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ABSTRACT: The authors measured IR transmission spectra of two different concentrations of bacillus subtilis spores by using Fourier transform infrared spectroscopy (FTIR) technology. The mass extinction cross section k of bacillus subtilis spores was calculated according to Lambert-Beer law and the imaginary part n(i) of the complex refractive index was also calculated through k. The real part n(r) of the complex refractive index was derived from the KK (Kramers-Kronig) relationship and the experimental results were also analyzed and discussed with the study of measurement and analysis method of the complex refractive index on bacillus subtilis spores, it is of great significance to further research the absorption and scattering characteristics, and to broaden the measurement and remote sensing technology method of the biological aerosols.
Guang pu xue yu guang pu fen xi = Guang pu 12/2012; 32(12):3193-6. · 0.84 Impact Factor
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ABSTRACT: Passive remote sensing by Fourier-transform infrared (FTIR) spectrometry allows detection of air pollution. However, for the localization of a leak and a complete assessment of the situation in the case of the release of a hazardous cloud, information about the position and the distribution of a cloud is essential. Therefore, an imaging passive remote sensing system comprising an interferometer, a data acquisition and processing software, scan system, a video system, and a personal computer has been developed. The remote sensing of SF6 was done. The column densities of all directions in which a target compound has been identified may be retrieved by a nonlinear least squares fitting algorithm and algorithm of radiation transfer, and a false color image is displayed. The results were visualized by a video image, overlaid by false color concentration distribution image. The system has a high selectivity, and allows visualization and quantification of pollutant clouds.
Guang pu xue yu guang pu fen xi = Guang pu 07/2012; 32(7):1754-7. · 0.84 Impact Factor
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Sheng Li, Min-guang Gao,
Yu-jun Zhang,
Wen-qing Liu,
Liang Xu,
Jing-jing Tong,
Si-yang Cheng,
Ling Jin,
Xiu-li Wei,
Ya-ping Wang,
Jun Chen
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ABSTRACT: An ozone monitoring system was developed by the method of open path Fourier transform infrared (OP-FTIR) spectrometry based on our FTIR spectrometer. In order to improve measurement precision and detection limit, the quantitative analysis was completed to get ozone concentration by combining synthetic background spectrum method which uses information from HITRAN database and instrumental line shape, and nonlinear least squares (NLLSQ) method. The measurement methods for system detection limit were discussed and the result is 1.42 nmol x mol(-1) with sixteen times averages. The authors developed continuous monitoring experiments in the suburban area of Hefei. For the day and month measurement results, the authors analyzed their variations with the generation sources. The result has shown that this system is reliable and precise and can be used as a new device and method for national ozone monitoring.
Guang pu xue yu guang pu fen xi = Guang pu 12/2011; 31(12):3256-9. · 0.84 Impact Factor
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Si-yang Cheng, Min-guang Gao,
Liang Xu,
Tian-shu Zhang,
Yi-huai Lu,
Jian-guo Liu,
Jing-jing Tong,
Ling Jin,
Sheng Li,
Xiu-li Wei,
Wen-qing Liu
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ABSTRACT: The stratosphere ozone plays the protective action role for human and the ground-level ozone is harmful to human health. Monitoring ozone with different ways and methods took an active part in understanding distribution and transformation of ozone, which was useful to controlling pollution emission. Spectra were got by multi-reflected white cell Fourier transform infrared (FTIR) spectrometer, inversed with nonlinear least squares (NLLSQ) method and then the concentrations of ozone were got exactly. The correlations of measured ozone concentration time series by Fourier transform infrared spectrometer, open path UV differential optical absorption spectrometer and ozone analyzer of the Thermo Corporation were significant. The results showed that the measured ozone absolute concentrations with different monitoring methods and instruments had some differences, but the concentration diurnal variations were coincident and the correlations were good. Therefore, ozone concentration inversion method, based on multi-reflected cell Fourier transform infrared spectrum and not reported in domestic articles, could be used as an effective technique to measure ozone concentration.
