Author:
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ISBN:
Category :
Languages : en
Pages :
Book Description
The properties of millimeter-wave spectrometers as highly specific and sensitive experimental research tools for monitoring gaseous pollutants of interest in pollution research are presented. A spectrometer system operating at frequencies in the vicinity of 70 GHz and employing a semi-confocal Fabry--Perot resonator as the sample cell is described. The resonator is voltage tuned by means of a piezoelectric transducer which enables it to track the microwave source frequency. The operation and performance of the spectrometer are discussed and illustrated by measurements of diluted samples of sulfur dioxide. The noise from the microwave source, the absorption cell and the receiver, which ultimately limits the achievable sensitivity are discussed along with considerations for future sensitivity improvements.
Detection and Measurements of Air Pollutants and Constituents by Millimeter-wave Microwave Spectroscopy
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The properties of millimeter-wave spectrometers as highly specific and sensitive experimental research tools for monitoring gaseous pollutants of interest in pollution research are presented. A spectrometer system operating at frequencies in the vicinity of 70 GHz and employing a semi-confocal Fabry--Perot resonator as the sample cell is described. The resonator is voltage tuned by means of a piezoelectric transducer which enables it to track the microwave source frequency. The operation and performance of the spectrometer are discussed and illustrated by measurements of diluted samples of sulfur dioxide. The noise from the microwave source, the absorption cell and the receiver, which ultimately limits the achievable sensitivity are discussed along with considerations for future sensitivity improvements.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The properties of millimeter-wave spectrometers as highly specific and sensitive experimental research tools for monitoring gaseous pollutants of interest in pollution research are presented. A spectrometer system operating at frequencies in the vicinity of 70 GHz and employing a semi-confocal Fabry--Perot resonator as the sample cell is described. The resonator is voltage tuned by means of a piezoelectric transducer which enables it to track the microwave source frequency. The operation and performance of the spectrometer are discussed and illustrated by measurements of diluted samples of sulfur dioxide. The noise from the microwave source, the absorption cell and the receiver, which ultimately limits the achievable sensitivity are discussed along with considerations for future sensitivity improvements.
Millimeter-wave Spectrometer for Pollution Research
Noise Considerations in Millimeter-wave Spectrometers
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
An improved version of a microwave spectrometer operating in the vicinity of 70 GHz is described. The spectrometer, which incorporates a Fabry-Perot resonator and superheterodyne detection for high sensitivity is designed for the detection of gaseous pollutants and other atmospheric constituents. The instrument is capable of detecting polar molecules with absorption coefficients as small as 2 x 10−9cm−1. For sulphur dioxide diluted in air, this sensitivity corresponds to a detection limit of 1.2 ppm without preconcentration and with a time constant of 1 second. Measurements and analysis of the noise contributions limiting the sentivity are presented.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
An improved version of a microwave spectrometer operating in the vicinity of 70 GHz is described. The spectrometer, which incorporates a Fabry-Perot resonator and superheterodyne detection for high sensitivity is designed for the detection of gaseous pollutants and other atmospheric constituents. The instrument is capable of detecting polar molecules with absorption coefficients as small as 2 x 10−9cm−1. For sulphur dioxide diluted in air, this sensitivity corresponds to a detection limit of 1.2 ppm without preconcentration and with a time constant of 1 second. Measurements and analysis of the noise contributions limiting the sentivity are presented.
Energy Research Abstracts
Scientific and Technical Aerospace Reports
Millimeter and Submillimeter Wave Absorption by Atmospheric Pollutants and Constituents
Author:
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Category :
Languages : en
Pages :
Book Description
Calculated absorption coefficients and rotational transition frequencies are given for a number of polar molecules of interest to pollution and energy research. The results, which are presented in graphical form for microwave frequencies up to 1400 GHz, illustrate the increased absorption line intensities occurring in the submillimeter region. For most species these absorption coefficients attain their maximum values in this region. Included in the calculations are the gases SO2, H2CO, O3, H2O, H2S, OCS, CO, NO, OH, SO, NH3, and CS. A discussion of the techniques currently available for the detection in the submillimeter region of these species is also given.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Calculated absorption coefficients and rotational transition frequencies are given for a number of polar molecules of interest to pollution and energy research. The results, which are presented in graphical form for microwave frequencies up to 1400 GHz, illustrate the increased absorption line intensities occurring in the submillimeter region. For most species these absorption coefficients attain their maximum values in this region. Included in the calculations are the gases SO2, H2CO, O3, H2O, H2S, OCS, CO, NO, OH, SO, NH3, and CS. A discussion of the techniques currently available for the detection in the submillimeter region of these species is also given.
Sensitivity and Response Time Improvements in Millimeter-wave Spectrometers
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A new version of a microwave spectrometer for the detection of gaseous pollutants and other atmospheric constituents is described. The spectrometer, which operates in the vicinity of 70 GHz, employs a Fabry-Perot resonator as a sample cell and uses superhetrodyne detection for high sensitivity. The spectrometer has been modified to incorporate a frequency doubler modulated at 30 MHz to permit operation with a single Gunn oscillator source. As a result, faster response time and somewhat greater sensitivity are obtained. The spectrometer is capable of detecting a minimum concentration of 1 ppM of SO2 diluted in air with a 1 second time constant. For OCS diluted in air, the minimum detectable concentration is 800 ppB and with a 10 second time constant 300 ppB.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A new version of a microwave spectrometer for the detection of gaseous pollutants and other atmospheric constituents is described. The spectrometer, which operates in the vicinity of 70 GHz, employs a Fabry-Perot resonator as a sample cell and uses superhetrodyne detection for high sensitivity. The spectrometer has been modified to incorporate a frequency doubler modulated at 30 MHz to permit operation with a single Gunn oscillator source. As a result, faster response time and somewhat greater sensitivity are obtained. The spectrometer is capable of detecting a minimum concentration of 1 ppM of SO2 diluted in air with a 1 second time constant. For OCS diluted in air, the minimum detectable concentration is 800 ppB and with a 10 second time constant 300 ppB.