Photophysical characterisation of some dipyrromethene dyes in ethyl acetate and covalently bound to poly(methyl methacrylate)

Analogues of the dipyrromethene-BF2 dye PM567 modified at the 8-position by acetoxymethyl (P1Ac), s-acetoxypentyl (P5Ac), and p-acetoxymethylphenyl (PAr1Ac) groups are studied in ethyl acetate solution. PM567 modified at the 8-position by methacryloyloxymethyl (P1MA), s-methacryloyloxypentyl (P5MA), and p-methacryloyloxymethylphenyl (PAr1MA) groups have been copolymerized with methyl methacrylate (MMA), and these solid samples are also studied. The absorption cross-section and stimulated emission cross-section spectra are determined. The fluorescence quantum distributions and fluorescence lifetimes are measured. Saturable absorption measurements with picosecond laser excitation are carried out for excited-state absorption cross-section determination at the excitation wavelength. The photo-degradation of the dyes is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted.