The feature of the Breit-Wigner-Fano Raman line in DNA-wrapped single-wall carbon nanotubes

Abstract

Breit-Wigner-Fano (BWF) Raman line in DNA-wrapped single-wall carbon nanotubes (SWNTs) was investigated. For as-produced HiPco SWNT bundles, the asymmetric profile of BWF line is clearly observed with an excitation energy of 2.33eV. The asymmetric feature almost disappears in isolated HiPco SWNTs by DNA wrapping in aqueous solution. Such a significant change provides evidence that the asymmetric feature of BWF line is attributed to the bundling effect of SWNTs. In addition, the asymmetric feature of BWF line strongly appears even when the DNA-wrapped SWNTs are exposed to air. This means that the rebundling in the DNA-wrapped SWNTs can occur due to drying.

Raman spectroscopy of DNA-wrapped single-walled carbon nanotube films at 295 and 5K

“…Upon the preparation of nanotube films from water suspension with DNA, a composite is formed in which individual nanotubes or small bundles are separated with the polymer [7,8]. This conclusion is confirmed with the observation of the luminescence of SWNT:DNA film, which suggests the presence of individual tubes as in nanotube bundles a luminescence is quenched because of the semiconducting SWNT contact with metallic ones [7].…”

Low-energy electron irradiation of preheated and gas-exposed single-wall carbon nanotubes

“…The BWF peak in bundles has been reported to increase as a result of tube-tube interactions that are thought to produce a plasmon band that increases the plasmon-phonon coupling [28]. For example, when bundles are reduced in size [28], or the nanotubes within a bundle are isolated by oxidation [29] or wrapped with DNA molecules [26,27], the BWF peak decreases. The BWF peak increases again when the oxide or DNA molecules are removed.…”

“…The 1517 cm − 1 curve can be attributed to a G −S peak from the small diameter E22 S semiconducting nanotubes of E2g symmetry overlapped with a G −M peak from mid diameter nanotubes with E11 M transitions and A1g symmetry. The 1542 cm − 1 curve can be attributed to the G −M peak from upper mid diameter metallic nanotubes with E11 M transitions and A1g symmetry in which inter-tube electron-phonon coupling does not appear to occur [26,27]. The 1572 cm − 1 curve can be attributed to the G −S peak of the large diameter semiconducting nanotubes with E33 S transitions and E1g symmetry, and the 1585 cm −1 curve can be attributed to the G + peak for both metallic and semiconducting nanotubes.…”

Spin filtering with poly-T wrapped single wall carbon nanotubes

“…It is important to note that the Raman G band never exhibited the Breit-Wigner-Fano (BWF) lineshape, which is the signature of metallic nanotubes 17,18 . Such features are expected to appear when metallic tubes with nominal diameter of ~1nm are excited with 532nm laser.…”

“…A droplet containing wrapped carbon nanotubes (as discussed above) was subsequently cast on the gap. After 15 minutes the solution was washed out, followed by nitrogen drying and vacuum annealing several groups [17][18][19][20] . This shift is slightly less than what we had found in our previous study on d(GT) 15 11 , which could be attributed to the difference in chemical compositions of the DNA strands.…”