相关论文: Optical dichroism in nanotubes

Explicit expressions for the wave functions and dispersion equation for the band p - electrons in single-wall carbon nanotubes are obtained within the method of zero-range potentials. They are then used to investigate the absorption…

The circular dichroism (CD) spectra of single-wall carbon nanotubes are calculated using a dipole approximation. The calculated CD spectra show features that allow us to distinguish between nanotubes with different angles of chirality, and…

In quantum wires, such as metallic nanotubes, the optical absorption of the transverse polarization is controlled by the depolarization effect which stems from the redistribution of conduction electrons around the circumference of the…

Determination of optical absorption cross-section is always among the central importance of understanding a material. However its realization on individual nanostructures, such as carbon nanotubes, is experimentally challenging due to the…

We analyze optical absorption by atomically doped carbon nanotubes with a special focus on the frequency range close to the atomic transition frequency. We derive the optical absorbtion line-shape function and, having analyzed particular…

Light beams can be symmetric under different transformations: translations, rotations, mirror symmetries, duality transformations, etc. In this thesis, a systematic way of characterizing these symmetries is presented. Then, it is shown that…

We present results for the optical absorption spectra of small-diameter single-wall carbon and boron nitride nanotubes obtained by {\it ab initio} calculations in the framework of time-dependent density functional theory. We compare the…

We find exact conditions for the enhancement or suppression of internal and/or scattered fields and the determination of their spatial distribution or angular momentum through the combination of simple fields. The incident fields can be…

Circular dichroism is widely used for characterizing organic and biological materials, but measurements at a single molecule level are challenging because differences in absorption for opposite helicities are small. Here we show that…

We consider chirality related effects in optical, photogalvanic and electron-transport properties of carbon nanotubes. We show that these properties of chiral nanotubes are determined by terms in the electron effective Hamiltonian…

The high aspect ratio of carbon nanotubes makes them prone to bending. To know how bending affects the tubes is therefore crucial for tube identification and for electrical component design. Very few studies, however, have investigated…

Recent optical absorption/emission experiments showed that the lower energy optical transitions in carbon nanotubes are excitonic in nature, as predicted by theory. These experiments were based on the symmetry aspects of free electron-hole…

The theory of circular dichroism in single-wall carbon nanotubes derived within the tight-binding method by a complicated approach in previous work is rederived in a straightforward way using the multipolar expansion of the light-matter…

We investigate the properties of conduction electrons in single-walled armchair carbon nanotubes in the presence of mutually orthogonal electric and magnetic fields transverse to the tube's axis. We find that the fields give rise to an…

We report a combined electronic transport and structural characterization study of small carbon nanotube bundles in field-effect transistors (FET). The atomic structures of the bundles are determined by electron diffraction using an…

Band theory predicts an inverse square root van Hove singularity in the tunneling density of states at the minimum energy of an unoccupied subband in a one-dimensional quantum wire. With interactions, an orthogonality catastrophe analogous…

The full symmetry groups for all single- and multi-wall carbon nanotubes are found. As for the single-wall tubes, the symmetries form nonabelian nonsymorphic line groups, enlarging the groups reported in literature. In the multi-wall case,…

Various properties of the energy band structures (electronic, phonon, etc.), including systematic band degeneracy, sticking and extremes, following from the full line group symmetry of the single-wall carbon nanotubes are established. The…

The variation of the optical absorption of carbon nanotubes with their geometry has been a long standing question at the heart of both metrological and applicative issues, in particular because optical spectroscopy is one of the primary…

Physical property of a single quantum object is governed by its precise atomic arrangement. The direct correlation of localized physical properties with the atomic structures has been therefore strongly desired but still limited in the…