Combined experimental andab initiostudy of the electronic structure of narrow-diameter single-wall carbon nanotubes with predominant (6,4),(6,5) chirality

Abstract

Narrow diameter tubes and especially ͑6,5͒ tubes with a diameter of 0.75 nm are currently one of the most studied carbon nanotubes because their unique optical and especially luminescence response makes them exceptionally suited for biomedical applications. Here we report on a detailed analysis of the electronic structure of nanotubes with ͑6,5͒ and ͑6,4͒ chiralities using a combined experimental and theoretical approach. From high-energy spectroscopy involving x-ray absorption and photoemission spectroscopy the detailed valence-and conduction-band response of these narrow diameter tubes is studied. The observed electronic structure is in sound agreement with state of the art ab initio calculations using density-functional theory.

Templating rare-earth hybridization via ultrahigh vacuum annealing of ErCl3nanowires inside carbon nanotubes

“…2 together with a line-shape analysis that includes the corresponding vHs (identified by the labels on top of the curves). This is in very good agreement with the results published previously for SWCNTs, [19][20][21][22] which clearly show the localized response from the vHs. In addition the foot at low energy can be assigned to the vHs of the semiconducting tubes, which is screened by the encapsulated material, as extensively discussed in Ref.…”

“…The fine structure in the π response can be unambiguously assigned to the matrix element weighted density of states (DOS), which is strongly influenced by core hole effects along the tube axes and only weakly modified for the response from the van Hove singularities (vHs) polarized perpendicular to the tube axis. [19][20][21][22] The results of the C1s XAS response for the pristine and heat treated samples are depicted in Fig. 2 together with a line-shape analysis that includes the corresponding vHs (identified by the labels on top of the curves).…”

Computing C1<I>s</I> X-ray Absorption for Single-Walled Carbon Nanotubes with Distinct Electronic Type

“…In Fig. 3 we have removed the remaining discrepancy by shifting the theoretical C1s onset energies up by 0.7 eV and 1.5 eV for the (10,10) and (17,0) SWNTs, respectively.…”

“…Both have been analyzed in several studies for graphitic systems (see the overall spectrum in the inset of figure 1). However, in the case of SWCNTs, which are structures with unique onedimensional electronic properties, additional features in the core level XAS spectrum have only recently been revealed experimentally [3,[8][9][10]. In this article we outline the C1s response in XAS, which is again related to the density of states of the conduction band in SWCNTs and its fine structure revealed by experiments performed specifically on metallicitysorted SWCNT material [11].…”

Photoemission of low-dimensional carbon systems

“…Studies over the last few years have set the basis for understanding doping-dependent modifi cations regarding the bonding environment and charge transfer at the carbon sites of metallic and semiconducting SWCNTs in unprecedented detail. 11,12,30 …”