Charge Transfer Dynamics in Single-Wall Carbon Nanotubes Mat: In Situ Raman Spectroscopy

2003 ◽  
Vol 785 ◽  
Author(s):  
S. Gupta ◽  
M. Hughes ◽  
A.H. Windle ◽  
J. Robertson
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Charge Transfer ◽  
Bond Length ◽  
Mechanical Response ◽  
Radial Breathing Mode ◽  
Single Wall Carbon Nanotubes ◽  
In Situ Raman Spectroscopy ◽  
Single Wall Carbon

ABSTRACTCarbon nanotubes-based actuator has been investigated using in situ Raman spectroscopy in order to understand the actuation mechanism and to determine associated parameters. We built an actuator from a sheet of single-wall carbon nanotubes (SWNT mat) and studied in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide solutions. Since Raman can detect changes in C-C bond length: the radial breathing mode (RBM) at ∼190 cm-1 varies inversely with the nanotube diameter and the G band at ∼1590 cm-1 varies with the axial bond length, the variation of bonding was monitored with potential. In addition, the intensities of both the modes vary with either emptying/depleting or filling of the bonding and antibonding states due to electrochemical charge injection. We discuss the variation of intensity/frequency providing valuable information on the dynamics of charge transfer on the SWNT mat surface. We found the in-plane microscopic strain (∼ -0.25%) and the charge transfer per carbon atom (fc ∼ -0.005) as an upper bound for the electrolytes used. It is demonstrated that though the present analyses does comply with the proposition made earlier, but the quantitative estimates of the associated parameters are significantly lower if compared with those of reported values for carbon nanotubes. Moreover, the extent of variation (i.e. coupled electro-chemo-mechanical response) does depend upon the type of counter-ion used. The cyclic voltammetry (CV) is also described briefly.

Electrochemical Tuning of Single-Wall Carbon Nanotube Mat and Investigations on Actuator Mechanism

2004 ◽  
Vol 855 ◽  
Author(s):  
S. Gupta ◽  
M. Hughes ◽  
J. Robertson
Keyword(s):  
Carbon Nanotubes ◽  
Charge Transfer ◽  
Carbon Nanotube ◽  
Bond Length ◽  
Upper Bound ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Electrochemical Tuning

ABSTRACTElectrochemical tuning of single-wall carbon nanotubes has been investigated using in situ Raman spectroscopy. We built a linear actuator from single-wall carbon nanotube mat and studied in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide solutions. The variation of bonding with electrochemical biasing was monitored using in situ Raman. This is since Raman can detect changes in C-C bond length: the radial breathing mode (RBM) at ∼190 cm−1 varies inversely with the nanotube diameter and the G band at ∼1590 cm−1 varies with the axial bond length. In addition, the intensities of both the modes vary significantly in a nonmonotonic manner pointing at the emptying/depleting or filling of the bonding and anti-bonding states - electrochemical charge injection. We discuss the variation of spectroscopic observables (intensity/frequency) of these modes providing valuable information on the charge transfer dynamics on the single-wall carbon nanotubes mat surface. We found the in-plane compressive strain (∼ -0.25%) and the charge transfer per carbon atom (fc ∼ -0.005) as an upper bound for the electrolytes used i.e. CaCl2. These results can be quantitatively understood in terms of the changes in the energy gaps between the one-dimensional van Hove singularities in the electron density of states arising possibly due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms. Moreover, the extent of variation of the absolute potential of the Fermi level or alternatively modification of band gap is estimated from modeling Raman intensity to be around 0.1 eV as an upper bound for CaCl2.

In Situ Atomic Force Microscopy Tip-Induced Deformations and Raman Spectroscopy Characterization of Single-Wall Carbon Nanotubes

Nano Letters ◽  
2012 ◽  
Vol 12 (8) ◽  
pp. 4110-4116 ◽  
Author(s):  
P. T. Araujo ◽  
N. M. Barbosa Neto ◽  
H. Chacham ◽  
S. S. Carara ◽  
J. S. Soares ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Atomic Force Microscopy ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon ◽  
Force Microscopy ◽  
Atomic Force

Enhanced yield strength in iron nanocomposite with in situ grown single-wall carbon nanotubes

2006 ◽  
Vol 21 (2) ◽  
pp. 522-528 ◽  
Author(s):  
A. Goyal ◽  
D.A. Wiegand ◽  
F.J. Owens ◽  
Z. Iqbal
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Yield Strength ◽  
Vapor Deposition ◽  
Single Wall Carbon Nanotubes ◽  
Iron Matrix ◽  
Single Wall Carbon ◽  
X Ray ◽  
Micro Raman Spectroscopy

The yield strength of iron-carbon nanotube composites fabricated by in situ chemical vapor deposition of 2.2 vol% single-wall carbon nanotubes (SWNTs) inside an iron matrix showed substantial enhancement up to 45%, relative to that of similarly treated pure iron samples without carbon nanotubes of the same piece density. The work hardening coefficient and the Vickers hardness coefficient also significantly increased in these composites relative to the reference samples. X-ray diffraction together with energy dispersive x-ray measurements and micro-Raman spectroscopy indicated no concomitant formation of carbides and very little amorphous carbon during the vapor deposition process. Micro-Raman spectroscopy and scanning and transmission electron microscopy showed spectral signatures and images, respectively, indicating the formation and dispersion of SWNTs within the cavities of the iron matrix. It is suggested that the increased strength of the nanocomposites was due to the mechanical support provided to these cavities by the extremely strong SWNTs.

