Matrix isolation-supersonic jet infrared spectroscopy: conformational cooling in trimethyl phosphate

A supersonic jet source has been coupled to a matrix isolation set-up to obtain conformational cooling in organic phosphates. Infrared spectra of trimethyl phosphate (TMP) trapped in a nitrogen matrix using supersonic jet sampling, indicated that the higher-energy conformer of TMP was significantly depopulated, compared with the spectra recorded using the conventional effusive source. The conformational temperature was estimated to be 147 K. This study demonstrates for the first time the successful use of supersonic jet sampling to obtain conformational cooling in molecules where the barrier to conformation interconversion is reasonably large (> ca. 10 kJ mol−1).