The Interaction Of Monatomic And Diatomic Molecules With Solid Surfaces The Structure Of Water Cluster Beams And Their Scattering From Surfaces

Download or read book The Interaction of Monatomic and Diatomic Molecules with Solid Surfaces: The Structure of Water Cluster Beams and Their Scattering from Surfaces written by David D. Dreyfuss and published by . This book was released on 1980 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of homogeneous and heterogeneous nucleation was conducted, using molecular beam techniques: mass spectrometry and time-of-flight velocity spectrometry, with and without mass filtering. Both the clustered beam itself and the scattering of the clusters from surfaces were studied. The beam was found to consist of a broad spectrum of clusters all having approximately the same velocity distribution. Small clusters were found to have a binding energy much less than that of bulk ice. Measurements of a beam scattered from a surface using a time-of-flight velocity spectrometer show four distinct patterns. These are: (1) a diffuse scattering channel (monomers, Maxwellian/cosine at the target temperature), (2) a direct inelastic channel for monomers characterized by a small loss of incident velocity with a broad spatial distribution peaked at the tangent for all incident angles, theta sub i, (3) a well-defined specular directed lobe (theta sub s = theta sub i greater than 50 deg) with particle velocity much slower than (1) or (2) and a velocity distribution narrower than a stationary Maxwellian, and (4) another slow peak with a slightly broader velocity distribution into a sharp intensity peak near the tangent for all theta sub i greater than 50 deg. The amplitude of the specularly directed slow peak (3) appears to give a sensitive indication of surface coverage. (Author).