  There has been an increasing interest in atom probe tomography (APT) to
characterise hydrated and biological materials. A major benefit of APT compared
to microscopy techniques more commonly used in biology is its combination of
outstanding 3D spatial resolution (~0.2 nm) and mass sensitivity. APT has
already been successfully used to characterise biological materials, revealing
key structural information at the atomic scale, however there are many
challenges inherent to the analysis of hydrated materials. New preparation
protocols, often involving sample preparation and transfer at cryogenic
temperature, enable APT analysis of hydrated materials and have the potential
to enable 3D atomic scale characterisation of biological materials in the
near-native hydrated state. In this study, APT specimens of pure water at the
tips of tungsten needles were prepared at room temperature by graphene
encapsulation. A parametric study was conducted where samples were transferred
at either room temperature or cryo-temperature and analysed by APT by varying
parameters such as the flight path and pulsing mode. The differences between
the acquisition scenarios are presented along with recommendations for future
studies.
