HEAVY PARTICLE INDUCED ION EMISSION FROM LANGMUIR-BLODGETT-FILMS - DEPENDENCE ON THE CHARGE STATE AND THE ANGLE OF INCIDENCE

At the Orsay tandem accelerator beams of S-32 and I-127 at energies of 1 MeV/u were used to investigate secondary ion emission from Langmuir-Blodgett films deposited an Au. The yields of negative parent ions, dimer and trimer ions were measured for various superposed fatty acid layers as function of primary ion charge state and angle of incidence. By means of TOF mass spectrometry the ejection of intact molecular ions was observed from layers as deep as 200 angstrom underneath the surface. For grazing primary ion trajectories, the charge state dependence of yields are almost independent of the charge state of the primary ions (PI). The results are in fair agreement with theoretical calculations based on crater formation due to a shock wave expanding from the highly energized zone along the nuclear track.