Figure 3.

Determination of efficiency of resonance energy transfer by luminescence decay on unfixed muscle sections. Unquenched donor phosphorescence was detected at 547 nm in the presence or absence of acceptor. No donor phosphorescence was detectable at 568 nm, permitting measurement of sensitized emission at 568 nm. Measurements made on large cross-sections of muscle mounted in the luminescence spectrometer. Decay curves were measured in a luminescence spectrometer after flashlamp excitation at 342 nm. Lifetimes were estimated by single exponential curve fitting that yielded 1.80 ± 0.07 ms (r² = 0.984) for unquenched phosphorescence and 0.59 ± 0.03 ms (r² = 0.964), indicating an efficiency of energy transfer, E, of 0.67.