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Collisions of slow ions C3Hn+
and C3Dn+ (n = 2–8) with room temperature carbon surfaces: mass spectra of product ions and the ion survival
probability Andriy Pysanenko,a Jan Žabka,a Linda Feketeová,b Tilmann D. Märkb and
Zdenek Hermana,b,* aV. Čermák Laboratory, J. Heyrovský Institute of Physical Chemistry, v.v.i., Academy of Sciences of
the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic bInstitut für Ionenphysik und Angewandte Physik, Leopold-Franzens
Universität Innsbruck, Techniker Str. 25, 6020 Innsbruck, Austria
ABSTRACT:
Collisions of C3Hn+ (n = 2–8) ions and
some of their per-deuterated analogs with room temperature carbon (HOPG) surfaces (hydrocarbon-covered) were investigated over the incident energy range 13–45 eV
in beam scattering experiments. The mass spectra of product ions were measured and main fragmentation paths of the incident projectile ions, energized in the surface collision,
were determined. The extent of fragmentation increased with increasing incident energy. Mass spectra of even-electron ions C3H7+ and
C3H5+ showed only fragmentations, mass spectra of radical cations C3H8•+ and
C3H6•+ showed both simple fragmentations of the projectile ion and formation of products of its surface chemical reaction (H-atom
transfer between the projectile ion and hydrocarbons on the surface). No carbon-chain build-up reaction (formation of C4 hydrocarbons) was detected. The survival probability of
the incident ions, Sa, was usually found to be about 1–2% for the radical cation projectile ions C3H8•+,
C3H6•+, C3H4•+ and C3H2•+ and
several percent up to about 20% for the even-electron projectile ions C3H7+, C3H5+,
C3H3+. A plot of Sa values of C1, C2, C3, some C7 hydrocarbon ions, Ar+ and
CO2+ on hydrocarbon-covered carbon surfaces as a function of the ionization energies (IE) of the projectile species showed a drop from about
10% to about 1% and less at IE 8.5–9.5 eV and further decrease with increasing IE. A strong correlation was found between log Sa and
IE, a linear decrease over the entire range of IE investigated (7–16 eV), described by log Sa = (3.9 ± 0.5)–(0.39
± 0.04) IE.
Keywords:
ion-surface collisions, C3 hydrocarbon ions, carbon surface, fragmentation and surface reactions, ion survival probability
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