1,721,053 research outputs found
Effect of an Electric Field on the Optical Gap of Ge(111) 2 × 1 Surface States
No full textResults of electric field modulation of internal reflections in cleaved Ge(111) 2 × 1 surfaces are presented. They can be interpreted on the basis of a buckled model of the reconstructed surface with raised (lowered) atoms negatively (positively) charged. The value of the force constant for normal displacement of surface ions (1.1 × 105 dyn cm-1) is estimate
Optical detection of surface states on cleaved (111) surfaces of Ge
No full textOptical absorption of a cleaved surface of germanium shows a band at energies smaller than the gap, that is removed when the surface is oxidized. The band is assumed to be due to optical excitation of a surface state practically coincident with the top of the valence band to a set of states 0.16 eV below the bottom of the conduction band
Sviluppi nel Campo della Struttura Elettronica delle Superfici
No full textSi ripercorrono gli esperimenti importanti e gli sviluppi teorici e interpretativi nelo studio della struttura elettronica delle superfici e delle proprietà ottiche di superficie
Dissociation of Methane into Hydrocarbons at Extreme (Planetary) Pressure and Temperature
No full textConstant-pressure, first-principles molecular dynamic simulations were used to investigate the behavior of methane at high pressure and temperature. Contrary to the current interpretation of shock-wave experiments, the simulations suggest that, below 100 gigapascals, methane dissociates into a mixture of hydrocarbons, and it separates into hydrogen and carbon only above 300 gigapascals. The simulation conditions (100 to 300 gigapascals; 4000 to 5000 kelvin) were chosen to follow the isentrope in the middle ice layers of Neptune and Uranus. implications on the physics of these planets are discussed
THE EFFECT OF SURFACE-STATES AND BAND BENDING CHANGE ON REFLECTIVITY OF CLEAVED GAAS(110) AND GAP(110
No full textOptical absorption of surface states in ultrahigh vacuum cleaved (111) surfaces of Ge and Si
No full textThe optical absorption due to surface states on ultrahigh vacuum cleaved Ge and Si surfaces has been directly measured. Results show an absorption extending to energies lower than the edge, which disappears when the cleaved surfaces are oxidized. Possible optical transitions giving rise to this absorption are discussed. It is concluded that the dominant processes are transitions between two bands of surface states located in the gap. Combining the present results with photoelectric data, the energy position of the surface bands in Si is given
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
