Prospect of increasing secondary ion yields in ToF-SIMS using water cluster primary ion beams
Journal article, 2014

Low ionization yields in time of flight secondary ion mass spectrometry (ToF-SIMS) particularly from single cells and tissues are proving to be a significant limitation in allowing this technique to reach its full potential. A number of approaches including embedding the sample in water or spraying water above sample surface has shown great prospective for increasing the ionization yield by a factor of 10 to 100 through proton mediated' reaction. Based on this hypothesis, a water cluster primary ion source has been developed in collaboration with Ionoptika Ltd to generate giant water cluster ions (H2O)(n)(+) (n=1-10000) using a similar supersonic jet expansion methodology as for argon cluster beams. The ion yields of arginine, cholesterol, angiotensin II and a lipid mix have been measured under static and high ion dose conditions using (H2O)(5000)(+), (H2O)(3000)(+), Ar-3000(+) and C-60(+) primary ion beams at 20keV. An enhancement in yields up to a factor of around 4 is observed under water cluster impact, in comparison with C-60(+) at 1x10(11)ions/cm(2) ion dose, whereas this increases by around 10-50 times at high ion dose conditions. Copyright (c) 2014 John Wiley & Sons, Ltd.



amino acids



ionization yields

water cluster beams




S. Sheraz

A. Barber

I. B. Razo

John Fletcher

University of Gothenburg

N. P. Lockyer

J. C. Vickerman

Surface and Interface Analysis

0142-2421 (ISSN) 1096-9918 (eISSN)

Vol. 46 51-53

Subject Categories

Physical Chemistry

Materials Chemistry



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