Surface induced ionization of neutral water clusters

Ionization of water clusters by collisions with graphite surfaces

“…Based on these results we conclude that large cluster fragments can survive the surface interaction still maintaining a kinetic energy of up to 100 eV, and may leave the surface positively or negatively charged. This conclusion is in agreement with the previous results by Vostrikov et al [9][10][11] on water cluster scattering from different surfaces. If we assume that a cluster can not gain kinetic energy during the surface collision, a final kinetic energy of 100 eV corresponds to a final cluster size n = 625.…”

“…We have recently used molecular dynamics simulations to show that this mechanism makes large cluster fragments survive surface scattering of Ar n from Pt(111) [27]. The mechanism is also supported by surface scattering experiments with van der Waals clusters [12][13][14] and water clusters [9][10][11]. Experimental angular distributions show that the scattered flux of large fragments is forced towards the tangential direction, indicating that energy is taken from the normal component while the parallel component is essentially conserved.…”

“…Vostrikov et al [9][10][11] determined an ionization probability of 10 −4 in surface scattering of water clusters with an average cluster sizen = 1500. The experimental results presented in this study indicate that the ionization probability should be comparable, although absolute values have not been determined.…”

“…It was heatable up to 1500 K by a DC current (0-40 A) through the sample, and its temperature was determined by corrected pyrometer readings. The angle between the incident beam and the surface normal was fixed at 70 • , and this choice was motivated by the maximum in ionization efficiency observed by Vostrikov et al for large incident angles [9][10][11]. Ions emitted from the surface were measured with a cylindrical collector that was mounted around the graphite sample, with the sample situated in the center of the cylinder.…”

“…Christen et al [8] investigated scattering of SO 2 clusters from different surfaces and found emissions of both negative and positive ions. Vostrikov and coworkers [9][10][11] investigated scattering of neutral water clusters with 1300 m/s from different surfaces, and detected both positive and negative cluster ions in the scattered flux. The ion intensity showed a strong dependence on incident scattering angle θ i , with a maximum at θ i = 70±5 • .…”