scholarly journals In situ tracking of defect healing and purification of single-wall carbon nanotubes with laser radiation by time-resolved Raman spectroscopy

RSC Advances ◽  
2015 ◽  
Vol 5 (76) ◽  
pp. 62149-62159 ◽  
Author(s):  
N. Souza ◽  
M. Zeiger ◽  
V. Presser ◽  
F. Mücklich
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Laser Radiation ◽  
Laser Heating ◽  
Single Wall Carbon Nanotubes ◽  
Composite Processing ◽  
Time Resolved ◽  
Single Wall Carbon ◽  
Defect Healing

Fine-tuned localised laser heating of pristine or mechanically dispersed (for composite processing) SWCNTs resulting in precision healing and purification.

Raman spectroscopy of charge transfer interactions between single wall carbon nanotubes and [FeFe] hydrogenase

2008 ◽  
pp. 5454 ◽  
Author(s):  
Jeffrey L. Blackburn ◽  
Drazenka Svedruzic ◽  
Timothy J. McDonald ◽  
Yong-Hyun Kim ◽  
Paul W. King ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Charge Transfer ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon

scholarly journals Electrochemical tuning and mechanical resilience of single-wall carbon nanotubes

2002 ◽  
Vol 74 (9) ◽  
pp. 1719-1730 ◽  
Author(s):  
Shankar Ghosh ◽  
Pallavi V. Teredesai ◽  
A. K. Sood
Keyword(s):  
Carbon Nanotubes ◽  
Radial Breathing Mode ◽  
Single Wall Carbon Nanotubes ◽  
X Ray Diffraction ◽  
Resonance Raman Scattering ◽  
Single Wall Carbon ◽  
Nanotube Bundles ◽  
Energy Gaps ◽  
Electron Density Of States

Single-wall carbon nanotubes (SWNTs) are fascinating systems exhibiting many novel physical properties. In this paper, we give a brief review of the structural, electronic, vibrational, and mechanical properties of carbon nanotubes. In situ resonance Raman scattering of SWNTs investigated under electrochemical biasing demonstrates that the intensity of the radial breathing mode varies significantly in a nonmonotonic manner as a function of the cathodic bias voltage, but does not change appreciably under anodic bias. These results can be quantitatively understood in terms of the changes in the energy gaps between the 1D van Hove singularities in the electron density of states, arising possibly due to the alterations in the overlap integral of π bonds between the π-orbitals of the adjacent carbon atoms. In the second part of this paper, we review our high-pressure X-ray diffraction results, which show that the triangular lattice of the carbon nanotube bundles continues to persist up to ∼10 GPa. The lattice is seen to relax just before the phase transformation, which is observed at ∼10 GPa. Further, our results display the reversibility of the 2D lattice symmetry even after compression up to 13 GPa well beyond the 5 GPa value observed recently. These experimental results explicitly validate the predicted remarkable mechanical resilience of the nanotubes.

Ion transport and electrochemical tuning of Fermi level in single-wall carbon nanotubes: In situ Raman scattering

2007 ◽  
Vol 22 (3) ◽  
pp. 603-614 ◽  
Author(s):  
S. Gupta
Keyword(s):  
Carbon Nanotubes ◽  
Raman Scattering ◽  
Fermi Level ◽  
Bond Length ◽  
Single Wall Carbon Nanotubes ◽  
Raman Intensity ◽  
Overlap Integral ◽  
Single Wall Carbon ◽  
In Situ Raman

The in situ Raman spectroscopy technique was used to investigate the ion transport and to determine the concomitant electrochemical tuning of Fermi level in single-wall carbon nanotubes. The variation of structural bonding in a single-wall carbon nanotube bundle dipped in aqueous alkaline earth halide electrolyte such as CaCl2 with electrochemical biasing was monitored. This is because Raman scattering can detect changes in C–C bond length through radial breathing mode (RBM) at ∼184 cm−1, which varies inversely with the nanotube diameter and the G band at ∼1590 cm−1, varying with the axial bond length. Consistent reversible and substantial variation in Raman intensity of both modes was induced by electrode potential point at the fine and continuous tuning (alternatively, emptying/depleting or filling) of the specific bonding and anti-bonding molecular states. Qualitatively, the results were explained in terms of changes in the energy gap occurring between the one-dimensional van Hove singularities present in the electron density of states, possibly arising due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms. We estimated the extent of variation of the absolute potential of the Fermi level and overlap integral (γ0) between the nearest-neighbor carbon atoms by modeling the electrochemical potential dependence of Raman intensity. Observations also suggested that the work function of the tube becomes larger for the metallic nanotubes in contrast to the simultaneously present semiconducting nanotubes.

Laser-synthesis of single-wall carbon nanotubes with time-resolved in situ diagnostics

2001 ◽  
Author(s):  
David B. Geohegan ◽  
Alex A. Puretzky ◽  
Henrik Schittenhelm ◽  
Xudong Fan ◽  
Phillip F. Britt ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Single Wall Carbon Nanotubes ◽  
Time Resolved ◽  
Laser Synthesis ◽  
Single Wall Carbon ◽  
In Situ Diagnostics
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