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We report that dark excitons can have a large contribution to the emission intensity in carbon nanotubes due to an efficient exciton conversion from a dark state to a bright state. Time-resolved photoluminescence measurements are used to…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 A. Ishii , H. Machiya , Y. K. Kato

We introduce a new simplified method for computing the electron field emission current in short carbon nanotubes using ab-initio computation in periodic simulation cells. We computed the evolution of the wave functions using Time-Dependent…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Sherif Tawfik , Salah El Sheikh , Noha Salem

We report a method for probing electromechanical properties of multiwalled carbon nanotubes(CNTs). This method is based on AFM measurements on a doubly clamped suspended CNT electrostatically deflected by a gate electrode. We measure the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 R. Lefevre , M. F. Goffman , V. Derycke , C. Miko , L. Forro , J. P. Bourgoin , P. Hesto

Amorphous carbon nanotubes (a-CNT) with up to four walls and sizes ranging from 200 to 3200 atoms have been simulated, starting from initial random configurations and using the Gaussian Approximation Potential [Phys. Rev. B 95, 094203…

Materials Science · Physics 2023-03-22 C. Ugwumadu , R. Thapa , Y. Al-Majali , J. Trembly , D. A. Drabold

In this work we present a computational study of the small strain mechanics of freestanding ultrathin CNT films under in-plane loading. The numerical modeling of the mechanics of representatively large specimens with realistic micro- and…

Mesoscale and Nanoscale Physics · Physics 2019-10-22 Igor Ostanin , Traian Dumitrică , Sebastian Eibl , Ulrich Rüde

Carbon nanotubes (CNTs) are currently considered a successor to silicon in future nanoelectronic devices. To realize this, controlled growth of defect-free nanotubes is required. Until now, the understanding of atomic-scale CNT growth…

Materials Science · Physics 2023-03-16 Daniel Hedman , Ben McLean , Christophe Bichara , Shigeo Maruyama , J. Andreas Larsson , Feng Ding

Through an investigation of photoemission properties of highly-photoexcited single-walled carbon nanotubes, we demonstrate that there is an upper limit on the achievable excitonic density. As the intensity of optical excitation increases,…

Materials Science · Physics 2009-07-31 Yoichi Murakami , Junichiro Kono

To provide physical insight into the recently observed photoluminescence saturation behaviors in single-walled carbon nanotubes implying the existence of an upper limit of exciton densities, we have performed a time-dependent theoretical…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Ajit Srivastava , Junichiro Kono

The intrinsic near-infrared photoluminescence observed in long single walled carbon nanotubes is systematically quenched in ultrashort single-walled carbon nanotubes (usCNTs, below 100 nm length) due to their short dimension as compared to…

Double-walled carbon nanotubes (DWCNTs) with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and more than half of the…

Materials Science · Physics 2011-05-17 Lei Shi , Leimei Sheng , Liming Yu , Kang An , Yoshinori Ando , Xinluo Zhao

Using molecular dynamics simulations, we predict an effect of chirality on the conduction of benzene molecules along the surface of carbon nanotubes (CNTs) subjected to a thermal gradient. The group drift velocity of the molecules is found…

Mesoscale and Nanoscale Physics · Physics 2020-09-17 Zhao Wang

Controlled growth, patterning and placement of carbon nanotube (CNT) thin films for electronic applications are demonstrated. The density of CNT films is controlled by optimizing the feed gas composition as well as the concentration of…

Materials Science · Physics 2015-05-18 V. K. Sangwan , V. W. Ballarotto , D. R. Hines , M. S. Fuhrer , E. D. Williams

Light emission from carbon nanotubes is expected to be dominated by excitonic recombination. Here we calculate the properties of excitons in nanotubes embedded in a dielectric, for a wide range of tube radii and dielectric environments. We…

Materials Science · Physics 2009-11-10 Vasili Perebeinos , J. Tersoff , Phaedon Avouris

Dielectric properties of carbon nanotubes (CNT) are calculated with taking into account the deviation of carbon valence electrons from to be placed exactly on the CNT surface. The results show difference to the usually applied 2D electron…

Mesoscale and Nanoscale Physics · Physics 2012-04-04 V. A. Aleksandrov , A. V. Stepanov , G. M. Filippov

Optical properties of single-wall carbon nanotubes (SWCNTs) for light polarized parallel to the nanotube axis have been extensively studied, whereas their response to light polarized perpendicular to the nanotube axis has not been well…

Mesoscale and Nanoscale Physics · Physics 2019-01-23 Fumiya Katsutani , Weilu Gao , Xinwei Li , Yota Ichinose , Yohei Yomogida , Kazuhiro Yanagi , Junichiro Kono

At cryogenic temperature and at the single emitter level, the optical properties of single-wall carbon nanotubes depart drastically from that of a one-dimensional (1D) object. In fact, the (usually unintentional) localization of excitons in…

Microtribological properties of vertically-aligned carbon-nanotube (VACNT) films have been studied. Adhesion forces were obtained by measuring force-displacement curves. Friction experiments were conducted in reciprocating sliding…

Materials Science · Physics 2008-12-18 H. Kinoshita , Ippei Kume , Masahito Tagawa , N. Ohmae , Viviane Turq , J. M. Martin

The properties of excitons in semiconducting single-walled carbon nanotubes (SWCNTs), isolated in vacuum or a medium, and their contributions to the optical spectra of nanotubes are studied within the elementary potential model, in which an…

Materials Science · Physics 2010-12-15 Oleksii A. Smyrnov

Carbon nanotubes (CNTs) are a promising material for high-performance electronics beyond silicon. But unlike silicon, the nature of the transport band gap in CNTs is not fully understood. The transport gap in CNTs is predicted to be…

We present a theoretical study of the directionality effects in spontaneous emission and resonance fluorescence of a quantum two-level dipole emitter near an ultrathin closely packed periodically aligned single-wall carbon nanotube film.…

Mesoscale and Nanoscale Physics · Physics 2024-10-15 Michael D. Pugh , SK Firoz Islam , Igor V. Bondarev