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It is shown that the observation of the degree of polarization of the fluorescence of 9,9′‐spirobifluorene VI and of 2,2′‐diamino‐7,7′‐dinitro‐9,9′‐spirobifluorene VII allows a determination of the rate constant for energy transfer from the initially excited to the unexcited part. The rate constants are of the order of 108 s−1 for VI and 3 · 109 s−1 for VII. The corresponding electronic matrix elements of interaction are evaluated. They are rather due to the Coulomb‐interaction of the transition densities than to spiroconjugation. In VI the coupling vanishes in the equilibrium conformation, vibronic effects must be evoked for explaining its existence.

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