Using in-situ during-process single wavelength ellipsometry, the interaction of a Te-2 molecular beam with a dehydrogenated Si(013) surface has been studied for a wide range of deposition conditions. Almost every possible nucleation and growth behavior can be observed and ellipsometrically discriminated in this substrate-layer combination. Under favorable circumstances some relevant parameters of the deposit, such as island size and density, can be extracted directly from the system's trajectory in the Psi-Delta plane.