Electron-Molecule Resonances : from DNA to Molecular Hydrogen

Recent findings that electron-molecule resonances form the crucial link in most of the radiation induced damage in DNA and are also the basis for chemical control using electrons have brought them back into limelight after a gap of almost half a century. While resonant attachment of electrons to molecules provides an efficient way of transferring the kinetic energy of the electrons into potential energy of the system, making it chemically more reactive, it is the unique dynamics of the process that provides the scope for chemical control through bond selective fragmentation of the molecule. Several efforts are being directed to make use of this new found route for chemical control in the bulk. At the same time, renewed efforts are on to understand the complex dynamics of the formation and decay of the resonances. The ion momentum imaging technique developed at TIFR has now become one of the most important tool in this respect. While we have obtained considerable details of the dynamics of the resonances in several molecules including bond selective fragmentation, very recent experiments have provided surprising results that challenge some of the long held concepts in electron-molecule collisions. In this talk, I shall try to describe our work in the context of world-wide efforts on electron-molecule collisions and discuss future possibilities.