Scattering of N sub 2 from Ni(111)

• Published in: Surface science 2000-07, Vol.460 (1-3), p.12-20
• Main Authors: Zare, R N, Balzer, F, Hallock, A J, Ellison, M D, Matthews, C M
• Format: Article
• Language: English
• ISSN: 0039-6028

A cold (T sub rot < 10 K) beam of N sub 2 with an initial translational energy of 0.40 eV strikes an Ni(111) surface at surface temperatures from 300 to 873 K at several incident angles from 15 to 60 deg . The rotational energy and angular distributions of the scattered molecules are probed using (2 + 1) resonance-enhanced multiphoton ionization. Molecules scattered in the specular direction have mean rotational energies that are independent of surface temperature, whereas those scattered at angles far from the specular show a dependence on surface temperature, caused likely by multiple collisions with the surface before escape. A rotational rainbow, seen in systems such as CO-Ni(111) and N sub 2 -Ag(111), is not seen in this system. For molecules that scatter close to the specular direction, approximately 10% of the initial translational energy is converted into rotational energy of the scattered N sub 2 . For surface temperatures above room temperature, the angular distributions indicate that molecules that scatter into low-J states also tend to exit in a broad peak (10-20 deg FWHM) near the specular, and this peak is broadened with increasing incident angle. The molecules that scatter into high-J states have a much broader distribution, indicating that they are trapped rotationally during the initial collision and suffer multiple collisions before leaving the surface.