spectral overlap

In the context of radiative energy transfer, the integral, $J = ∫ 0 ∞ f D ' σ ɛ A σ ⁢ d σ$ , which measures the overlap of the emission spectrum of the excited donor, D, and the absorption spectrum of the ground state acceptor, A; $f D '$ is the measured normalized emission of D, $f D ' = f D σ ∫ 0 ∞ f D σ ⁢ d σ$ , $f D σ$ is the photon exitance of the donor at wavenumber $σ$ , and $ɛ A σ$ is the decadic molar absorption coefficient of A at wavenumber $σ$ . In the context of Förster excitation transfer, $J$ is given by:

$J = ∫ 0 ∞ f D ' σ ɛ A σ σ 4 ⁢ d σ$

In the context of Dexter excitation transfer, $J$ is given by:

$J = ∫ 0 ∞ f D σ ɛ A σ ⁢ d σ$

In this case $f D$ and $ɛ A$ , the emission spectrum of donor and absorption spectrum of acceptor, respectively, are both normalized to unity, so that the rate constant for energy transfer, $k ET$ , is independent of the oscillator strength of both transitions (contrast to Förster mechanism).

See: energy transfer

Source:

PAC, 1996, 68, 2223 (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2275