurate. At the end of this paper, a calibration transfer is used to calibrate additional 18 instruments with a few sets of samples. And the work introduced in this paper demonstrates that FTIR can also be used in analyzing multi-component gas with close molecular structure accurately and the analyzer can be produced in mass.

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Quantitative Fourier Transform Infrared Diagnostics of the Gas-Phase Composition Using the HITRAN Database and the Equivalent Width of the Spectral Features

Cited by 12 publications

References 14 publications

A Multi-Band Integrated Virtual Calibration-Inversion Method for Open Path FTIR Spectrometry

A Multi-Band Integrated Virtual Calibration-Inversion Method for Open Path FTIR Spectrometry

A Local Model and Calibration Set Ensemble Strategy for Open-Path FTIR Gas Measurement with Varying Temperature

On-line multi-component alkane mixture quantitative analysis using Fourier transform infrared spectrometer

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