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Temperature dependent structured absorption spectra of molecular chlorine
I A K Young1, C Murray, C M Blaum
1Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
Physical Chemistry Chemical Physics : PCCP
|July 28, 2011
Summary
This study presents a new dual spectrometer for measuring molecular chlorine absorption. The system provides the first temperature-dependent, vibronically resolved cross sections for chlorine in the visible spectrum.
Area of Science:
- Spectroscopy
- Atmospheric Chemistry
- Physical Chemistry
Background:
- Molecular chlorine (Cl2) plays a role in atmospheric chemistry.
- Accurate absorption cross sections are crucial for atmospheric modeling.
- Previous measurements of Cl2 absorption in the visible spectrum are limited.
Purpose of the Study:
- To design and construct a dual wavelength spectrometer system.
- To measure temperature-dependent absorption cross sections of Cl2 in the green visible spectrum.
- To provide vibronically resolved spectral data for atmospheric and chemical research.
Main Methods:
- Simultaneous UV absorption spectroscopy and cavity enhanced absorption spectroscopy (CEAS).
- Measurement of Cl2 absorption spectra in the 509-570 nm range.
- Laboratory experiments conducted at four temperatures (298 K, 273 K, 233 K, and 197 K).
Main Results:
- The absorption spectrum of molecular chlorine was measured using CEAS.
- Absolute absorption cross sections were determined by simultaneous UV measurements for Cl2 concentration.
- The first temperature-dependent, vibronically resolved Cl2 absorption cross sections in this region were obtained.
- Spectral modeling of the Cl2 B(3)Π(0u+)-X(1)Σg(+) transition showed good agreement with experimental data.
Conclusions:
- The developed dual spectrometer system is effective for simultaneous UV and CEAS measurements.
- The obtained temperature-dependent Cl2 absorption cross sections provide valuable data for atmospheric and chemical studies.
- The results validate spectral modeling of the Cl2 electronic transition.
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