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High-sensitivity and high-resolution low-energy ion scattering |
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| Authors: | Hidde H. Brongersma Thomas Grehl Niels C.W. Kuijpers Emma R. Schofield Hendrik R.J. ter Veen |
| Affiliation: | a Calipso B.V., P.O. Box 513, 5600 MB Eindhoven, The Netherlands b ION-TOF GmbH, Heisenbergstr. 15, 48149 Münster, Germany c Johnson Matthey Technology Centre, Blount's Court Road, Sonning Common, Reading RG4 9NH, United Kingdom d Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands e Tascon GmbH, Heisenbergstr. 15, 48149 Münster, Germany |
| Abstract: | Low-Energy Ion Scattering (LEIS or ISS) is used to selectively analyze the atomic composition of the outer atomic layer of surfaces. In addition, the spectrum gives (non-destructively) the in-depth distribution. Using a double toroidal energy analyzer with parallel energy detection and time-of-flight filtering a high sensitivity and mass resolution of LEIS is achieved. This is demonstrated for a highly dispersed catalyst of Pt/Au on γ-alumina. The improved depth resolution is illustrated for self-assembled monolayers of alkanethiols (12-20 carbon atoms) on gold. Even for these low Z carbon atoms a clear shift of 8 eV/carbon atom is observed (using 1.5 keV 4He+ ion scattering). This opens many new possibilities for studies of ultra-thin diffusion barriers, high-k dielectrics and biosensors. |
| Keywords: | LEIS High sensitivity Mass resolution Depth resolution Self-assembled monolayer Quantitative |
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