Persistent holes have been burnt in the spectra of post-etiolated maize leaves in the spectral interval 700–745 nm at 5 K. Narrow (< 1 cm−1) holes detectable both in fluorescence and excitation spectra correspond to the zero-phonon purely electronic S1◀S0 transition of chlorophyll a rather than to the S1←S0 vibronic or S 1 ←S0 higher singlet transitions. The spectral composition of the inhomogeneously broadened absorption and fluorescence contours of long-wavelength chlorophyll a forms in plants is discussed in terms of the contributions of phonon-wings, vibronic satellites, purely electronic S1◀S0 transitions and its higher excitonic components.
