Photoacoustic distributed feedback laser spectroscopy on hydrogen fluoride

Area of Science:

• Spectroscopy
• Laser Physics
• Molecular Physics

Background:

• Accurate measurement of molecular absorption line parameters is crucial for various scientific applications.
• Hydrogen fluoride (HF) overtone transitions provide valuable insights into molecular interactions.
• Nitrogen (N2) is a common atmospheric component, making its collisional effects on HF important to study.

Purpose of the Study:

• To develop and utilize a photoacoustic spectrometer with a tunable distributed feedback (DFB) diode laser.
• To precisely determine the absorption line parameters of hydrogen fluoride (HF) rotational lines.
• To investigate the effects of nitrogen (N2) collisions on HF absorption lines, including pressure broadening and line shifts.

Main Methods:

• Development of a photoacoustic spectrometer utilizing a distributed feedback (DFB) diode laser with continuous tunability over 700 GHz.
• Experimental measurements on the P2 and P3 rotational lines of the HF 2-0 vibrational transition (overtone) at specific vacuum wavelengths (1304.534 nm and 1312.591 nm).
• Analysis of spectral data to determine pressure broadening coefficients and Doppler linewidths due to N2 collisions, as well as pressure-induced line shifts.

Main Results:

• The pressure broadening coefficient due to N2 collisions was determined for HF rotational lines P2 and P3.
• Doppler linewidths for these HF lines were measured at 296 K.
• Pressure-induced line shifts of the HF absorption lines caused by N2 were quantified.

Conclusions:

• The developed photoacoustic spectrometer enables precise determination of molecular absorption line parameters.
• The study provides quantitative data on the collisional broadening and shifting of HF lines by N2.
• These findings contribute to a better understanding of molecular interactions and spectral line shapes.