Terahertz characterization of multi-walled carbon nanotube films

Wu, Ziran; Wang, Lu; Peng, Yitian; Young, Abram; Seraphin, Suṗapan; Xin, Hao

doi:10.1063/1.2919784

Cited by 27 publications

(18 citation statements)

References 15 publications

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“…For example, in the case of normal incidence, the zeroth-order transmission coefficient , and the first-order coefficient due to one time of Fabry-Perot reflection, can be expressed as (see [14]) where is the frequency, is the sample thickness, is the speed of light, and is the refractive index of the sample. Because the foam sample has a refractive index close to 1 (free-space) the first-order term and all higher order terms are close to zero, and thus indistinguishable as separated pulses in the output time-domain waveform.…”

Section: Dielectric Materials Property Determinationmentioning

confidence: 99%

“…In the data extraction, it is found that after the second term is included, the solution converges. The rest of the extraction is simply fitting the term with the measured complex transmission coefficient numerically, and determine the value of complex at each frequency ( [14]). Once the refractive index is extracted, the sample permittivity is obtained as .…”

Section: Dielectric Materials Property Determinationmentioning

confidence: 99%

“…Since the sample's permeability a transmission characterization is enough to measure its dielectric response ( [12]- [14]). In THz-TDS transmission measurement the sample is placed in the THz pulse beam path between the transmitter and the receiver.…”

Section: Dielectric Materials Property Determinationmentioning

confidence: 99%

See 2 more Smart Citations

Mechanical Damage Detection in Polymer Tiles by THz Radiation

Rahani

Kundu

et al. 2011

IEEE Sensors J.

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Today the ultrasonic inspection technique is probably the most popular method for nondestructive evaluation and structural health monitoring. However, ultrasonic waves are not very effective in detecting internal defects in some materials such as ceramic foam tiles used in the thermal protection system (TPS) of the space shuttle, thick polymer composites, and polymer tiles used in various applications. Ultrasonic energy is attenuated very fast in these materials. On the other hand the electromagnetic radiation in THz (1000 GHz) frequency range can penetrate deep inside these materials. Its wavelength is small enough to detect internal defects. To understand the limits of structural damage detection capability of THz electromagnetic radiation or T-ray, mechanical damage in polymer tiles is introduced by drilling holes. Then T-ray is passed through the damaged and defect-free tiles. The received signal strength is found to be affected differently by the internal defect as the frequency changes. Experimental observations are justified from the model predictions. The model takes into account the interaction between the T-ray of finite width and the tile containing the internal defect.Index Terms-dielectric properties, electromagnetic scattering by absorbing media, electromagnetic scattering by dispersive media, nondestructive testing, THz time-domain spectroscopy.

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Section: Dielectric Materials Property Determinationmentioning

confidence: 99%

Section: Dielectric Materials Property Determinationmentioning

confidence: 99%

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Mechanical Damage Detection in Polymer Tiles by THz Radiation

Rahani

Kundu

et al. 2011

IEEE Sensors J.

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“…Since no magnetic behavior is expected from the material, its permeability μ = 1. The complex permittivity was determined by performing a single transmission experiment using THz-TDS [17][18][19][20]. The dielectric constant ε" and the loss tangent tan δ = ε""/ε" (a convenient parameter representing the loss in a dielectric material) were extracted from the measured magnitude and phase of the transmission coefficient of the block polymer material.…”

Section: Dielectric Materials Property Determinationmentioning

confidence: 99%

Heat Induced Damage Detection by Terahertz (THz) Radiation

Rahani

Kundu

et al. 2011

J Infrared Milli Terahz Waves

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Terahertz (THz) and sub-terahertz imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. THz radiation is being used for inspecting ceramic foam tiles used in TPS (Thermal Protection System), thick polymer composites and polymer tiles that are not good conductors of ultrasonic waves. Capability of THz electromagnetic waves in detecting heat induced damage in porous materials is investigated in this paper. Porous pumice stone blocks are subjected to long time heat exposures to produce heat induced damage in the block. The dielectric properties extracted from THz TDS (Time Domain Spectroscopy) measurements are compared for different levels of heat exposure. Experimental results show noticeable and consistent change in dielectric properties with increasing levels of heat exposure, well before its melting point.

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“…The MWCNT papers have reported studies in the 8-50 GHz range [1,5]. MWCNTs deposited on a silicon wafer have been measured in the X-band (8-12 GHz) [6].…”

mentioning

confidence: 99%

Sub‐THz characterisation of multi‐walled carbon nanotube thin films using vector network analyser

et al. 2014

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A vector network analyser is used to study the electrical properties of multi-walled carbon nanotube (MWCNT) thin films deposited on a fused quartz substrate in the sub-terahertz (THz) frequency ranges of 220-325 GHz (WR3.4) and 325-500 GHz (WR2.2). The experiment is performed in free space. The complex permittivity of the MWCNT thin films is extracted using the Nicholson-Ross-Weir method. The refractive index and conductivity are then determined from the extracted permittivity. The method is validated by comparison with values obtained using THz time-domain spectroscopy

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Terahertz characterization of multi-walled carbon nanotube films

Cited by 27 publications

References 15 publications

Mechanical Damage Detection in Polymer Tiles by THz Radiation

Mechanical Damage Detection in Polymer Tiles by THz Radiation

Heat Induced Damage Detection by Terahertz (THz) Radiation

Sub‐THz characterisation of multi‐walled carbon nanotube thin films using vector network analyser

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