Guang pu xue yu guang pu fen xi = Guang pu 05/2011; 31(5):1212-5. · 0.84 Impact Factor
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ABSTRACT: The spectral line widths of theory and experiment are analyzed with different temperatures; the line strengths under room temperature in HITRAN database are corrected to measured temperature, and then synthetic spectra are calculated. With the nonlinear least squares fit between measured spectra and calibration spectra, standard gas concentrations of CO at different temperatures are obtained. The inversion concentration error of this algorithm at room temperature is less than 5% with high precision. But with the temperature increasing, the concentration error will increase gradually. At the same time, there is the same apparent structure to component CO in the residual spectrum. Also, with higher temperature, the structure is more obvious and can not be removed by increasing the number of fitting. Comparing experimental results and theoretical analysis, the temperature correction methods of calibration spectra, which are not suitable for high temperature gas, are the main reason for inversion error at higher temperature. These results have important significance for further research on accurately correcting parameters and how to inverse the high temperature gas concentrations more accurately.
Guang pu xue yu guang pu fen xi = Guang pu 01/2011; 31(1):82-5. · 0.84 Impact Factor
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ABSTRACT: In the present paper, a new method is introduced for real-time monitoring polluted gas emission flux of chemical plant, which is called FTIR based on the solar occultation flux technique (SOF-FTIR). The model to obtain background spectrum, measured spectrum and atmospheric penetration rate surrounding polluted gas under complicated conditions is also proposed. Continuous measurements were preformed at a closed loop surrounding the contaminated areas that need to be mornitored to obtain measured spectrum, and finally column concentration of polluted gas was retrieved by using the nonlinear least squares fitting algorithm (NLLS). Then the flux information combined with the meteorological data and GPS information of the time was obtained when the experiments were done. Using this method, remote sensing experiment of ammonia emission around a chemical plant was done, and the concentration distribution and its emission flux was quantitatively analyzed. Compared with traditional FTIR methods of monitoring, this method is featured by convenient operation and high maneuverability, so it has a good application prospect in pollution monitoring and other applications in regional air pollution contingency monitoring.
Guang pu xue yu guang pu fen xi = Guang pu 06/2010; 30(6):1478-81. · 0.84 Impact Factor
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ABSTRACT: In the present paper, the authors used FTIR spectra measurement to analyze the volatilization of NH3 of different fertilizers. With the help of HITRAN database, using NLLS arithmetic, the authors retrieved the concentrations of NH3. The authors compared the concentrations and simply analyzed the reason why the concentrations are different. This experiment indicated that the FTIR spectra measurement used to analyze the volatilization of NH3 has many advantages, such as simple operation, high efficiency, measuring in real time and continuity, so this measurement can completely satisfy the demand of analysis in field.
Guang pu xue yu guang pu fen xi = Guang pu 07/2009; 29(7):1872-5. · 0.84 Impact Factor
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ABSTRACT: The present paper introduced a FTIR scanning imaging system. This system is based on the combination of a FTIR spectrometer and a scanning mirror. So it has the advantage of FTIR spectrometer: non-contact, real-time, celerity, nicety and high sensitivity. Through scanning mirror, the authors can obtain the space information of targets. The authors used this system to measure the flames infrared emission spectra of three alcohol burners at a flat roof in our laboratory. According to Planck's law, the authors calculated the relative temperature of from each spectrum. These temperature data formed an array. The authors used matlab software to plot the infrared images of target and contrasted them with video image. They were consistent with each other very well. This experiment allowed us to obtain the temperature distribution of three alcohol burners' flames, and provide identification, visualization, and quantification of pollutant clouds.
Guang pu xue yu guang pu fen xi = Guang pu 12/2008; 28(11):2520-2. · 0.84 Impact Factor
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ABSTRACT: FTIR Technique has developed rapidly since 1980s, and has become increasingly important. It has been used in a variety of fields. In order to make sure the result is of nicety, the authors should manipulate the FTIR spectrometer accurately and study its instrument response function and calibration arithmetic. Because the instrument response of the detector of FTIR spectrometer is different at different wave band, the no-calibrated spectrum was ruleless. Without calibration, we can not obtain the absolute intensity, even relative intensity. There are two calibration arithmetics: Linear calibration arithmetic corresponding linear detector and non-calibration arithmetic corresponding non-linear detector. The present paper gave the arithmetic of linear calibration and non-linear multiple point calibration. The authors measured several blackbody spectra at some different temperatures. Some of them were used for calibration and one was used to test the result of calibration The result indicated that this method of non-linear multiple point calibration was very good. The relative arbitrary between calibrated blackbody spectrum and standard blackbody spectrum was near 0.2%, while the maximum was still lower than 0.4%.
