We have investigated the photoluminescence (PL) of in individual single-walled carbon nanotubes (SWNTs) placed in field-effect transistor structures to study carrier transport in the SWNT. The relation between the recombination lifetime and carrier transit time has been evaluated from the drain-field dependence of PL intensity. Time-resolved photoluminescence of SWNTs dispersed in surfactant so...

In spite of the outstanding properties of single-walled carbon nanotubes (SWNTs), the coexistence of metallic and semiconducting SWNTs as a result of synthesis has hindered their electronic and photonic applications. We demonstrate a pump-probe microscopy method for fast, contact-free mapping of metallicity in individual SWNTs. We employ the phase of transient absorption as a contrast to discri...

Three different carbon-based counter electrodes are investigated in light of catalytic activities such as electrochemical frequencies and interface impedances. We fabricated carbon-based counter electrodes of dye-sensitized solar cells [DSSCs] using graphene, single-walled carbon nanotubes [SWNTs], and graphene-SWNT composites by electrophoretic deposition method. We observed the optical and el...

We describe a general method to integrate DNA strands between single-walled carbon nanotube electrodes and to measure their electrical properties. We modified DNA sequences with amines on either the 5' terminus or both the 3' and 5' termini and coupled these to the single-walled carbon nanotube electrodes through amide linkages, enabling the electrical properties of complementary and mismatched...

Resonance Raman studies on single wall carbon nanotubes (SWNTs) show that resonance with cross polarized light, i.e., with the E(mu,mu+/-1) van Hove singularities in the joint density of states needs to be taken into account when analyzing the Raman and optical absorption spectra from isolated SWNTs. This study is performed by analyzing the polarization, laser energy, and diameter dependence of...

Current methods for producing single-walled carbon nanotubes (SWNTs) lead to heterogeneous samples containing mixtures of metallic and semiconducting species with a variety of lengths and defects. Optical detection at the single nanotube level should thus offer the possibility to examine these heterogeneities provided that both SWNT species are equally well detected. Here, we used photothermal ...

Understanding of the fundamental photoresponse of carbon nanotubes has broad implications for various photonic and optoelectronic devices. Here, Z-scan and pump-probe spectroscopy performed across 600-2400 nm were combined to give a broadband 'degenerate' mapping of the nonlinear absorption properties of single-wall carbon nanotubes (SWNTs). In contrast to the views obtained from non-degenerate...

We studied the femtosecond dynamics of photoexcitations in films containing semiconducting and metallic single-walled carbon nanotubes (SWNTs), using various pump-probe wavelengths and intensities. We found that confined excitons and charge carriers with subpicosecond dynamics dominate the ultrafast response in semiconducting and metallic SWNTs, respectively. Surprisingly, we also found from th...

Anisotropic optical absorption properties of single-walled carbon nanotubes (SWNTs) are determined from a vertically aligned SWNT film for 0.5-6 eV. Absorption peaks at 4.5 and 5.25 eV are found to exhibit remarkable polarization dependence and have relevance to optical properties of graphite. A method for determining a nematic order parameter for an aligned SWNT film based on the collinear abs...

We measured the UV optical absorption of single-stranded DNA bound to single-walled carbon nanotubes (DNA/SWNT). The nucleotide absorbance from DNA/SWNT provides the first experimental confirmation that DNA binds to nanotubes through pi-stacking. Because the hypochromic absorbance typical of pi-stacked structures are expected to occur primarily for DNA dipole transitions that lie along the axis...