Data analysis and uncertainty estimation in supercontinuum laser absorption spectroscopy

Area of Science:

• Spectroscopy
• Laser Physics
• Analytical Chemistry

Background:

• Super continuum laser absorption spectroscopy (SCLAS) is a powerful technique for gas analysis.
• Accurate evaluation of SCLAS measurements typically requires simultaneous background intensity measurements, complicating experimental setups.
• Existing methods may lack robustness in determining the spectrometer's instrument function.

Purpose of the Study:

• To develop and present algorithms for evaluating SCLAS measurements without simultaneous background intensity measurements.
• To provide a method for in-situ determination of the spectrometer's instrument function.
• To assess the measurement precision of the proposed evaluation approach.

Main Methods:

• A non-linear model fitting approach is employed for spectral data evaluation.
• The influence of the spectrometer's instrument function is analyzed.
• In-situ determination of the instrument function is achieved without additional hardware.
• Error propagation through the non-linear model is used for precision assessment.

Main Results:

• Algorithms facilitate SCLAS measurement evaluation for temperature, pressure, and species concentration.
• The method eliminates the need for simultaneous background intensity measurements.
• In-situ instrument function determination is demonstrated.
• Validation using methane gas cell measurements up to 8.7 bar shows reliable performance.

Conclusions:

• The presented algorithms offer a simplified and precise method for SCLAS data evaluation.
• The approach is transferable to other spectroscopic techniques requiring instrument function determination.
• This work advances the applicability of SCLAS in various gas analysis scenarios.