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Multi-mode absorption spectroscopy using a quantum cascade laser for simultaneous detection of NO and H2O.
S O'Hagan1, T Pinto2, P Ewart1
11Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford, OX1 3PU UK.
Applied Physics. B, Lasers and Optics
|May 2, 2020
Summary
This study demonstrates multi-mode absorption spectroscopy (MUMAS) for detecting NO and H2O transitions using a quantum cascade laser (QCL). The method achieves high scan rates, enabling detailed analysis of laser mode structures for accurate spectral fitting.
Area of Science:
- Spectroscopy
- Laser Technology
- Atmospheric Chemistry
Background:
- Accurate detection of trace gases like NO and H2O is crucial for environmental monitoring and industrial process control.
- Quantum cascade lasers (QCLs) offer tunable mid-infrared output suitable for molecular spectroscopy.
- Multi-mode absorption spectroscopy (MUMAS) presents a promising technique for rapid gas analysis.
Purpose of the Study:
- To report the detection of multiple transitions in nitric oxide (NO) and water (H2O) using MUMAS.
- To investigate the performance of a quantum cascade laser (QCL) operating at 5.3 μm for high-speed spectroscopic measurements.
- To analyze the spectral structure of the QCL output for accurate data fitting.
Main Methods:
- Utilized multi-mode absorption spectroscopy (MUMAS) with a quantum cascade laser (QCL).
- Operated the QCL at 5.3 μm with scan rates up to 10 kHz.
- Derived QCL longitudinal mode linewidths from pressure-dependent MUMAS data fits.
Main Results:
- Successfully detected multiple absorption transitions for NO and H2O.
- Achieved high scan rates of up to 10 kHz, enabling rapid spectral acquisition.
- Analyzed variations in the QCL's broadband, multi-mode output for precise spectral modeling.
Conclusions:
- MUMAS with a QCL is effective for detecting multiple gas transitions at high speeds.
- Understanding QCL spectral characteristics is vital for accurate spectroscopic analysis.
- The developed method shows potential for advanced gas sensing applications.
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