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Picosecond pump-probe absorption spectroscopy in gases: models and experimental validation
Thomas B Settersten1, Mark A Linne
1Center for Combustion and Environmental Research, Colorado School of Mines, Golden, USA.
Applied Optics
|May 25, 2002
Summary
Picosecond pump-probe absorption spectroscopy offers accurate species concentration measurements without calibration. This technique minimizes collisional effects, enhancing reliability in flame and atomic vapor cell applications.
Area of Science:
- Atomic spectroscopy
- Laser-based analytical techniques
- Physical chemistry
Background:
- Picosecond pump-probe absorption spectroscopy is a spatially resolved technique.
- It measures species concentrations absolutely, without calibration.
- Sensitivity to collisional effects like electronic quenching can be reduced.
Purpose of the Study:
- To model and experimentally characterize picosecond pump-probe absorption spectroscopy.
- To investigate the technique's applicability and limitations.
- To validate the model with experimental data.
Main Methods:
- Developed a model from rate equations describing pump and probe pulse interactions.
- Used density-matrix equations to determine model applicability limits.
- Performed experiments using 1.3-ps and 65-ps pulses on potassium in a flame and atomic vapor cell.
Main Results:
- The developed model shows excellent agreement with experimental data.
- The technique effectively detects potassium in both flame and atomic vapor cell environments.
- Reduced sensitivity to collisional effects was observed with short laser pulses.
Conclusions:
- The picosecond pump-probe absorption spectroscopy model is validated.
- The technique is reliable for absolute species concentration measurements.
- This method is suitable for analyzing species in challenging environments like flames.