Microscope mode secondary ion mass spectrometry imaging with a Timepix detector

Abstract

In-vacuum active pixel detectors enable high sensitivity, highly parallel time-and space-resolved detection of ions from complex surfaces. For the first time, a Timepix detector assembly was combined with a secondary ion mass spectrometer for microscope mode secondary ion mass spectrometry (SIMS) imaging. Time resolved images from various benchmark samples demonstrate the imaging capabilities of the detector system. The main advantages of the active pixel detector are the higher signal-to-noise ratio and parallel acquisition of arrival time and position. Microscope mode SIMS imaging of biomolecules is demonstrated from tissue sections with the Timepix detector.

Modifications to a commercially available linear mass spectrometer for mass‐resolved microscopy with the pixel imaging mass spectrometry (PImMS) camera

“…Ionising beams must be defocused yet remain homogeneous, while detectors must have high spatial, and temporal resolutions. An MCP‐scintillator detector coupled with a framing CCD camera can achieve high spatial resolutions but more recently time‐stamping pixel cameras and delay line detectors have been developed which can acquire images for multiple m/z ranges simultaneously . The introduction of this multi‐mass imaging technology means that a microscope‐mode experiment no longer needs to involve scanning over the m/z coordinate giving a further marked decrease in acquisition time.…”

Chemical Imaging

“…during the analysis of degrading (biological) samples. 55 However, to gather statistically valid counts for masses with low count rates, extended counting times per pixel might be required. 56 Also for images acquired at the highest spatial resolution, even small amounts of specimen or stage drift can lead to blurring of the image.…”

“…56 To improve the imaging process in the microscope mode by higher signal-to-noise ratio and parallel acquisition of arrival time and position, active pixel detectors (see Section 4.12) have been developed and applied. 25,55,57 During ''scanning ion imaging'' an ion beam is directed over the sample surface in a defined raster pattern, while software saves secondary ion intensities as a function of beam position from which maps of secondary ion images are generated. 10,13 The image shape follows the raster pattern shape, which is the reason that these images are usually square.…”

Experimental Investigation of the 2D Ion Beam Profile Generated by an ESI Octopole-QMS System

“…Previously, the use of the Timepix detector with other MS technologies such as secondary ion mass spectrometry (SIMS) [21] and a TOF instrument [22,23] has been demonstrated for MSI with a spatial resolution of few micrometers. In this paper, the implementation of a Timepix detector system on a QMS with a cooling octopole ion guide is presented.…”