Evolution of energy deposition processes in anthracene single crystal from photochemistry to radiation chemistry under excitation with synchrotron radiation from 3 to 700 eV

Absolute values of quantum yield Φ(hν) of singlet exciton formation in anthracene single crystals were measured as a function of photon energy hν, with the usage of synchrotron radiation (SR) in 3–700 eV region. Values of Φ(hν) were found to increase linearly for hν⩾75 eV. For hν⩽40 eV, values of Φ(hν) gave a wealth of structures and are not linear to hν. Because number of secondary electrons produced by radiation is thought to increase in proportional to the incident photon energy, it is natural to conclude that the radiation chemistry effect becomes dominant above 75 eV. On the other hand, values of Φ(hν) showed response due to resonance rather than linear dependence with hν, which implies that the photochemical effect is dominant below 40 eV.