ENERGY TRANSFER MECHANISMS IN LASER DYE MIXTURES

ABSTRACT

Measurements of fluorescence intensities in optically thick (lasing) and thin (non-lasing) solutions and fluorescence lifetimes of donor in binary mixtures of laser dyes have been made. Various energy transfer parameters such as energy transfer rate parameters, critical transfer radii and mean diffusion lengths for four pairs of dyes have been determined. Fluorescence intensities measured for optically thick solutions were corrected to account for radiative transfer and direct absorption of excitation by the acceptor. Energy transfer rate parameters obtained from intensity as well as lifetime measurements strongly support the dominance of energy transfer via resonance mechanism.

Keywords:

• Energy transfer
• Rate constant
• Fluorescence lifetime
• Critical transfer radius
• Mean diffusion length
• Half-quenching concentration

ACKNOWLEDGMENTS

The authors are grateful to the Defence Research & Development Organization, New Delhi and the University Grants Commission, New Delhi, India, for financial support. SRI thanks Dr. N.N. Math for useful discussions.