Luminescence in thin molecular samples by bombardment with single MeV atomic ions

The luminescence induced by the bombardment of thin molecular samples with single MeV atomic ions has been measured by time-correlated single photon c ounting. The MeV-energy ions (Z = 6...79) were produced at the Erlangen tan dem accelerator. The samples were layers of POPOP or CsI deposited on a thi n polyester foil at a thickness which allows the ions to traverse the sampl es. The relative photon yield has been found to be proportional to the ener gy density along the ion trajectory when the initial velocity is kept const ant. When the initial velocity of the primary ion was varied, a distinct ma ximum of the photon yield has been found which is clearly shifted to higher energies compared to the energy of the Bragg maximum. By means of calculat ions based on the energy deposition of the secondary electrons it was found that the observed luminescence is only produced in the region of low energ y density at larger radial distances from the ion track. (C) 1998 Elsevier Science B.V. All rights reserved.