Could you explain the significance of your article to the non-specialist?

Although a great deal is known about the rates of collisional energy transfer from electronically excited states, very few experiments have been carried out to monitor the fate of the energy, in particular when it has to end up as internal excitation in the ground state of the molecule. We are able to look at all vibrationally excited levels of a molecule at the same time using the technique of time resolved FTIR emission spectroscopy, and we have applied this for the first time to learn where electronic energy in the NO molecule ends up when it is collisionally self-quenched.

What has motivated you to conduct this work?

Pure curiosity. The experiments had been tried out with a different technique (laser induced fluorescence) some twenty years ago, and hinted at the rather surprising results that we have now found. It turns out that there are also good technological reasons for doing the measurements (which, of course, would be highlighted in any grant application).

Where do you see this work developing in the future?

Our article describes self quenching of one state of NO, and we have already extended this to quenching by a number of other species (CO, CO₂, Xe, N₂O). We shall look at quenching of different vibrational levels of electronically excited NO, and extend the studies to other molecules, in particular to quenching of the OH radical.

Are there any particular challenges facing future research in this area?

For us the challenge is convincing a research council that fundamental work of this kind is worth doing. The experiments have been done with a laser borrowed from the Rutherford Loan Laser Pool, and at some stage it will have to be returned.