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We study carrier interaction induced many-body effects on the excitonic optical properties of highly photoexcited one-dimensional semiconductor quantum wire systems by solving the dynamically screened Bethe-Salpeter equation using realistic…

Strongly Correlated Electrons · Physics 2009-11-07 D. W. Wang , S. Das Sarma

Employing the interband exciton scattering model, we have performed a numerical study of the direct photogeneration and population relaxation processes contributing to carrier multiplication (CM) in nanocrystalline and bulk PbSe. We argue…

Mesoscale and Nanoscale Physics · Physics 2016-11-25 Kirill A. Velizhanin , Andrei Piryatinski

We present the numerical tool DECaNT (Diffusion of Excitons in Carbon NanoTubes) that simulates exciton transport in thin films of carbon nanotubes. Through a mesh of nanotubes generated using the Bullet Physics C++ library, excitons move…

Mesoscale and Nanoscale Physics · Physics 2021-04-01 S. W. Belling , Y. C. Li , A. H. Davoody , A. J. Gabourie , I. Knezevic

Single-walled carbon nanotubes are strongly correlated systems with large Coulomb repulsion between two electrons occupying the same $p_z$ orbital. Within a molecular Hamiltonian appropriate for correlated $\pi$-electron systems, we show…

Materials Science · Physics 2009-02-15 Zhendong Wang , Demetra Psiachos , Roberto F. Badilla , Sumit Mazumdar

We use the macroscopic quantum electrodynamics approach suitable for absorbing and dispersing media to study the properties and role of collective surface excitations --- excitons and plasmons --- in single-wall and double-wall carbon…

Mesoscale and Nanoscale Physics · Physics 2017-08-14 I. V. Bondarev , L. M. Woods , A. Popescu

Covalent functionalization of semiconducting single-wall carbon nanotubes (CNT) introduces new photoluminescent emitting states. Theses states are spatially localized at around functionalization sites and strongly red-shifted relative to…

Mesoscale and Nanoscale Physics · Physics 2020-01-08 Kirill A. Velizhanin

Pump-dependent photoluminescence imaging and 2nd order photon correlation studies have been performed on individual single-walled carbon nanotubes (SWCNTs) at room temperature that enable the extraction of both the exciton diffusion…

Mesoscale and Nanoscale Physics · Physics 2015-07-10 Xuedan Ma , Oleskiy Roslyak , Juan G. Duque , Xiaoying Pang , Stephen K. Doorn , Andrei Piryatinski , David H. Dunlap , Han Htoon

We study how shape affects multiexciton generation (MEG) rates in a semiconducting nanocrystal by considering CdSe nanorods with varying diameters and aspect ratios. The calculations employ an atomistic semiempirical pseudopotential model…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 Roi Baer , Eran Rabani

We report a femtosecond mid-infrared study of the broadband low-energy response of individually separated (6,5) and (7,5) single-walled carbon nanotubes. Strong photoinduced absorption is observed around 200 meV, whose transition energy,…

Mesoscale and Nanoscale Physics · Physics 2010-07-16 Jigang Wang , Matt W. Graham , Yingzhong Ma , Graham R. Fleming , Robert A. Kaindl

Theory predicts peculiar features for excited-state dynamics in one dimension (1D) that are difficult to be observed experimentally. Single-walled carbon nanotubes (SWNTs) are an excellent approximation to 1D quantum confinement, due to…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Giancarlo Soavi , Francesco Scotognella , Daniele Viola , Timo Hefner , Tobias Hertel , Giulio Cerullo , Guglielmo Lanzani

Carbon nanotubes are a fraction of the size of transistors used in today's best microchips, as it could reduce power demands and heating in next electronics revolution. Present study investigates the electronic and magnetic structure of…

Materials Science · Physics 2012-01-09 Sanjeev Gautama , P. Thakur , S. Augustine , J. K. Kang , J. -Y. Kim , N. B. Brookes , K. Asokan , Keun Hwa Chae

The effect of carrier multiplication (CM) in semiconductor nanocrystals is systematically treated by employing an exciton scattering approach. Using projection operators, we reduce the Coulomb coupled multi-exciton dynamics to scattering…

Mesoscale and Nanoscale Physics · Physics 2010-08-31 Andrei Piryatinski , Kirill A. Velizhanin

Excitons, namely neutral excitations in a system of electrons arising from the electron-hole interaction, are often essential to explain optical measurements in materials. They are governed by the Bethe-Salpeter equation, which can be cast…

Strongly Correlated Electrons · Physics 2024-10-29 M. A. García-Blázquez , J. J. Palacios

A detailed understanding of energy transduction is crucial for achieving precise control of energy flow in complex, integrated systems. In this context, carbon nanotubes (CNTs) are intriguing model systems due to their rich,…

Mesoscale and Nanoscale Physics · Physics 2011-02-16 Eyal Shafran , Benjamin D. Mangum , Jordan M. Gerton

We present many-body \textit{ab initio} calculations of the electronic and optical properties of semiconducting zigzag carbon nanotubes under uniaxial strain. The GW approach is utilized to obtain the quasiparticle bandgaps and is combined…

Materials Science · Physics 2015-06-16 Catalin D. Spataru , François Léonard

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

Excitons are electron-hole pairs appearing below the band gap in insulators and semiconductors. They are vital to photovoltaics, but are hard to obtain with time-dependent density-functional theory (TDDFT), since most standard…

Materials Science · Physics 2013-05-22 Zeng-hui Yang , Carsten A. Ullrich

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

The electrons and excitons multiple exciton generation dynamics in two silicon clusters, or more specifically the inelastic scattering rates of electronic and excitonic states in the two silicon clusters, Si26 and Si46, are calculated using…

Mesoscale and Nanoscale Physics · Physics 2020-07-14 Taofang Zeng , Yi He

We present detailed analysis of the non-Poissonian population of excitons produced by MEG effect in quantum dots on the base of statistic theory of MEG and synergetic approach for chemical reactions. From the analysis we can conclude that a…

Quantum Physics · Physics 2015-05-28 N. N. Turaeva , B. L. Oksengendler , I. Uralov