Infrared intracavity laser absorption spectroscopy with a continuous-scan Fourier-transform interferometer

Area of Science:

• Spectroscopy
• Atmospheric Science
• Laser Physics

Background:

• High-resolution spectroscopy is crucial for analyzing atmospheric composition.
• Intracavity laser absorption spectroscopy (ICLAS) offers enhanced sensitivity for spectral measurements.
• Fourier-transform (FT) interferometry is a standard technique for spectral analysis.

Purpose of the Study:

• To develop and validate a high-quality broadband infrared high-resolution spectroscopy method.
• To measure the absorption of atmospheric water vapor with high accuracy and sensitivity.
• To compare the performance of the new method with conventional FT techniques.

Main Methods:

• Utilized intracavity laser absorption spectroscopy (ICLAS) with a Ti:sapphire laser.
• Employed a continuous-scan Fourier-transform (FT) interferometer for spectral acquisition.
• Applied electronic filtering to stabilize laser power and improve signal-to-noise ratio.

Main Results:

• Achieved high-resolution spectra (0.05 cm(-1)) in the 12,450-12,700 cm(-1) range.
• Recorded atmospheric water vapor absorption with a signal-to-noise ratio > 300.
• Demonstrated a minimum detectable absorption of approximately 2 x 10(-9) cm(-1).
• Obtained highly accurate line positions and reasonable line intensities compared to conventional FT methods.

Conclusions:

• The ICLAS technique with a continuous-scan FT spectrometer provides superior performance for high-resolution infrared spectroscopy.
• This method enables sensitive and accurate measurements of atmospheric water vapor absorption.
• The technique is suitable for investigating spectral evolution over time using rapid-scan methods.