Pikosekunden‐spektroskopische Untersuchungen an 1‐Phenylazo‐2‐naphtholen

Abstract

Picosecond Spectroscopic Investigations of 1‐Phenylazo‐2‐naphthols The photoisomerization of substituted 1‐phenylazo‐2‐naphthols is studied in fluid solution and in polymer film (cellulose acetate). With the help of picosecond spectroscopy the absorption from an excited state, bleaching, and time resolved fluorescence were measured. The results can be interpreted by the assumption that during periods of less than 10 ps, the S1‐state of the azo form is changed to the S1‐state of the hydrazone form by proton transfer. This S1‐state relaxes by internal conversion and by diabatic isomerization with a time constant of 20 to 60 ps, depending on substituent and solvent. By exciting the substances solved in polymer film, we observed a relatively strong fluorescence, which is found to be amplified spontaneous emission (superfluorescence).