High energy ion beam analysis on polymers at cryogenic temperatures

We recently constructed a high energy ion scattering (HEIS) setup in which samples can be cooled to cryogenic temperatures to suppress ion beam induced damage in polymers. A closed cycle helium gas cooler provides the cooling power of 2 W at 10 K. The setup is equipped with a sample mount that enables sample exchange via a load lock system, while ensuring a good thermal contact with the sample holder by a shrink coupling. We investigated the effects of sample cooling on HEIS measurements on model polymer light emitting diodes and polyacrylate films. It can be concluded that hydrogen loss can be decreased from 50% to 10% for the same irradiation dose, and much more accurate depth profiling of elements is possible. (C) 2000 Elsevier Science B.V. All rights reserved.