The study of non-radiative intra-molecular energy transfer is of industrial importance (dye lasers, mode-selective chemistry) and academic interest. I propose to use a novel combination of laser induced fluorescence and opto-thermal detection to look at two prototypical systems. The methods are complimentary: internal energy which is not lost through emission remains in the molecule to be detected opto-thermally. Measurements of rotational linewidths and structure at high resolution ( lMHz) will enable the coupling mechanisms between the excited and ground states to be determined.
The molecule CF3NO is a testing ground for theories of photodissociation. Using opto-thermal detection, the key transitions at the energy threshold for the process will be observable for the first time, as lost kinetic energy from the molecular beam. Pyridine has a very weak fluorescence spectrum, owing to extremely efficient intra-molecular energy transfer, which make it difficult to study at high resolution by normal techniques but ideal for opto-thermal detection.