Atomic layer deposition (ALD) can atomically tailor the shape and size of metal nanoparticles (NPs) during nucleation. If ultrathin metal films are desired, nucleation enhancement is crucial to obtain layer closure at low film thickness. However, state-of-the-art insights only offer information on the NP size and coverage in the late stages of nucleation, lacking fundamental knowledge on the initial nucleation density and atomic 3D structure of the nuclei in the very early stages of ALD growth, which inhibits nucleation control. In this proposal, our aim is to exploit the developed GIPDF methodology to uncover the role of different parameters which can influence and enhance ALD nucleation of Pt NPs, namely (1) surface pretreatment, (2) photo-assisted ALD, and (3) applying an ill-understood Pt(acac)2-O3 ALD process. By atomistic modelling of the GIPDF data, insights will be extracted which will guide controlled nucleation towards atomically tailored NPs or ultrathin metal films.