Award Address (E. Bright Wilson Award in Spectroscopy, sponsored by the American Chemical Society). Ultrafast 2-D infrared vibrational echo chemical exchange spectroscopy studies of chemical processes

Many important chemical processes occur in room temperature liquids on fast time scales under thermal equilibrium conditions. Two such processes are the formation and dissociation of organic solute-solvent complexes and the rotational isomerization around a carbon-carbon single bond. These processes can now be studied using ultrafast 2D infrared vibrational echo chemical exchange experiments. Eight solute-solvent systems composed of phenol and derivatives (solutes) in mixed solvents of benzene and derivatives with CCl4 are studied. Complex formation and dissociation on the picosecond time scale is directly related to the complex formation enthalpies. Insights are gained from simulations. The first direct measurement is made of low barrier height gauche-trans isomerization around a carbon-carbon single bond of a substituted ethane in a room temperature liquid. The results are compared to theoretical calculations from the literature on a similar isomerization and used to estimate the isomerization time ethane would have in room temperature liquid solution.