Optical identification of a DNA-wrapped carbon nanotube: signs of helically broken symmetry.
نویسندگان
چکیده
High intrinsic mobility and small, biologically compatible size make single-walled carbon nanotubes (SWNTs) in demand for the next generation of electronic devices. Further, the wide range of available bandgaps due to changes in diameter and symmetry give SWNTs greater versatility than traditional semiconductors. Single-stranded DNA has been employed to make these desirable properties accessible for large-scale fabrication of devices. Because single-stranded DNA can helically wrap an SWNT, forming a stable hybrid structure, DNA/polymer wrapping has been used to disperse bundles of intrinsically hydrophobic SWNTs into individual tubes in aqueous solution. The ability to isolate individual tubes, make them soluble, and separate them according to symmetry would enable fabrication of SWNT optoelectronic devices that benefit from the unique electronic properties of specific nanotube structures. Envisioning optoelectronic applications of nanotubes, we investigate whether the optical properties of DNA-wrapped SWNT materials are different to those of pristine SWNTs. Our previous work found that bandstructures of DNA–SWNTs are indeed affected by the charged wrap. That is, the direct optical bandgap, E11, decreases, but changes are fairly small. [8] This is consistent with the available experimental data in standard experimental geometry in which incident light is polarized along the SWNT axis. Here we consider optical absorption of light with perpendicular (or circular) polarization with respect to the tube axis, which has been measured experimentally for SWNTs dispersed using a surfactant. In this geometry we find qualitative changes in the absorption spectra
منابع مشابه
Supporting Information for ”Optical Identification of a DNA-Wrapped Carbon Nanotube: Signs of Helically Broken Symmetry” by S. E. Snyder, S. V. Rotkin
The cause of helical symmetry breaking of the nanotube is a combination of the Coulomb potentials of the partial charges of the atoms of single stranded DNA and the electrons on the SWNT itself, moving in the field of the DNA. Table 1 shows partial atomic charges for a specific DNA base. Since many atomic charges are small and partially cancel the effects of nearby charges, we often approximate...
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عنوان ژورنال:
- Small
دوره 4 9 شماره
صفحات -
تاریخ انتشار 2008