MULTIPLE FLUORESCENCES IN PARA-N,N-DIETHYLAMINOSALICYLIC ACID

The photophysical properties of para-N,N-diethylaminosalicylic acid (PEAS) have been investigated by steady-state absorption and fluorescence spectroscopies. In n-heptane PEAS exhibits multiple fluorescences. The lower frequency emission band maximum at 450 nm is unambiguously assigned to the tautomer emission resulting from the excited-state intramolecular proton transfer. The normal Stokes-shifted emission is assigned to a dimer emission overlapping with the normal emission of conformer b (or b'). Our result rectifies a previous report which concluded that the short wavelength band originates from amino-N charge-transfer emission.