Cryogenic Honey Droplet Preparation

As sample material, natural honey from the company Langnese was used. Tungsten wires were used as substrate material and their rough surfaces were produced by applying a tensile force under cryogenic conditions^{43 (link),44 (link),66 (link)}. It’s well known that honey has a high viscosity and, therefore, sticks to different surfaces. In the case of honey, the rough tungsten wire, was initially dipped into the honey and afterwards quenched to cryogenic temperature into a liquid N₂ bath. The obtained honey droplet with a diameter of 50 µm can be seen in Fig. 9B. This method cannot be used for low viscous liquids; therefore, a dedicated method was developed as reported in^{43 (link),44 (link),66 (link)}. After that, the sample holder was transferred as fast as possible into the body of the cooled transfer shuttle VCT500 from Leica (T = − 184 °C). This system allowed to transfer of samples at cryo-temperatures (T = − 184 °C) and under a low-pressure atmosphere (10^–4 mbar) between the machines without contaminations from the environment.Figure 9

FIB Preparation—above in (A) the annular milling process with a decreasing inner diameter and respective current is schematically shown. (B) Frozen honey droplet on top of the tungsten post. (A–I) show the milling process with an annular pattern and decreasing inner diameter until a final tip with a radius < 100–200 nm (J) is obtained.