Theoretical and Experimental Optical Spectroscopy Study of Hydrogen Adsorption at Si(111)-(7×7)

Site-Sensitive Gas Sensing and Analyte Discrimination in Langmuir−Blodgett Porphyrin Films

“…In this sense, the The Journal of Physical Chemistry C ARTICLE information delivered from RAS, although averaged in the macroscopic region covered by the light spot, allows an insight in the microscopic structure of the system: if a particular spectral feature, associated to particular sites or bonds at the layer, disappears or modifies after the organic layer has been exposed to a vapor, the preferential adsorption of the analyte to that site or bond can be reasonably inferred. 24 In Figure 2 we compare the RAS spectra for the 8 MLs thick LB film before and after the activated sample has been exposed to (respectively) hexane (18%, corresponding to 27 180 ppm, curve a), ethanol (18%, corresponding to 10 656 ppm, curve b), and butylamine (1%, 1475 ppm, curve c) vapors. These dilution values (corresponding to different concentrations) have been chosen to gain a well detectable RAS signal level: for butylamine a low concentration has been used, because this analyte strongly interacts with the porphyrin, producing sometime irreversible modifications in the spectra.…”

In situ differential reflectance spectroscopy study of solid phase epitaxy in Si(111)-Fe and Si(111)-Cr systems

“…Both described MDS and MOS are used to treat DRS data obtained during RDE [2,3] or MBE [8,9]. They can be used for initial stage of SPE (RT deposition, Fig.…”

Reflectance Anisotropy of GaAs(100): Theory and Experiment

“…We calculate the optical properties by the sp 3 s ‫ء‬ tightbinding approach, which has proven successful for a number of homopolar surfaces [10][11][12]. To separate the contributions of the two opposite surfaces, which yield different optical properties, a linear cutoff function was used in calculating the optical matrix elements.…”

“…Hence, using a reliable theoretical description it should be possible to relate the optical response to the atomic surface structure. At present, few examples of good agreement between experiments and calculations of the optical response based on the one-electron band structure approximation, employing semiempirical tight-binding [10][11][12] as well as ab initio plane-wave expansions [13], are available. For GaAs(100), however, theoretical results are rather unsatisfactory [14,15], and recently it was hypothesized that RAS line shapes in many cases may have little to do with the atomic structure of the surface, but are rather determined by surface-induced changes of excitonic and local-field effects on bulk transitions [16,17] which are not included in the above mentioned calculations.…”