Suppression and enhancement of secondary ion formation due to the chemical environment in static-secondary ion mass spectrometry.
Through analyzing mixtures of compounds of known gas-phase basicities, the importance of this property on the secondary ions emitted from a surface under primary ion bombardment is investigated. The aim is to obtain a greater understanding of the ionization mechanisms that occur in secondary ion mass spectrometry (SIMS). The commonly used matrix assisted laser desorption/ionization (MALDI) matrix 2,4,6-trihydroxyacetophenone (THAP) and a range of low molecular weight biomolecules were used to investigate whether analyte/matrix suppression effects that have been observed in analogous MALDI experiments were also present in static-SIMS. The outcome of the experiments demonstrates that strong suppression of the quasi-molecular signal of one molecule in a mixture can occur due to the presence of the other, with the gas-phase basicity of the compounds being a good indicator of the secondary ions detected. It is also demonstrated that the suppression of the quasi-molecular ion signal of a compound in a two-component mixture can be minimized by the inclusion of a third compound of suitable gas-phase basicity.
Jones
Emrys A
EA
Surface Analysis Research Centre, Manchester Interdisciplinary Biocentre, CEAS, University of Manchester, Manchester, United Kingdom. emrys.jones@manchester.ac.uk
Lockyer
Nicholas P
NP
Kordys
Jeanette
J
Vickerman
John C
JC
D000098:Acetophenones / Q000737:chemistry*; D001463:Barbiturates / Q000737:chemistry; D003596:Cytosine / Q000737:chemistry; D008956:Models, Chemical; D009842:Oligopeptides / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D013941:Thymine / Q000737:chemistry
D000098:Acetophenones; D001463:Barbiturates; D009842:Oligopeptides; C037026:diglycyl-histidine; D003596:Cytosine; C107067:2,4,6-trihydroxyacetophenone; D013941:Thymine; C032232:barbituric acid