Coherent control of photocurrents in graphene and carbon nanotubes
نویسندگان
چکیده
Coherent one-photon (2v) and two-photon (v) electronic excitations are studied for graphene sheets and for carbon nanotubes using a long-wavelength theory for the low-energy electronic states. For graphene sheets we find that a coherent superposition of these excitations produces a polar asymmetry in the momentum space distribution of the excited carriers with an angular dependence that depends on the relative polarization and phases of the incident fields. For semiconducting nanotubes we find a similar effect which depends on the square of the semiconducting gap, and we calculate its frequency dependence. We find that the third-order nonlinearity, which controls the direction of the photocurrent is robust for semiconducting tubes and vanishes in the continuum theory for conducting tubes. We calculate corrections to these results arising from higherorder crystal-field effects on the band structure and briefly discuss some applications of the theory.
منابع مشابه
The Molecular Mechanics Model of Carbon Allotropes
Carbon can form numerous allotropes because of its valency. Graphene, carbon nanotubes,capped carbon nanotubes, buckyballs, and nanocones are well-known polymorphs of carbon.Remarkable mechanical properties of these carbon atoms have made them the subject of intenseresearch. Several studies have been conducted on carbon nanotubes or graphene. In the presentstudy, the molecular mechanics method ...
متن کاملHigh temperature acidic oxidation of multiwalled Carbon nanotubes and synthesis of Graphene quantum dots
The acid oxidation of carbon nanotube generally results in opening the close ends of the nanotube and to make surface modifications. Herewith, Multiwall carbon nanotubes (MWCNTs) were oxidized in acids at high temperature experimental conditions which led to the formation of graphene quantum dots (GQDs). High resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectro...
متن کاملHigh temperature acidic oxidation of multiwalled Carbon nanotubes and synthesis of Graphene quantum dots
The acid oxidation of carbon nanotube generally results in opening the close ends of the nanotube and to make surface modifications. Herewith, Multiwall carbon nanotubes (MWCNTs) were oxidized in acids at high temperature experimental conditions which led to the formation of graphene quantum dots (GQDs). High resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectro...
متن کاملInvestigation of the Effects of Graphene Oxide Nanoparticles and Multi-Wall Carbon Nanotubes on Conductivity and Surface Morphology of Polyester-Viscose Fabric
متن کامل
Coherent phonons in carbon nanotubes and graphene
We review recent studies of coherent phonons (CPs) corresponding to the radial breathing mode (RBM) and G-mode in single-wall carbon nanotubes (SWCNTs) and graphene. Because of the bandgap-diameter relationship, RBM-CPs cause bandgap oscillations in SWCNTs, modulating interband transitions at terahertz frequencies. Interband resonances enhance CP signals, allowing for chirality determination. U...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2000