Direct imaging of nanoparticle embedding into PS films

Non-contact Atomic Force Microscopy (AFM) was used to study the embedding of 10 nm and 20 nm gold nano-particlcs into the surface of polystyrene films spin-coated onto silicon substrates. The rate of embedding was determined by measuring the apparent nanosphere height as a function of annealing time. This was accomplished by two different methods. In the first case, each image (after a specific annealing time) is acquired at a different spot on the sample surface. In this case a fairly large (∼40) number of particles were imaged in order to have acceptable statistics. A second method involved the use of a kinematic mounting hot stage that allowed the same spot on the sample to be imaged at each time. This allows the same final precision without the same necessity for imaging large numbers of particles. The results indicate that sub nm resolution is easily obtainable with either technique.