Conical octopole ion guide: Design, focusing, and its application to the deposition of low energetic clusters

Martin A. Röttgen, Ken Judai, Jean Marie Antonietti, Ueli Heiz, Stephan Rauschenbach, Klaus Kern

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

A design of a radio-frequency (rf) octopole ion guide with truncated conical rods arranged in a conical geometry is presented. The performance is tested in a cluster deposition apparatus used for the soft-landing of size-selected clusters on well-characterized substrates used as a model system in heterogeneous catalysis in ultrahigh vacuum. This device allows us to focus 500 pA of a mass-selected Ni20+ cluster ion beam from 9 mm down to a spot size of 2 mm in diameter. The transmittance is 70%±5% at a rf voltage of 420 Vpp applied over an amateur radio transceiver with an interposed homemade amplifier-transformer circuit. An increase of the cluster density by a factor of 15 has been achieved. Three ion trajectories are simulated by using SIMION6, which are relevant for this focusing device: transmitted, reflected, and absorbed. The observed effects in the simulations can be successfully explained by the adiabatic approximation. The focusing behavior of the conical octopole lens is demonstrated by experiment and simulations to be a very useful technique for increasing molecule or cluster densities on a substrate and thus reducing deposition time.

Original languageEnglish
Article number013302
Pages (from-to)1-6
Number of pages6
JournalReview of Scientific Instruments
Volume77
Issue number1
DOIs
StatePublished - 2006
Externally publishedYes

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