This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The angular distribution of hydrogen scattered from a (100) oriented tungsten crystal has been measured at room temperature for both the clean surface and the hydrogen-covered surface. Of the molecules incident on the clean surface, 81% were chemisorbed, 16% were scattered diffusely according to the cosine law, and 1% were specularly reflected. The remaining 2% appeared in a secondary peak, the origin of which is not fully understood. Scattering from the hydrogen-covered surface was dominated by an intense specular reflection. Diffraction was also observed and eight first-order diffraction peaks were identified.