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INVESTIGATION OF POWER ABSORPTION BY METHYLENE BLUE IN A LIGHT SCATTERING MEDIUM WITH AN INTERNAL PHOTODYNAMIC ACTINOMETER
Author(s) -
Grossweiner Leonard I.,
Messina James W.
Publication year - 1987
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1987.tb07388.x
Subject(s) - actinometer , absorption (acoustics) , optics , penetration (warfare) , penetration depth , materials science , attenuation coefficient , methylene blue , absorbance , optical power , chemistry , diffusion , scattering , light scattering , analytical chemistry (journal) , chromatography , laser , physics , plasma , thermodynamics , biochemistry , operations research , quantum mechanics , photocatalysis , engineering , catalysis
— Power absorption by aqueous solutions of methylene blue containing high concentrations of polystyrene microspheres was measured at 650 nm, using the photosensitized inactivation of subtilisin Carlsberg as an internal actinometer. The results were analyzed with the one‐dimensional diffusion approximation for a finite slab. It is shown that the power absorption is determined by two macroscopic parameters, the optical penetration depth and the linear absorption coefficient. The optical penetration depth was determined independently by measuring flux profiles with an inserted fiber‐optic method. The results are in satisfactory agreement with the predictions of the diffusion model, with microsphere diameters from 0.5 to 5 μm and a wide range of scatterer and dye concentrations. The presence of the scatterers diminished the power absorbed by the dye in all cases. The predictions of one‐dimensional diffusion model are compared to Kubelka‐Munk theory, and shown to be equivalent for optically dense systems