PHYS 372 |
| Photo-generated acids were used at cryogenic temperatures to observe proton transfer by temperature-derivative spectroscopy. Compounds including o-nitrobenzaldehyde, 2,4-dinitrobenzaldehyde, and 5-hydroxy-2-nitrobenzaldehyde were photolyzed and used as proton donors in a deuterated water/glycerol solution with acetate as the proton acceptor. A sample containing acetate and one of the photo-generated acid donors was placed inside of a liquid nitrogen cryostat mounted to an FT-IR and cooled to 130 K. The sample was then exposed to UV light, which causes photoisomerization in nitrobenzaldehydes to form a benzoic acid derivative capable of donating a proton. The sample was then slowly warmed and its IR monitored continuously. Between 170 and180 K, a decrease in absorbance at 1555 cm-1 was observed due to protonation of acetate with a concomitant decrease in absorbance of the photo-generated acid. This method will later be applied in complex environments to observe intermediates and pathways in proton transfer reactions. |
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PHYS Poster Session - General Experiment
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Division of Physical Chemistry |