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J. Schwestka, D. Melinc, R. Heller, A. Niggas, L. Leonhartsberger, H. Winter, S. Facsko, F. Aumayr, R. Wilhelm:
"A versatile ion beam spectrometer for studies of ion interaction with 2D materials";
Review of Scientific Instruments, 89 (2018), 0851011 - 0851018.

We present an ultrahigh vacuum setup for ion spectroscopy of freestanding two-dimensional solid targets.
An ion beam of different ion species (e.g., Xe with charge states from 1 to 44 and Ar with
charge states from 1 to 18) and kinetic energies ranging from a few 10 eV to 400 keV is produced
in an electron beam ion source. Ions are detected after their transmission through the 2D
target with a position sensitive microchannel plate detector allowing the determination of the ion´s
exit charge state as well as the scattering angle with a resolution of approximately 0.04!. Furthermore,
the spectrometer is mounted on a swiveling frame covering a scattering angle of ±8! with
respect to the incoming beam direction. By utilizing a beam chopper, we measure the time-offlight
of the projectiles and determine the energy loss when passing a 2D target with an energy
uncertainty of about 2%. Additional detectors are mounted close to the target to observe emitted
secondary particles and are read-out in coincidence with the position and time information of the
ion detector. A signal in these detectors can also be used as a start trigger for time-of-flight measurements,
which then yield an energy resolution of 1% and an approximately 1000-fold larger
duty cycle. First results on the interaction of slow Xe30+ ions with a freestanding single layer of
graphene obtained with the new setup are compared to recently published data where charge exchange
and energy were measured by means of an electrostatic analyzer.