Abstracts » Chemicals, plastics and rubber industries

Screening and surface states in molecular monolayers adsorbed on silicon

Article Abstract:

Density functional theory (DFT) calculations were used to study the atomic and electronic structure of several different interfaces between the Si(100) surface and a dense monolayer of a model molecule composed by a long alkyl chain and a phenyl head. Evidence for a strong effect of intermolecular screening of the electrostatic interaction was found and the major result of such screening was the reduction of the ionization potential and electronic affinity.

Monomolecular films, Density functionals, Density functional theory

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Elucidating Si-Si dimmer vibration from the size-dependant Raman shift of nanosolid Si

Article Abstract:

With the solid size reduction, the transverse optical (TO) Raman mode shifts to lower frequency and new low-frequency Raman (LFR) acoustic modes are generated and shift to higher frequency upon nanosolid Si formation. On the basis of bond-order-length-strength correlation, TO red shift arises from the cohesive bond weakening of the lower coordinated atoms near the surface region of the nanograin, and the LFR arises from intergrain interaction.

Analysis, Raman effect

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Carrier relaxation and lattice heating dynamics in silicon revealed by femtosecond electron diffraction

Article Abstract:

Femtosecond electron diffraction is used to resolve the dynamics of electron-phonon relaxation in silicon. The results have shown that the relaxation time constant is consistent with the excitation regime where the phonon emission rate is reduced due to carrier screening.

Science & research, Research, Lattice dynamics, Electrons, Electron diffraction

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