While XUHV is beneficial, it comes with its own set of challenges:
Outgassing: Even at XUHV, materials can outgas, releasing molecules into the vacuum. This is particularly problematic for organic materials. System Leaks: Ensuring that there are no leaks in the system is critical. Even the smallest leak can significantly degrade the vacuum quality. Measurement Accuracy: Measuring pressure at such low levels requires highly sensitive and accurate gauges, such as Ionization Gauges.