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Derivation of new equations for phase-shift cavity ring-down spectroscopy
Graham D Reid1, Michael D Robertson, Anthony Z Tong
1Department of Physics, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6.
The Journal of Physical Chemistry. A
|April 27, 2011
Summary
New phase-shift cavity ring-down spectroscopy (PS-CRDS) equations improve ring-down time measurements for long optical cavities. This advancement enhances accuracy for fiber optic cavities, benefiting on-site chemical sensing applications.
Area of Science:
- Spectroscopy
- Physical Chemistry
- Optical Physics
Background:
- Current phase-shift cavity ring-down spectroscopy (PS-CRDS) relies on equations derived from fluorescence studies.
- These existing equations are inaccurate for longer optical cavities due to neglecting cavity length and beam superposition.
Purpose of the Study:
- To develop new, accurate equations for PS-CRDS based solely on its principles.
- To determine ring-down time using phase shift or waveform intensity from the cavity.
Main Methods:
- Derivation of novel PS-CRDS equations from fundamental principles.
- Comparison of new equations with existing fluorescence-based equations.
Main Results:
- The new PS-CRDS equations accurately determine ring-down time and phase shift for long cavities.
- The derived equations reduce to fluorescence-based equations for short cavities, validating their accuracy.
- Demonstrated improved performance for fiber optic cavities.
Conclusions:
- The developed PS-CRDS equations offer a more precise method for measuring characteristic ring-down time and phase shift.
- This improved accuracy is particularly beneficial for long and fiber optic cavities.
- The findings hold significant promise for advancing on-site chemical sensing technologies.
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