Patent ID: 8274042
Filing Date: 2012-09-25
Classification: H01J

Abstract:
1. A method for measuring spatial distribution of a single species of analyte molecules on or in a two-dimensional sample in a time-of-flight mass spectrometer with a reflector and a detector, the method comprising: (a) ionizing at least some of the analyte molecules from one point on the sample to provide molecular ions, and accelerating the molecular ions; (b) decomposing at least some of the molecular ions into daughter ions; (c) selecting a species of the molecular ions of the single species of analyte molecules and corresponding daughter ions of the selected molecular ions with an ion selector, wherein the molecular weight of the selected molecular ions is below 1000 Daltons, and directing substantially all of the selected species of the molecular ions and the corresponding daughter ions from the ion selector to the reflector wherein the selected species of the molecular ions and the corresponding daughter ions are not substantially accelerated between the ion selector and the reflector; (d) adjusting the reflector to a voltage setting that is optimal for one selected species of the corresponding daughter ions, and directing the selected species of daughter ions onto the detector, and measuring a daughter ion single spectrum of the selected species of daughter ions at the detector; (e) repeating steps (a) to (d) at the same point on the sample, and combining the daughter ion single spectra of this location to form a sum spectrum; (f) repeating steps (a) to (e) at different points on the sample; and (g) measuring the spatial distribution of the single species of analyte molecules by obtaining signal strengths of the one selected species of daughter ions at the individual locations on the sample from the sum spectra.