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Rejection of Fluorescence Background in Resonance and Spontaneous Raman Microspectroscopy
Published on: May 18, 2011
A low cost time-resolved Raman spectroscopic sensing system enabling fluorescence rejection
Joseph V Sinfield1, Oliver Colic, Daniel Fagerman
1School of Civil Engineering, Purdue University, West Lafayette, Indiana 47907-2051, USA. jvs@purdue.edu
Applied Spectroscopy
|February 13, 2010
Summary
A new, low-cost, time-resolved Raman spectroscopy system uses pulsed lasers to minimize fluorescence interference. This enables more affordable and accessible in situ chemical analysis for various applications.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Chemical Sensing
Background:
- Fluorescence often interferes with Raman spectroscopy, complicating chemical analysis.
- Traditional continuous wave (CW) Raman systems can be limited by fluorescence, especially in complex samples.
- Advancements in laser and data acquisition technology offer new possibilities for improving Raman spectroscopy.
Purpose of the Study:
- To develop a novel, compact, and low-cost time-resolved Raman spectroscopy system.
- To minimize the impact of fluorescence on Raman observations for enhanced chemical analysis.
- To create a foundation for affordable in situ and fieldable chemical sensing devices.
Main Methods:
- Utilized a 6.4 kHz repetition rate, 900 ps pulsed diode laser (532 nm).
- Employed time-resolved photon counting with custom and off-the-shelf hardware/software.
- Compared long- and short-gated acquisition scenarios for signal-to-noise ratio (SNR) improvement.
Main Results:
- Demonstrated reduced fluorescence interference in Raman observations.
- Achieved an approximately 15-fold SNR improvement for benzene with a fluorophore using time-resolved photon counting.
- Successfully analyzed complex mixtures like gasoline and identified various compounds (e.g., trichloroethylene, benzene, olive oil).
Conclusions:
- The developed time-resolved Raman system effectively enhances Raman signature quality, particularly in the presence of fluorescence.
- The system offers a cost-effective solution for in situ and fieldable chemical analysis.
- Efficient signal averaging enables low-concentration detection, expanding its utility in diverse settings.
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