Neutral Ytterbium (YbI) and singly ionized Ytterbium (YbII) is widely used in experiments in quantum optics, metrology and quantum information science. We report on the investigation of isotope selective two-photoionisation of YbI that allows for eff
icient loading of ion traps with YbII. Results are presented on two-colour (399 nm and 369 nm) and single-colour (399 nm) photoionisation and their efficiency is compared to electron impact ionisation. Nearly deterministic loading of a desired number of YbII ions into a linear Paul trap is demonstrated.
