The dynamics of nanoparticle formation by laser ablation into background gases are revealed by gated-ICCD photography of photoluminescence (PL) and Rayleigh-scattering (RS) from gas-suspended nanoparticles. These techniques, along with gated-spectroscopy of PL from isolated, gassuspended nanoparticles, permit fundamental investigations of nanomaterial growth, doping, and luminescence properties prior to deposition for thin films. Using the time-resolved diagnostics, particles unambiguously formed in the gas phase were collected on TEM grids. Silicon nanoparticles, 1-10 nm in diameter, were deposited following laser ablation into 1-10 TorrAror He. Three in situ PL bands (1.8, 2.6, 3.2 eV) similar to oxidized porous silicon were measured, but with a pronounced vibronic structure. Structureless photoluminescence bands were reproduced in the films (2.1, 2.7, 3.2 eV) only after standared annealing. The ablation of metal zinc into Ar/02 is also reported for the preparation of < 10 nm diameter hexagonal zincite nanocrystals, The particles were analyzed by bright field and Z-contrast TEM and high resolution EELS.