Scanning Transmission Ion Microscopy Time-of-Flight Spectroscopy Using 20 keV Helium Ions.

Scanning transmission ion microscopy imaging was performed whilst using a delay-line detector to record the impact position and arrival time of transmitted ions or neutrals. The incident helium ion beam had an energy of 20 keV and the arrival time measurements were used to calculate the energy loss after transmission through the sample. The 5D dataset thus produced (2D position in the sample plane, 2D position in the detector plane, and energy) is analyzed by collection into energy spectra or images.

Quantitative nanoscale imaging using transmission He ion channelling contrast: Proof-of-concept and application to study isolated crystalline defects.

A newly developed microscope prototype, namely npSCOPE, consisting of a Gas Field Ion Source (GFIS) column and a position sensitive Delay-line Detector (DLD) was used to perform Scanning Transmission Ion Microscopy (STIM) using keV He ions. One experiment used 25 keV ions and a second experiment used 30 keV ions. STIM imaging of a 50 nm thick free-standing gold membrane exhibited excellent contrast due to ion channelling and revealed rich microstructural features including isolated nanoscale twin bands which matched well with the contrast in the conventional ion-induced Secondary Electron (SE) imaging mode.

Scanning transmission imaging in the helium ion microscope using a microchannel plate with a delay line detector.

A detection system based on a microchannel plate with a delay line readout structure has been developed to perform scanning transmission ion microscopy (STIM) in the helium ion microscope (HIM). This system is an improvement over other existing approaches since it combines the information of the scanning beam position on the sample with the position (scattering angle) and time of the transmission events. Various imaging modes, such as bright field and dark field or the direct image of the transmitted signal, can be created by post-processing the collected STIM data.

Structural and chemical evolution of Au-silica core-shell nanoparticles during 20 keV helium ion irradiation: a comparison between experiment and simulation.

Au-silica core-shell nanoparticles have been irradiated with 20 keV He ions up to a maximum fluence of 4.7 × 10 ions/cm. The nanoscale structural and crystallographic evolution induced by He ion irradiation was followed at various stages using Transmission Electron Microscopy (TEM).

Stationary beam full-field transmission helium ion microscopy using sub-50 keV He: Projected images and intensity patterns.

A dedicated transmission helium ion microscope (THIM) for sub-50 keV helium has been constructed to investigate ion scattering processes and contrast mechanisms, aiding the development of new imaging and analysis modalities. Unlike a commercial helium ion microscope (HIM), the in-house built instrument allows full flexibility in experimental configuration. Here, we report projection imaging and intensity patterns obtained from powder and bulk crystalline samples using stationary broad-beam as well as convergent-beam illumination conditions in THIM.