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Rejection of Fluorescence Background in Resonance and Spontaneous Raman Microspectroscopy
Published on: May 18, 2011
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Note: Rotational Raman scattering on CO₂ plasma using a volume Bragg grating as a notch filter
B L M Klarenaar1, F Brehmer1, S Welzel1
1Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
The Review of Scientific Instruments
|May 3, 2015
Summary
A novel volume Bragg grating notch filter effectively removes Rayleigh scattering and stray light in gas discharges. This allows for precise measurement of rotational Raman spectra and accurate determination of gas temperatures.
Area of Science:
- Spectroscopy
- Laser Physics
- Materials Science
Background:
- Raman spectroscopy is crucial for analyzing molecular vibrations.
- Rayleigh scattering and stray light can obscure weak Raman signals.
- Accurate temperature measurements in gas discharges are vital for various applications.
Purpose of the Study:
- To develop and demonstrate a novel volume Bragg grating notch filter.
- To effectively suppress Rayleigh scattering and stray light in gas discharge Raman spectroscopy.
- To enable accurate measurement of rotational Raman spectra and gas temperature.
Main Methods:
- Utilized a volume Bragg grating as a notch filter.
- Employed a 532 nm laser for excitation.
- Measured rotational Raman spectra in a CO2 gas discharge.
- Determined rotational temperature from spectral analysis.
Main Results:
- The Bragg grating demonstrated an optical density of 3.1 at 532 nm.
- Achieved a narrow full width at half maximum of 7 cm(-1) for the filter.
- Successfully measured a nearly complete rotational CO2 spectrum.
- Determined the rotational temperature with 2% accuracy.
Conclusions:
- Volume Bragg gratings are highly effective notch filters for Raman spectroscopy.
- The developed method enables undisturbed rotational Raman spectral measurements.
- Accurate gas temperature determination is achievable using this filtering technique.
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