A quantitative analysis method based on collision broadening for trace gas using terahertz heterodyne spectrometer

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Physical Chemistry

Background:

• Quantitative analysis of trace gases is crucial in analytical chemistry.
• Terahertz electronic spectrometers offer powerful capabilities for trace gas detection.
• Acetonitrile (CH3CN) is a relevant trace gas for analysis.

Purpose of the Study:

• To present a terahertz spectrometer based on frequency multiplier chain and heterodyne detection.
• To develop and validate a novel quantification method for trace gases using broadening mechanisms.
• To measure the rotational spectra of acetonitrile (CH3CN) and determine its collisional broadening coefficients.

Main Methods:

• Utilized a terahertz spectrometer with frequency multiplier chain and heterodyne detection.
• Measured rotational spectra of CH3CN gas in the 290-370 GHz band with 100 kHz resolution.
• Experimentally obtained CH3CN self- and nitrogen (N2)- collisional broadening coefficients.

Main Results:

• The spectrometer demonstrated excellent spectral specificity for CH3CN.
• Extrapolated limit of detection for CH3CN was determined to be 1.4 ppm.
• The novel quantification method achieved a relative error of 0.1% for CH3CN concentration.

Conclusions:

• The developed terahertz spectrometer is highly effective for trace gas analysis.
• The proposed quantification method based on broadening mechanisms is accurate and reliable.
• This approach offers a new perspective for quantitative trace gas analysis.