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|Title:||Communication: the formation of helium cluster cations following the ionization of helium nanodroplets: influence of droplet size and dopant.|
Ellis, Andrew M.
|Publisher:||American Institute of Physics (AIP)|
|Citation:||Journal of Chemical Physics, 2011, 135 (4), 1101 (4).|
|Abstract:||The He(n)(+)/He(2)(+) (n ≥ 3) signal ratios in the mass spectra derived from electron impact ionization of pure helium nanodroplets are shown to increase with droplet size, reaching an asymptotic limit at an average droplet size of approximately 50,000 helium atoms. This is explained in terms of a charge hopping model, where on average the positive charge is able to penetrate more deeply into the liquid helium as the droplet size increases. The deeper the point where the charge localizes to form He(2)(+), the greater the likelihood of collisions with the surrounding helium as the ion begins to leave the droplet, thus increasing the probability that helium will be ejected in the form of He(n)(+) (n ≥ 3) cluster ions rather than He(2)(+). The addition of a dopant alters the He(n)(+)/He(2)(+) ratio for small helium droplets, an observation attributed to the potential energy gradient created by the cation-dopant interaction and its effect in drawing the positive charge towards the dopant in the interior of the droplet.|
|Rights:||Copyright 2011 American Institute of Physics. Deposited with reference to the publisher's archiving policy available on the SHERPA/RoMEO website. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Chemical Physics, 2011, 135 (4), pp. 41101-41101 and may be found at http://jcp.aip.org/resource/1/jcpsa6/v135/i4/p041101_s1.|
|Appears in Collections:||Published Articles, Dept. of Chemistry|
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