Raman phonon spectra of 7-methoxycoumarin in the lattice phonon region
have been measured in the range 0-5 GPa. A model atom-atom Buckingham
potential has been determined to calculate structural parameters and
Raman-active lattice phonons at ambient conditions and under pressure
up to 14 GPa. The agreement with experiment is satisfactory. Results a
re discussed with reference to the mechanism of the non-topochemical p
hotodimerization which is confirmed to occur via defect sites of the c
rystal rather than as a phonon-assisted process.