Sample and plume luminescence in fast heavy ion induced desorption

Wilfried Tuszynski   Phone: +49-441-798-3203   Fax: +49-441-798-3201
Karten Koch   Phone: +49-441-798-3494   Fax: +49-441-798-3201
Eberhard R. Hilf   Phone: +49-441-798-2543   Fax: +49-441-798-3201

plumelumi.pdf (for internal use only!)
plumelumi.prep.pdf (Preprint)

Date: 1996

Article: published in Nuclear Instruments and Methods in Physics Research NIM B 107 (1996) p. 160

The luminescence arising in Cf 252-fission fragment induced desorption events
has been measured using the time-correlated single photon counting technique.
Photons emitted from the sample have been guided from a plasma desorption ion
source to a photodetector by an optical fibre. Spectra and decay functions have
been obtained using thin layers of Coronene or POPOP as samples. The results
are strongly dependent on the acceleration field applied for ion extraction.
Approximately 10 photons per fission fragment have been produced when applying
no accelerating voltage. The results clearly show that these photons come from
radiative electronic relaxations of molecules in the solid sample. Considerably
more photons per fission fragment have been produced when applying a positive
acceleration voltage. The intensity increases almost linearly for acceleration
fields below 10 kV/cm and saturates at a nearly 10-fold higher value when
compared to no  acceleration. The intensity is also affected by the homogeneity
of the accelerating field. These additional photons are attributed to radiative
electronic relaxations of desorbed neutral molecules in the plume excited by
inelastic collisions with accelerated positive ions. No additional photons have
been observed when extracting negative ions. The negative ions produced do
obviously not hit and/or excite desorbed neutral molecules, presumably due to
their specific desorption characteristics. The experimental data have been
analyzed by comparing with the cw and time-resolved sample luminescence
obtained by optical excitation.The findings demonstrate that valuable
information on ion-solid interactions, on specific desorption quantities and on
processes in the plume can be  obtained by measuring and analyzing the
luminescence induced by the impact of high energy primary ions.

DC-Metatags done by WUFI 1.1
Metadata by Thomas Severiens on 25 November 1998
Supporting work done by Sandra Valeska Bergmann.