Guang pu xue yu guang pu fen xi = Guang pu 10/2008; 28(9):2077-80. · 0.84 Impact Factor
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ABSTRACT: FTIR spectrometer detectors have different instrument response function in different wave band. In application, no matter absolute or relative intensity of spectrum the authors use, the authors should calibrate the instrument with standard blackbody to find the instrument response function. In the present paper, the authors study the instrument response function of detectors (InSb detector and MCT detector) in Canada MOMAN MR154 FTIR spectrometer. The authors found the law of the change in instrument response function with temperature (radiation brightness). It is important for FTIR spectrometer calibration.
Guang pu xue yu guang pu fen xi = Guang pu 09/2008; 28(8):1786-9. · 0.84 Impact Factor
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ABSTRACT: Water vapor absorption, which exists in mid-infrared region, is an interferential element for infrared spectra analysis. A new method, which can be used to eliminate the water vapor interference in FTIR measurement, is presented. To calculate the high resolution absorbance of water vapor, a fast line by line method which computed with the HITRAN database (eg. line strength, self broadening, air broadening, etc) and meteorological parameters (eg. temperature, pressure, and relative humidity) was used. After convolving with Instrumental line shape (eg. divergence angle, resolution, etc), the absorbance of water vapor was then transferred from high resolution to low resolution, which matched the instrumental parameters. After the acquirement of water vapor absorbance spectrum, it will be subtracted from the measured spectrum to calculate the spectrum with the water vapor was eliminated. In the present work, analysis of measured data from open path FTIR is described. Only the absorbing character and noise was left in the spectrum after eliminating the water vapor interference. Consequently, this method has an ideal effect on water vapor elimination when there is no dryer can be used, especially in the case of open path FTIR measurement.
Guang pu xue yu guang pu fen xi = Guang pu 06/2008; 28(5):1052-6. · 0.84 Impact Factor
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ABSTRACT: The present paper analyzed the molecular spectra theory detailedly and summarized the factors affecting the structure and intensity-distribution of molecular rotation-vibration spectra. The authors knew that every spectral line's relative intensity is only related to external temperature. According to this conclusion. The authors showed a new method for measuring the temperature of hot gas by FTIR spectrometry. The authors established a database for measuring the temperature-database using the database of HITRAN. The authors calibrated and validated the database using four experimental spectral data at different temperatures. After calibration, the result was very good. Compared with molecular rotation-vibration emission spectra method and maximum spectral line intensity method, this method has many advantages: simple physical-contents, easy calculation (done by a C program), high precision etc. It was a simple and applied method.
Guang pu xue yu guang pu fen xi = Guang pu 05/2008; 28(4):770-4. · 0.84 Impact Factor
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ABSTRACT: Recently, the greenhouse effect is well known and is of great worldwide concern. CO2 and CH4 are two of the main human activity-induced greenhouse gases in the atmosphere. It is important for environmental scientists to monitor their long-term variation. A Fourier transform infrared spectrometer was used to monitor the concentrations of CO2 and CH4 at a specific site in Beijing. The pollution air was passed through a long open path and the absorption spectra were collected over a period of a month. Quantitative analysis was performed by means of the nonlinear least square method using synthetically generated spectra, which was than convolved with instrumental line shape function. Ambient levels of CO2 and CH4 are reported with a time resolution of five minutes for 4-10, September 2005, and some analysis is present.
Guang pu xue yu guang pu fen xi = Guang pu 06/2007; 27(5):889-91. · 0.84 Impact Factor
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ABSTRACT: Methane (CH4) is an important greenhouse gas and a key molecule in tropospheric photochemistry, some more potent than CO2. The remote-sensing experiments of CH4 were carried out in the fall of 2 000 in Beijng. The 6-day records of the atmospheric CH4 concentrations were examined by means of a time-series analysis using a fast Fourier transform with a low-pass filter to elucidate the seasonal cycles and the long-term trends. The variation in the long-time trends of the CH4 concentrations in Beijing may be ascribed to the emission changes in the CH4 sources due to the human activities such as waste dumping and landfills and the emission from motor vehicles. The correlation between the CH4 and CO concentrations was analyzed.
