Low energy acetone dimer ion/surface collisions studied with high energy resolution

Abstract

We have recently constructed the tandem mass spectrometer set-up BESTOF (consisting of a B-sector field combined with an E-sector field, a Surface and a Time Of Flight mass spectrometer) which allows the investigation of ion/surface reactions with high primary mass and energy resolution. Using BE-STOF we have extended previous investigations from molecular projectile ions to cluster ions. In particular, we have studied here surface induced dissociation (SID) and surface induced reactions (SIR) of acetone dimer ions upon impact on a hydrocarbon covered stainless steel surface as a function of incident collision energy up to about 80 eV.PACS. 34.90.+q Other topics in atomic and molecular collision processes and interactions -82.65.Fr Film and membrane processes: ion exchange, dialyse, osmosis, electroosmosis -82.30.Fi Ion-molecule, ion-ion, and charge transfer reactions

Surface-induced reactions of polyatomic ions and cluster ions

“…As discussed above, surface reactions of the acetone monomer cation gives as a major product ion the protonated acetone ion formed exclusively by H abstraction from hydrocarbons chemisorbed on the surface (reaction ( 6)). As shown in figure 12, this protonated acetone ion is also the most prominent reaction product from the surface reaction of acetone dimer ions (and also for higher cluster analogues discussed in [23,44]). Thus in line with the aforementioned it is conceivable that in principle this ion may be produced by two competing reactions by the impacting dimer ion, i.e.,…”

“…The results obtained corroborate measurements carried out in collaboration with Winter and co-workers [26][27][28] on the electron number statistics (from which total electron yields have been derived) for the impact of slow multiply charged fullerene ions on an atomically clean polycrystalline gold surface showing as the most surprising result a complete suppression of potential electron emission. Finally, we have obtained also for the first time experimental evidence for intracluster reactions initiated upon (hydrocarbon-covered stainless steel) surface impact [23], i.e., a process in which for instance collisions of size-selected unprotonated acetone cluster ions A + n (with A for acetone) with a hydrocarbon covered stainless steel surface lead-besides to typical fragmentation patterns A + , A + 2 , . .…”

“…Nevertheless, in the present investigation we will only concentrate on the interaction of the stoichiometric cluster ion (in particular the dimer ion) with the stainless steel surface. For further results see forthcoming papers from our laboratory [23,44].…”

“…In order to rationalize the occurrence of these reaction products for the interaction of the acetone dimer ion with the surface, we have to assume that the hydrogenbonded dimer ion may alternatively exist before the impact in two different isomeric configurations separated by a small barrier (for details see [23]), i.e., one consisting of (CD 3 COCD 2 )(CD 3 COCD 3 )D + and one consisting of (CD 3 COCD 3 )(CD 3 COCD 3 ) + . As discussed above surface collisions convert translational energy very efficiently into internal energy.…”

“…In a recent effort to improve this situation we have constructed the tandem mass spectrometer set-up BESTOF (consisting of a B-sector field combined with an E-sector field, a surface and a time of flight mass spectrometer) [11,[19][20][21][22][23][24][25] which allows the investigation of ion/surface reactions with high primary mass and energy resolution, i.e., energy spreads of as low as 80 meV fwhm have been achieved. Using BESTOF we have extended previous investigations in several respects [11,[19][20][21][22][23][24][25]. Firstly, we have revisited previously investigated surface induced reactions of various polyatomic ions including the acetone ion [19], the benzene ion [21] and CF + 3 [22] interacting with stainless steel surfaces.…”