Terahertz Spectroscopy
Terahertz Spectroscopy - Related Videos
07:28
Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor
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Cited by 3 •
2012
The procedure for implementing a refractive index sensor for terahertz frequencies based on a grooved parallel-plate waveguide geometry is described here. The method yields a measurement of the refractive index of a small volume of liquid through monitoring of the shift in the resonant frequency of the waveguide...
10:54
Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
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Cited by 9 •
2013
We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.
09:21
Mössbauer Spectroscopy
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2023
Source: Joshua Wofford, Tamara M. Powers, Department of Chemistry, Texas A&M University Mössbauer spectroscopy is a bulk characterization technique that examines the nuclear excitation of an atom by gamma rays in the solid state. The resulting Mössbauer spectrum provides information about the oxidation state, spin state, and electronic environment around the target atom, which, in combination, gives evidence about the electronic structure and ligand arrangement (geometry) of the molecule.
10:28
Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials
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Cited by 1 •
2017
A protocol for the design and fabrication of a novel nanopillar-based split ring resonator (SRR) is presented.
08:11
Infrared Spectroscopy
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2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the use of infrared (IR) spectroscopy (also known as vibrational spectroscopy) to elucidate the identity of an unknown compound by identifying the functional group(s) present. IR spectra will be obtained on an IR spectrometer using the attenuated total reflection (ATR) sampling technique with a neat sample of the unknown.
FAQs
A time-domain system records the changing terahertz electric-field transient after ultrashort laser pulses generate and detect it. Converting this signal into a frequency spectrum separates the response by frequency, making absorption, reflection, and refractive-index features easier to identify. Engineers can then relate those features to material composition, structure, or dynamic behavior.
These spectral features describe different aspects of how a material interacts with terahertz radiation. Absorption can indicate frequency-dependent energy uptake, reflection shows how strongly an interface returns radiation, and refractive-index behavior describes propagation through the material. Together, they provide complementary evidence for evaluating composition, structure, and performance in engineered materials.
They represent distinct material dynamics that can influence the measured terahertz response. Molecular rotations relate to internal motion, lattice vibrations reflect behavior within structured solids, and charge transport describes how carriers respond in materials such as semiconductors. Observing their contributions helps connect spectral features with physical mechanisms rather than treating the spectrum as an unexplained pattern.
Time-resolved measurements track changes in terahertz response over time, allowing engineers to examine dynamic behavior rather than only steady spectral features. This capability is especially relevant to carrier dynamics in semiconductors, where the measured response can reveal how material behavior evolves after excitation. The result is temporal information that complements composition and structural characterization.
A typical workflow uses ultrashort laser pulses to generate and detect a terahertz electric-field transient from the material. The recorded time-dependent signal is converted into a frequency spectrum, which is examined for absorption, reflection, and refractive-index features. Engineers compare these responses across samples or regions to assess composition, structure, or material behavior.
The method supports characterization of semiconductors, polymers, pharmaceuticals, coatings, and composite materials. Its noninvasive measurements can also support terahertz imaging for nondestructive inspection, including evaluation of defects and layer thickness. These capabilities make it useful when engineers need material information or structural assessment without damaging the component or sample.
Spectroscopic measurements provide frequency-dependent material responses, while imaging maps those responses across a sample or component. This combination can help locate defects and evaluate layer thickness without destructive sectioning. For engineering studies, spatial information from imaging adds practical context to spectral features, supporting inspection of coatings, composites, and other layered or heterogeneous materials.
Semiconductors can be examined through both their spectral response and their time-dependent carrier behavior. Terahertz measurements may reveal features associated with charge transport, while time-resolved approaches follow carrier dynamics as they evolve. This combination helps engineers connect electromagnetic measurements with semiconductor performance and supports characterization that extends beyond composition alone.