Aromatic Carbonyl Spectra at High Pressures

The spectra of benzophenone (Snπ*←S0; Tnπ*→S0), fluorenone (Sππ*←S0; Sππ*→S0), and anthrone (Tnπ*→S0) have been studied as a function of pressure to 25 kbar. The π*←n absorption band of benzophenone shows a blue shift in compressed polar and hydrogen-bonding plastics, in contrast to the absorption of fluorenone. The fluorescence of fluorenone shows a red shift for all plastics which is greater than the corresponding red shift in absorption at the same isobar. The phosphorescence also shifts red except for benzophenone in polyethylene, polyacrylonitrile, and polyvinyl alcohol, where an initial blue shift is observed. These plastics are evidently capable of restraining geometrical changes in the benzophenone molecule.