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Photon flux measurements using calorimetry.
1Department of Chemistry, California State University-Fullerton, California.
The Review of Scientific Instruments
|October 1, 1979
Summary
A new photometric calorimeter accurately measures light intensity by converting light into heat. This device offers precise photon flux measurements across the optical spectrum, proving valuable for various scientific applications.
Area of Science:
- Photochemistry and Photophysics
- Chemical Thermodynamics
- Optical Instrumentation
Background:
- Accurate measurement of light intensity (photon flux) is crucial for understanding photochemical reactions and optical processes.
- Existing methods may have limitations in sensitivity, spectral range, or ease of use.
- Development of simple, reliable instruments for photon flux determination is an ongoing need in scientific research.
Purpose of the Study:
- To design and construct a simple photometric calorimeter for measuring photon flux.
- To evaluate the performance and accuracy of the constructed calorimeter.
- To demonstrate its utility across a broad optical spectral range.
Main Methods:
- A vacuum-jacketed cell with quartz windows was employed to contain the sample.
- A thermistor probe monitored temperature changes resulting from light absorption.
- A built-in resistance heater allowed for instrument calibration.
Main Results:
- The photometric calorimeter quantitatively converts absorbed incident radiation into heat.
- Photon flux measurements demonstrated agreement with established ferrioxalate actinometry at 366 and 436 nm.
- The instrument achieved a sensitivity of 2x10^15 photons/s.
Conclusions:
- The constructed photometric calorimeter provides accurate photon flux measurements.
- The device is effective and reliable for use throughout the optical spectral range.
- This simple calorimeter is a valuable tool for quantitative light measurements in scientific studies.
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