Photochemistry on surfaces: Fluorescence emission of monomers and dimers and triplet state absorption of acridine orange adsorbed on microcrystalline cellulose

✍ Scribed by F. Wilkinson; D.R. Worrall; L.F.Vieira Ferreira

• Book ID: 103907694
• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 816 KB
• Volume: 48
• Category: Article
• ISSN: 1386-1425
• DOI: 10.1016/0584-8539(92)80015-o

✦ Synopsis

Ah&r&-Prompt

fluorescence as well as delayed fluorescence emission of acridine orange was detected at room temperature from samples where this dye is adsorbed on microcrystalline ceIIulose. Ground state absorption studies provided evidence for dimer formation of the dye when adsorbed on cellulose, and the equilibrium constant for dimerisation was determined as 1.6fO.l X ldmol-' g. At low loadings of acridine orange on cellulose (20 umol g-i), the fluorescence intensity decreases, and the emission is broad with its maximum at 620 nm, and is mainly due to the dimer. By assuming that the excited monomer and dimer of acridine orange are the only emitting species, it was possible to determine the fluorescence quantum yields for these two species when adsorbed on microcrystalline cellulose as 0.95 f0.05 and 0.4O+O.10, respectively. Pulsed emission studies at room temperature in the millisecond time-range also revealed monomer and dimer emissions on this longer time-scale. These are shown to be due to thermally activated delayed fluorescence arising from the triplet states of monomer and dimer acridine orange as confirmed by diffuse reflectance transient absorption studies.