Nature of the Electron‐Hole Pair in the System Anthracene Crystal/Rhodamine B Adsorbed from Aqueous Solution Part II: Dependence of Kinetics and Spin‐Dynamics on Shallow Surface Traps

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Abstract
The dependence of the rhodamine B sensitized hole current (SHC) and of its magnetic field modulation (ΔSHC) on the applied electric field has been measured in anthracene single crystals with different concentrations of shallow surface traps. Our theoretical model for the influence of the magnetic hyperfine effect (HF effect) on the charge carrier kinetics has been extended to account for the effect of shallow traps. The model predicts in agreement with the experimental finding as effect of shallow surface traps, firstly an increase in the magnitude and secondly an increase in the halfwidth of the magnetic field modulation of the SHC, and thirdly a weakened influence of the electric field on these two signals. The smallest concentration of shallow surface traps was found on naturally grown surfaces of sublimation crystals, whereas solution grown crystals showed in general a higher concentration of such traps. It was found that shallow hole traps can be induced with carbazol molecules.