Gaseous trace analysis using pulsed photoacoustic Raman spectroscopy

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Environmental Science

Background:

• Trace gas analysis is crucial for environmental monitoring and industrial processes.
• Existing techniques like direct absorption and other Raman methods have limitations in sensitivity or applicability.

Purpose of the Study:

• To introduce and detail a new method for trace gas analysis using pulsed photoacoustic Raman spectroscopy (PARS).
• To evaluate the sensitivity and analytical capabilities of the PARS technique.
• To compare PARS with other spectroscopic methods for gas analysis.

Main Methods:

• Utilized pulsed photoacoustic Raman spectroscopy (PARS) for gas detection.
• Applied the PARS method to analyze mixtures of CH(4) in N(2), CO(2) in N(2), and N(2)O in N(2).
• Investigated apparatus details, sensitivity improvements, and limiting factors.

Main Results:

• Successfully applied PARS to analyze gas mixtures at concentrations near 1 ppm.
• Evaluated means to enhance sensitivity and identified sensitivity-limiting processes.
• Compared the analytical performance of PARS with direct IR absorption, CARS, and SRGS.

Conclusions:

• Pulsed photoacoustic Raman spectroscopy (PARS) is a viable technique for trace gas analysis.
• The PARS method demonstrates potential for sensitive detection of specific gases at low concentrations.
• PARS offers competitive analytical capabilities compared to other Raman and IR techniques.