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Velocity measurements by cavity ringdown spectroscopy.
1Department of Mechanical Engineering, Colorado State University, Fort Collins 80523, USA. ayalin@engr.colostate.edu
Optics Letters
|December 14, 2005
Summary
Cavity ringdown spectroscopy (CRDS) enables direct gas-phase particle velocity measurements. This technique infers velocity from Doppler shifts in absorption line shapes, avoiding external frequency references.
Area of Science:
- Atomic Physics
- Spectroscopy
- Physical Chemistry
Background:
- Cavity Ring-Down Spectroscopy (CRDS) is a sensitive absorption technique.
- Doppler shifts in spectral lines provide information about particle velocity.
- Measuring gas-phase particle velocity is crucial in various scientific fields.
Purpose of the Study:
- To demonstrate a novel method for gas-phase particle velocity measurement using CRDS.
- To leverage Doppler-shift contributions to absorption line shapes for velocity determination.
- To validate the CRDS velocity measurement technique in a collisionless environment.
Main Methods:
- Utilizing Cavity Ring-Down Spectroscopy (CRDS) for absorption measurements.
- Analyzing the Doppler-shift contributions to the absorption line shape.
- Observing the splitting of absorption features due to velocity components parallel to the optical axis.
Main Results:
- Successful velocity measurements of gas-phase particles were achieved.
- The observed splitting of absorption features directly correlated with particle velocity.
- The method demonstrated direct velocity measurements without external frequency calibration.
Conclusions:
- CRDS is a viable technique for direct velocity measurements of gas-phase particles.
- The Doppler-split absorption feature in CRDS provides a self-referencing velocity measurement.
- This approach is effective in low-pressure, collisionless environments, as shown with sputtered molybdenum atoms.