Optical properties of poly(para-phenylenes) under high pressure

We present optical studies using photoluminescence, absorption and Raman sc attering on samples from two generic families, the polycrystalline para-phe nylene oligomers and the amorphous paraphenylene polymers, under hydrostati c pressure. These studies have provided insight into the geometry of the mo lecules, and the fundamental properties of the ground and excited states of these materials. Using our measurements under pressure and a simple model we extract atmospheric pressure values for the shift in the configuration c oordinate between ground and excited states and the ratio of force constant s describing the potential wells that describe these states.