TRANSITION-STATE SPECTROSCOPY VIA NEGATIVE-ION PHOTODETACHMENT

In this Account, we have briefly described three examples in which negative ion photodetachment is used to probe the transition-state region of a bimolecular reaction. The examples illustrate that photoelectron spectroscopy and threshold photodetachment spectroscopy can yield vibrational structure and dissociation dynamics associated with the transition state. The three examples also show the importance of anion geometry, as this determines which region of the neutral potential energy surface is accessible via photodetachment. This last point is, in fact, one of the most important limitations of these experiments. One way to mitigate this problem is to perform photoelectron spectroscopy studies on vibrationally excited anions. Photodetachment of these anions will probe different vibrational levels and geometries of the neutral transition state. Such studies are planned for the near future. © 1993, American Chemical Society. All rights reserved.