Guang pu xue yu guang pu fen xi = Guang pu 05/2007; 27(4):668-70. · 0.84 Impact Factor
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ABSTRACT: In active infrared remote sensing measurements, the infrared absorption caused by the presence of trace gases in atmosphere is related to the transmittance spectra in different infrared wave band. In many cases, transmittance spectra play an important role in spectsal quantitative analysis. Thus, the selection of wave band to be optimized for the measured and simulated transmittance spectra is the key in quantitative analysis. In the present paper, the optimal measurement range of transmittance is analyzed theoretically, which causes the minimum relative error of the retrieved concentration. The cross section for the measured gas based on Lorentz line shape is derived by calculation. At the same time, the transmittance spectra calibration training set is presented. The measured and analyzed band is determined for single component CO2. The optimal measurement band is determined for multi-component measurement. The simultaneous measurement of CO, CO2 and N2O with open path FTIR spectrometer system is accomplished successfully. The measured transmittance spectra are in good agreement with the reference transmittance spectra. The root mean square error of fitting results is less than 1%.
Guang pu xue yu guang pu fen xi = Guang pu 05/2007; 27(4):679-82. · 0.84 Impact Factor
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ABSTRACT: In the remote-sensing experiments of CO2 in Beijng, the authors found that the higher concentration of CO2 in autumn is caused by the CO2 emission by the traffic sector during the day time. During the day time, the concentratration of CO2 is comparatively lower because of the photochemistry and the transportation of troposphere. And the concentration of CO2 is about 410 microg x mL(-1). At night the fossil fuel power plants will be taken as a model for the source of CO2, so the concentration of CO2 is about 610 microg x mL(-1) or higher. The carbon increment from increased photosynthesis is greater than the increment in ecosystem carbon stocks. The higher the temperature, the lower the CO2 concentration. And the lower the rate of wind, the higher the concentration of CO2 also. Besides, the concentration of CO2 is affected by some other weather factors.
Guang pu xue yu guang pu fen xi = Guang pu 04/2007; 27(3):452-5. · 0.84 Impact Factor
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ABSTRACT: A long open path fourier transform infrared spectroscopy system is described. The 250-meter-optical-path configuration is combined with a Fourier transform spectrometer of 1 cm(-1) resolution. With an active blackbody source, the transmittance spectrum of the atmosphere could be measured by the system. And then, it was fitted with the nonlinear least square algorithm to calculate the average concentrations of the constituents in the path. Measuring result of some gases such as CH4, CO, N2O and CO2 in polluted air was presented in the experiment part and the RMS of the residuals was <1%. The result shows that the system is stable and rapid, and can be easily aligned. It is suitable for research work on some infrared active important atmospheric constituents.
Guang pu xue yu guang pu fen xi = Guang pu 03/2007; 27(3):448-51. · 0.84 Impact Factor
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ABSTRACT: The MALT-CLS method for quantitative analysis of atmosphere trace gas by FTIR spectrometry was studied. Some experiments are described, such as long-path White cell, and passive remote sensing of aircraft. The characteristic of this method is that the calibration spectra are calculated from a database of absorption line parameters HITRAN using MALT program, including environmental and instrumental effects in the calculation. It is particularly useful in long open-path and solar FTIR spectroscopy, or passive remote sensing by FTIR.
Guang pu xue yu guang pu fen xi = Guang pu 08/2006; 26(7):1213-6. · 0.84 Impact Factor
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ABSTRACT: The present article describes the experiment of airborne Fourier transform infrared (FTIR) spectrometer detecting the background radiation of earth and atmosphere. Considering the surface radiation and atmospheric absorbance and emission, the expression of radiations measured by airborne FTIR is given. It is indicated that the background radiations depend on four parameters: surface temperature, surface emissivity, atmospheric transmission and temperature. Based on theoretic analysis the measured spectra are compared and analyzed according to the differences in altitude and surface. Spectral characters of infrared background radiation are described.
Guang pu xue yu guang pu fen xi = Guang pu 07/2006; 26(6):1018-21. · 0.84 Impact Factor
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ABSTRACT: The phase shift in complex spectrum of Fourier transform infrared (FTIR) spectrometer was discussed. A rigorous derivation showed the relation between the phase shift and complex spectrum. The reason for the radiation offset in FTIR measurement was analysed. The present article presents a calibration method of FTIR complex spectrum, which can adjust the radiation offset. The comparison between experiment data and theoretical computation showed that the method is precise.
Guang pu xue yu guang pu fen xi = Guang pu 04/2006; 26(3):430-3. · 0.84 Impact Factor
