Dr Matthew Bergin
School of Mathematical and Physical Sciences
- Doctor of Philosophy, University of Cambridge - UK
- Master of Natural Sciences, University of Cambridge - UK
- Bachelor of Arts, University of Cambridge - UK
- Master of Arts, University of Cambridge - UK
- Computational physics
- Mass spectrometry
- Scanning helium microscopy
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For publications that are currently unpublished or in-press, details are shown in italics.
Journal article (5 outputs)
Alkoby Y, Chadwick H, Godsi O, Labiad H, Bergin M, Cantin JT, et al., 'Setting benchmarks for modelling gas-surface interactions using coherent control of rotational orientation states', NATURE COMMUNICATIONS, 11 (2020)
Lambrick SM, Vozdecký L, Bergin M, Halpin JE, Maclaren DA, Dastoor PC, et al., 'Multiple scattering in scanning helium microscopy', Applied Physics Letters, 116 (2020) [C1]
Bergin M, Lambrick SM, Sleath H, Ward DJ, Ellis J, Jardine AP, 'Observation of diffraction contrast in scanning helium microscopy', SCIENTIFIC REPORTS, 10 (2020)
Bergin M, Ward DJ, Ellis J, Jardine AP, 'A method for constrained optimisation of the design of a scanning helium microscope', Ultramicroscopy, 207 (2019)
© 2019 Elsevier B.V. We describe a method for obtaining the optimal design of a normal incidence Scanning Helium Microscope (SHeM). Scanning helium microscopy is a recently develo... [more]
© 2019 Elsevier B.V. We describe a method for obtaining the optimal design of a normal incidence Scanning Helium Microscope (SHeM). Scanning helium microscopy is a recently developed technique that uses low energy neutral helium atoms as a probe to image the surface of a sample without causing damage. After estimating the variation of source brightness with nozzle size and pressure, we perform a constrained optimisation to determine the optimal geometry of the instrument (i.e. the geometry that maximises intensity) for a given target resolution. For an instrument using a pinhole to form the helium microprobe, the source and atom optics are separable and Lagrange multipliers are used to obtain an analytic expression for the optimal parameters. For an instrument using a zone plate as the focal element, the whole optical system must be considered and a numerical approach has been applied. Unlike previous numerical methods for optimisation, our approach provides insight into the effect and significance of each instrumental parameter, enabling an intuitive understanding of effect of the SHeM geometry. We show that for an instrument with a working distance of 1 mm, a zone plate with a minimum feature size of 25 nm becomes the advantageous focussing element if the desired beam standard deviation is below about 300 nm.
Lambrick SM, Bergin M, Jardine AP, Ward DJ, 'A ray tracing method for predicting contrast in neutral atom beam imaging', Micron, 113 61-68 (2018)
© 2018 The Authors A ray tracing method for predicting contrast in atom beam imaging is presented. Bespoke computational tools have been developed to simulate the classical trajec... [more]
© 2018 The Authors A ray tracing method for predicting contrast in atom beam imaging is presented. Bespoke computational tools have been developed to simulate the classical trajectories of atoms through the key elements of an atom beam microscope, as described using a triangulated surface mesh, using a combination of MATLAB and C code. These tools enable simulated images to be constructed that are directly analogous to the experimental images formed in a real microscope. It is then possible to understand which mechanisms contribute to contrast in images, with only a small number of base assumptions about the physics of the instrument. In particular, a key benefit of ray tracing is that multiple scattering effects can be included, which cannot be incorporated easily in analytic integral models. The approach has been applied to model the sample environment of the Cambridge scanning helium microscope (SHeM), a recently developed neutral atom pinhole microscope. We describe two applications; (i) understanding contrast and shadowing in images; and (ii) investigation of changes in image formation with pinhole-to-sample working distance. More generally the method has a broad range of potential applications with similar instruments, including understanding imaging from different sample topographies, refinement of a particular microscope geometry to enhance specific forms of contrast, and relating scattered intensity distributions to experimental measurements.
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