Evaluation of 2D-ESEEM data of 15N-labeled radical cations of the primary donor P700 in photosystem I and chlorophyll a

Hyperfine couplings (hfcʹs) of the nitrogen nuclei in the 15N-labeled radical cations of chlorophyll a and the primary donor P700 in photosystem I of spinach were investigated in frozen solution by two-dimensional stimulated echo ESEEM. 15N hfc tensors were evaluated by comparison of the experimental data with simulations of the time domain and frequency domain ESEEM signals. The results are discussed in the framework of a chlorophyll a dimer model for the radical cation of P700.