Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 27: Poster 3: Collisions, Electronic Spectroscopy, Energy Transfer, Quantum Chemistry, Molecular Dynamics, Photochemistry, Spectroscopy in He-Droplets

MO 27.29: Poster

Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof

Cavity ring-down spectroscopy for state resolved monitoring of molecular chlorine in the visible wavelength range — •Ignacio Vespoli1,2, Thomas Forsting1, and Christof Maul11Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig, Germany — 2Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquén, Argentina

State resolved detection of nascent products of chemical reactions and/or photodissociation provides valuable information about the dynamics of the underlying elementary processes. Molecular chlorine is of particular interest for atmospheric chemistry, however, detailed studies have remained scarce due to the lack of suitable optical detection methods.

The weak rovibrational bands in the visible absorption spectrum of chlorine are reexamined from 485 to 505 nm with the highest instrumental resolution yet known (0.001 nm). Due to small absorption cross-sections of about 10−21 to 10−22 cm2 a very sensitive method needs to be employed: Cavity Ring-Down (CRD) Spectroscopy.

The resulting absorption spectrum shows rotationally resolved bands of the spin-forbidden transition B-X. A rovibrational analysis needs to take into account that chorine occurs in three isotopomers 35Cl2, 35Cl37Cl and 37Cl2.

The current detection limit is of the order of 1015 cm−3. The results are a proof of concept as well as a preliminary stage to carry out chemical reactions with in situ detection of gaseous reaction products.

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