Imaging of Carbon Nanotube Electronic States Polarized by the Field of an Excited Quantum Dot

Nguyễn, Duy Anh; Wallum, Alison; Nguyen, Huy A.; Nguyen, Nhan; Lyding, Joseph W.; Gruebele, Martin

doi:10.1021/acsnano.8b06806

Cited by 3 publications

(2 citation statements)

References 38 publications

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“…As shown previously (7), tip perturbation of the carbon-dot bandgaps at low tunneling current (100 pA) and voltage (∼1 V) is small. However, Stark shift perturbations that occur at high field can be imaged for carbon materials (16).…”

Section: Significancementioning

confidence: 99%

Ultrafast nanometric imaging of energy flow within and between single carbon dots

Nguyen

Srivastava

Pan

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Time- and space-resolved excited states at the individual nanoparticle level provide fundamental insights into heterogeneous energy, electron, and heat flow dynamics. Here, we optically excite carbon dots to image electron–phonon dynamics within single dots and nanoscale thermal transport between two dots. We use a scanning tunneling microscope tip as a detector of the optically excited state, via optical blocking of electron tunneling, to record movies of carrier dynamics in the 0.1–500-ps time range. The excited-state electron density migrates from the bulk to molecular-scale (∼1 nm2) surface defects, followed by heterogeneous relaxation of individual dots to either long-lived fluorescent states or back to the ground state. We also image the coupling of optical phonons in individual carbon dots with conduction electrons in gold as an ultrafast energy transfer mechanism between two nearby dots. Although individual dots are highly heterogeneous, their averaged dynamics is consistent with previous bulk optical spectroscopy and nanoscale heat transfer studies, revealing the different mechanisms that contribute to the bulk average.

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Section: Significancementioning

confidence: 99%

Ultrafast nanometric imaging of energy flow within and between single carbon dots

Nguyen

Srivastava

Pan

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…Thus, a local field enhancement factor (FEF), γ( r ), can be defined as γ( r ) = F ( r )/ F M , where F ( r ) is a particular local field at a point in three-dimensional space. Because of the variable aspect ratio (ratio of longitudinal to lateral dimensions) of CNTs and, consequently, the tunability of their FEFs, they find applications in many areas, ranging from nanoelectronics , to biological sensors. , …”

Section: Introductionmentioning

confidence: 99%

Modeling the Field Emission Enhancement Factor for Capped Carbon Nanotubes Using the Induced Electron Density

Castro

Assis

Rivelino

et al. 2019

J. Chem. Inf. Model.

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In many field electron emission experiments on single-walled carbon nanotubes (SWCNTs), the SWCNT stands on one of two well-separated parallel plane plates, with a macroscopic field FM applied between them. For any given location "L" on the SWCNT surface, a field enhancement factor (FEF) is defined as F L /F M , where F L is a local field defined at "L". The best emission measurements from small-radii capped SWCNTs exhibit characteristic FEFs that are constant (i.e., independent of F M ). This paper discusses how to retrieve this result in quantum-mechanical (as opposed to classical electrostatic) calculations. Density functional theory (DFT) is used to analyze the properties of two short, floating SWCNTS, capped at both ends, namely a (6,6) and a (10,0) structure. Both have effectively the same height (∼ 5.46 nm) and radius (∼ 0.42 nm). It is found that apex values of local induced FEF are similar for the two SWCNTs, are independent of F M , and are similar to FEF-values found from classical conductor models. It is suggested that these induced-FEF values relate to the SWCNT longitudinal system polarizabilities, which are presumed similar. The DFT calculations also generate "real", as opposed to "induced", potential-energy (PE) barriers for the two SWCNTs, for FM-values from 3 V/µm to 2 V/nm. PE profiles along the SWCNT axis and along a parallel "observation line" through one of the topmost atoms are similar. At low macroscopic fields the details of barrier shape differ for the two SWCNT types. Even for F M = 0, there are distinct PE structures present at the emitter apex (different for the two SWCNTs); this suggests the presence of structurespecific chemically induced charge transfers and related patch-field distributions.

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The effectiveness of natural indigo/kaolinite composite powder in the development of latent fingermarks

Leitzke,

Bueno,

Poletti

et al. 2024

Egypt J Forensic Sci

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Background Composites are materials that have multiple phases and have attracted much attention as they are able to improve physical and chemical properties of an isolated material. In this sense, these composites are commonly used as key components for two purposes: coloring and improving the operational properties; besides that, they have alternative synthesis routes that respect the principles of green chemistry. Thus, this reports the development of a new composite using natural products, indigo and kaolinite, for application in papilloscopy as a new nontoxic fingermark developer. Results The composite was obtained via green procedures and was characterized by spectroscopic and chromatographic techniques. Thus, to investigate the potential of the material as a fingermark developer, different techniques were applied such as depletion, aging, comparison with commercial powder, and development of latent fingermarks on different surfaces. Tests revealed that the composite presented good contrast and adhesion with the latent fingermarks, even after 15 days of deposition. Conclusions This study presents a natural indigo/kaolinite composite powder that showed similar or higher efficiency when compared to the commercial fingerprint powder and was able to develop identifiable natural and sebaceous fingermarks. Key points • A composite was formed from eco-friendly materials. • The composite formation follows the concepts of green chemistry and low cost. •The composite was applied as a latent fingermark developer.

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Imaging of Carbon Nanotube Electronic States Polarized by the Field of an Excited Quantum Dot

Cited by 3 publications

References 38 publications

Ultrafast nanometric imaging of energy flow within and between single carbon dots

Ultrafast nanometric imaging of energy flow within and between single carbon dots

Modeling the Field Emission Enhancement Factor for Capped Carbon Nanotubes Using the Induced Electron Density

The effectiveness of natural indigo/kaolinite composite powder in the development of latent fingermarks

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