The S-1 excited state and cation ground state of jet-cooled 9-propylfluorene have:been studied using resonance enhanced multiphoton ionization (REMPI) and zero electron kinetic energy (ZEKE) photoelectron spectroscopy. Three conformations of 9-proeylfluorene have been experimentally identified. Quantum chemical calculations have been used to calculate the ground state and cation energies of each conformer as well as the-barrier to conformer interconversion via a bond rotation. ZEKE spectroscopy has also been used to search for conformer interconversion upon vibronic excitation to S-1, but no evidence for a dynamic barrier crossing has been,found,. even at the highest: energy probed (3210 cm(-1)). Similar studies previously carried out on 9-ethylfluorene were also extended to higher energy, and no evidence of dynamic barrier crossing was found at energies as high as 3525 cm(-1). Statistical density of state calculations have been carried out to predict the relative populations of each conformer as a function of excess energy, and the Rice-Ramsperger-Kassel-Marcus (RRKM) isomerization rates have also been calculated.