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IR Spectroscopy in Water

Femtosecond Spectroscopy of Water (HOH, HOD, DOD)

The experiments described above study how energy deposited in a molecule rapidly leaves the molecule, resulting in broken bonds, isomerizations, deexcitations, and interactions with the solvents. Consequently, the solvent - the acceptor of the excess energy - is excited and perhaps it is possible to monitor the uptake of energy by the solvent by studying the femtosecond infrared spectrum of the solvent.

This we recently demonstrated in an experiment on nitrite in water, where we observed a very rapid and efficient excitation of the intermolecular hydrogen bonds of the water solvent. We did not observe specific excitations of the different water modes (stretching and bending), but rather observed a general excitation of all the H-bonds linking the water molecules together.

This is an extremely interesting observation at the heart of chemistry: where does the energy go and why is water so useful as a solvent and as the matrix for life! We are continuing these experiments and are changing both temperature and the isotopic content of water to gain more insight into water and its unique role in chemistry.