Taking a Selective Bite Out of Methane

摘要

For more than a decade, scientists have attempted to use lasers to drive the selectivity of chemical reactions, with mixed success. On page 790 of this issue, Killelea and co-workers report a successful realization of this approach for a surface reaction. For laser-driven selective chemistry to work, the laser must excite a particular vibra-tional mode in a molecule, and the energy must reside in that particular vibrational mode long enough for the molecule to dissociate and/or collide with another reactant molecule or surface. However, the energy in multi-atom molecules may be redistributed as a result of coupling between the vibrational modes in the molecule, and the excitation energy provided by the laser frequently may thus reside only transiently in the desired vibrational mode. As a result, demonstrating bond-selective chemistry of polyatomic molecules has proved harder to achieve than originally imagined.