Terahertz transmission ellipsometry of vertically aligned multi-walled carbon nanotubes

Paul, M. J.; Kuhta, Nicholas A.; Jameson, A.; Maizy, Louis; Sharf, Tal; Rupesinghe, N. L.; Teo, Kenneth B. K.; Inampudi, Sandeep; Podolskiy, Viktor A.; Minot, Ethan D.; Lee, Yun-Shik

doi:10.1063/1.4752158

Cited by 13 publications

(9 citation statements)

References 31 publications

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“…For example, transmission electron microscopy (TEM) has been utilized to identify the well-ordered crystalline heterostructures in the interfacial area between SWCNTs and carbide nanorods . Scanning tunneling microscopy (STM) has been employed to examine the electronic density of SWCNTs at an atomic resolution. − Not long ago, the time-resolved terahertz (THz) transmission ellipsometry was used to demonstrate the unexpected weak anisotropy comparing to the strong transverse electrical conduction for aligned MWCNTs, indicating that the electron transport between the adjacent MWCNTs shells was easily induced by the THz field . Also, the thickness of an interfacial layer between MWCNTs and SWCNTs with reflux and ultrasonic treatments has quantitatively been characterized via a peak force nanomechanical mapping (PF-QNM) method using atomic force microscopy (AFM). , In addition, thermodynamic and HPLC techniques were also applied into quantitative analysis of specific molecular interactions on SWCNT surfaces .…”

Section: Introductionmentioning

confidence: 99%

“…23−25 MWCNTs, indicating that the electron transport between the adjacent MWCNTs shells was easily induced by the THz field. 26 Also, the thickness of an interfacial layer between MWCNTs and SWCNTs with reflux and ultrasonic treatments has quantitatively been characterized via a peak force nanomechanical mapping (PF-QNM) method using atomic force microscopy (AFM). 27,28 In addition, thermodynamic and HPLC techniques were also applied into quantitative analysis of specific molecular interactions on SWCNT surfaces.…”

Section: ■ Introductionmentioning

confidence: 99%

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Polar Solvents Induce Sum Frequency Generation Activity for Multiwalled Carbon Nanotubes

Yin

et al. 2021

Langmuir

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Regarding methods of process and use of carbon nanotubes (CNTs), solvents are generally employed to disperse or dissolve CNTs as a pretreatment or intermediate process step. This naturally imposes an essential issue on how CNTs and solvents interact with each other, which seems trivial, comparatively inconsequential, and might often be overlooked from the perspective of engineering scenarios. However, as a matter of fact, it is indeed a fascinating and significant topic. In this article, to investigate the interfacial properties of multiwalled CNTs (MWCNTs) exposed to widely utilized solvents, we applied sum frequency generation vibrational spectroscopy (SFG-VS) to probe solvent-wetted MWCNTs and proved that polar solvents can substantially alter the interfacial optical property of MWCNTs. First, the interfacial optical phonon vibrational modes were detected when MWCNTs were wetted by polar solvents, i.e., water and dimethylformamide (DMF), while such modes were inactive when the solvents were nonpolar, i.e., decalin and air. Second, the interfacial optical phonon vibration frequency displayed distinct dependence on surface defects of MWCNTs. Combining theoretical analysis with experimental verification, a valid conjecture with respect to surface phonon vibration activity for MWCNTs was proposed. This phenomenon of polar solvent-induced SFG activity may have the potential to find applications in optical detection and environmental sensing in the near future.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Polar Solvents Induce Sum Frequency Generation Activity for Multiwalled Carbon Nanotubes

Yin

et al. 2021

Langmuir

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“…While the THz-mid-infrared conductivity response of (aligned) single-wall (SW) CNT films has been studied in detail [7][8][9][10][11][12], such studies for the case of VACNT are relatively few [13][14][15], and to our knowledge, restricted to low frequencies (i.e. in the conventional THz range below ∼3 THz), which motivated the experiments extending into the IR spectral range presented below.…”

Section: Introductionmentioning

confidence: 99%

Dielectric properties of vertically aligned multi-walled carbon nanotubes in the terahertz and mid-infrared range

Thomson¹,

Zouaghi²,

Meng³

et al. 2017

J. Phys. D: Appl. Phys.

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We investigate the broadband dielectric properties of vertically aligned, multi-wall carbon nanotubes (VACNT), over both the terahertz (THz) and mid-infrared spectral ranges. The nominally undoped, metallic VACNT samples are probed at normal incidence, i.e. the response is predominantly due to polarisation perpendicular to the CNT axis. A detailed comparison of various conductivity models and previously reported results is presented for the non-Drude behaviour we observe in the conventional THz range (up to 2.5 THz). Extension to the mid-infrared range reveals an absorption peak at ∼24 THz, reminiscent of that observed in single-wall CNT, only there it arises for polarisation parallel to the CNT axis. To account for the observed resonance here, we apply a Bergman-type effective-medium theory, based on first-principles' electromagnetic simulations for the perpendicular polarisation including both the intra-and inter-tube response, which can reproduce the observed spectrum if one assumes a much higher plasma frequency and scattering rate than that reflected in the low-frequency spectra, and proposes an explanation for the non-Drude behaviour at low-frequencies.

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“…Electron dynamics in carbon nanotubes (CNTs) typically fall in the terahertz (THz) frequency region. [1][2][3][4] The high responsivity of CNTs to THz electromagnetic waves creates great potential for a wide range of applications, including ultrafast nanoelectronics, [5][6][7] THz sources 8,9 and detectors, [10][11][12] and THz optical elements. 13,14 CNT based THz polarizers, in particular, exploit the highly anisotropic THz response of quasi-one-dimensional CNTs.…”

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confidence: 99%

Anisotropic high-field terahertz response of free-standing carbon nanotubes

Lee

Mousavian

Paul

et al. 2016

Applied Physics Letters

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We demonstrate that unidirectionally aligned, free-standing multi-walled carbon nanotubes (CNTs) exhibit highly anisotropic linear and nonlinear terahertz (THz) responses. For the polarization parallel to the CNT axis, strong THz pulses induce nonlinear absorption in the quasi-one-dimensional conducting media, while no nonlinear effect is observed in the perpendicular polarization configuration. Time-resolved measurements of transmitted THz pulses and a theoretical analysis of the data reveal that intense THz fields enhance permittivity in carbon nanotubes by generating charge carriers.

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Terahertz transmission ellipsometry of vertically aligned multi-walled carbon nanotubes

Cited by 13 publications

References 31 publications

Polar Solvents Induce Sum Frequency Generation Activity for Multiwalled Carbon Nanotubes

Polar Solvents Induce Sum Frequency Generation Activity for Multiwalled Carbon Nanotubes

Dielectric properties of vertically aligned multi-walled carbon nanotubes in the terahertz and mid-infrared range

Anisotropic high-field terahertz response of free-standing carbon nanotubes

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