We show that reflection of a monochromatic light from a semi-infinite medium covered with a stack of layered media is equivalent to that from an effective "semi-infinite medium" characterized by two distinctive optical dielectric constants for the s-polarized and p-polarized components, respectively. Such an effective-substrate approach simplifies the analysis of ellipsometry measurements of a wide range of surface-bound processes including thin film growth and surface-bound reactions.

We formed grating-like patterns of hydrogen adatom density on Cu(111) by using complementary patterns of xenon adatom density as the template. The template was preformed by laser-induced thermal desorption of a Xe monolayer on Cu(111) using the interference pattern of two coherent laser pulses. By following the evolution of hydrogen density gratings on Cu(111) from 153 to 183 K with linear optical diffraction, we found that the diffusion of hydrogen atoms on Cu(111) in this temperature range is the classical over-barrier hopping characterized by an activation energy barrier E diff = 6.4 Kcal/mol (or 279 meV) and a pre-exponential factor D0 = 2.0×10 −3 cm 2 /s. Based on the potential model proposed by Basdescu and coworkers for hydrogen on Ni(111), the WKB tunneling coefficient between the first vibrational excited states of a hydrogen adatom on Cu(111) is expected to be at least one order of magnitude smaller than that on Ni(111), indicating that the classical over-barrier hopping of hydrogen atoms could directly cross over to under-barrier tunneling between ground states on Cu(111).

No abstract

We excited surface-plasmon polariton waves (SPPWs) on Cu(111) by coupling optical beams with adsorbed xenon gratings. The SPPWs's excitation causes a resonancelike dip in the angle-resolved reflectivity difference measurement. From the resonance we determined optical constants epsilonCu(633 nm)=-9.53+i0.142 and epsilonCu(780 nm)=-13.44+i0.18. The grating-coupled SPPWs can be used to study mass transport on thin films.

No abstract