Journal articles: 'Terahertz gas phase spectroscopy'

1

Smith, Ryan M., and Mark A. Arnold. "Selectivity of Terahertz Gas-Phase Spectroscopy." Analytical Chemistry 87, no. 21 (October 15, 2015): 10679–83. http://dx.doi.org/10.1021/acs.analchem.5b03028.

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Lu, Jian, Yaqing Zhang, Harold Y. Hwang, Benjamin K. Ofori-Okai, Sharly Fleischer, and Keith A. Nelson. "Nonlinear two-dimensional terahertz photon echo and rotational spectroscopy in the gas phase." Proceedings of the National Academy of Sciences 113, no. 42 (October 4, 2016): 11800–11805. http://dx.doi.org/10.1073/pnas.1609558113.

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Ultrafast 2D spectroscopy uses correlated multiple light−matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by multiple terahertz field−dipole interactions. The nonlinear time domain orientation signals are mapped into the frequency domain in 2D rotational spectra that reveal J-state-resolved nonlinear rotational dynamics. The approach enables direct observation of correlated rotational transitions and may reveal rotational coupling and relaxation pathways in the ground electronic and vibrational state.

3

Kilcullen, Patrick, I. D. Hartley, E. T. Jensen, and M. Reid. "Terahertz Time Domain Gas-phase Spectroscopy of Carbon Monoxide." Journal of Infrared, Millimeter, and Terahertz Waves 36, no. 4 (January 16, 2015): 380–89. http://dx.doi.org/10.1007/s10762-014-0139-z.

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Hindle, Francis, Lotta Kuuliala, Meriem Mouelhi, Arnaud Cuisset, Cédric Bray, Mathias Vanwolleghem, Frank Devlieghere, Gaël Mouret, and Robin Bocquet. "Monitoring of food spoilage by high resolution THz analysis." Analyst 143, no. 22 (2018): 5536–44. http://dx.doi.org/10.1039/c8an01180j.

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High resolution rotational Terahertz (THz) spectroscopy is suited to studies of numerous polar gas phase molecules, and particularly volatile organic compounds (VOCs). Analysis of the headspace gas of packed Salmon fillets indicates the degree of food spoilage.

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Neumaier, P. F. X., K. Schmalz, J. Borngräber, R. Wylde, and H. W. Hübers. "Terahertz gas-phase spectroscopy: chemometrics for security and medical applications." Analyst 140, no. 1 (2015): 213–22. http://dx.doi.org/10.1039/c4an01570c.

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Vogt, Dominik Walter, Angus Harvey Jones, and Rainer Leonhardt. "Terahertz Gas-Phase Spectroscopy Using a Sub-Wavelength Thick Ultrahigh-Q Microresonator." Sensors 20, no. 10 (May 25, 2020): 3005. http://dx.doi.org/10.3390/s20103005.

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The terahertz spectrum provides tremendous opportunities for broadband gas-phase spectroscopy, as numerous molecules exhibit strong fundamental resonances in the THz frequency range. However, cutting-edge THz gas-phase spectrometer require cumbersome multi-pass gas cells to reach sufficient sensitivity for trace level gas detection. Here, we report on the first demonstration of a THz gas-phase spectrometer using a sub-wavelength thick ultrahigh-Q THz disc microresonator. Leveraging the microresonator’s ultrahigh quality factor in excess of 120,000 as well as the intrinsically large evanescent field, allows for the implementation of a very compact spectrometer without the need for complex multi-pass gas cells. Water vapour concentrations as low as 4 parts per million at atmospheric conditions have been readily detected in proof-of-concept experiments.

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Hindle, Francis, Robin Bocquet, Anastasiia Pienkina, Arnaud Cuisset, and Gaël Mouret. "Terahertz gas phase spectroscopy using a high-finesse Fabry–Pérot cavity." Optica 6, no. 12 (November 21, 2019): 1449. http://dx.doi.org/10.1364/optica.6.001449.

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Burmistrov E. R. and Avakyants L. P. "Determination of 2DEG parameters in LED heterostructures with three quantum wells In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N/GaN by terahertz time-domain spectroscopy (THz-TDs)." Physics of the Solid State 65, no. 2 (2023): 179. http://dx.doi.org/10.21883/pss.2023.02.55399.503.

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Terahertz time-domain spectroscopy (THz-TDs) has been used to record the resonant frequencies of plasmon oscillations excited in samples of heterostructures with three InxGa1-xN/GaN quantum wells (QWs) by laser pulses with a duration of 130 fs in the temperature range from 90 to 170 K. Fast Fourier transform (FFT) of the time dependence of the electric field of THz-pulses made it possible to obtain the frequency spectra of the power and phase shift of THz-radiation, the interpretation of which made it possible to estimate the pulse relaxation time, mobility and effective mass of two-dimensional electron gas (2DEG) in the heterostructures. Using a series of frequency spectra of the power and phase shift of THz-radiation, the temperature dependences of the effective mass and relaxation time of the 2DEG pulse were obtained. Mobility value 2DEG obtained by the THz-TDs is in good agreement with the data of Hall measurements. Keywords: heterostructures, pulse relaxation time, 2DEG, terahertz radiation, terahertz spectroscopy.

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Mihrin, D., P. W. Jakobsen, A. Voute, L. Manceron, and R. Wugt Larsen. "High-resolution synchrotron terahertz investigation of the large-amplitude hydrogen bond librational band of (HCN)2." Physical Chemistry Chemical Physics 20, no. 12 (2018): 8241–46. http://dx.doi.org/10.1039/c7cp08412a.

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The high-resolution terahertz absorption spectrum of the large-amplitude intermolecular donor librational band ν18 of the homodimer (HCN)₂ has been recorded by means of long-path static gas-phase Fourier transform spectroscopy at 207 K employing a highly brilliant electron storage ring source.

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Бурмистров, Е. Р., and Л. П. Авакянц. "Исследование параметров двумерного электронного газа в квантовых ямах InGaN/GaN методом терагерцового плазмонного резонанса." Физика и техника полупроводников 55, no. 11 (2021): 1059. http://dx.doi.org/10.21883/ftp.2021.11.51561.9685.

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A new approach to determining the parameters of a two-dimensional electron gas in InGaN/GaN quantum wells is proposed. It is based on the method of terahertz spectroscopy with time resolution, within the framework of which the terahertz frequencies of two-dimensional plasmon resonances excited in the studied samples of InGaN/AlGaN/GaN heterostructures by femtosecond laser pulses at a wavelength of 797 nm were recorded. Oscillating behavior of the output terahertz radiation power with minima in the frequency range 1−5 THz is shown, which is associated with the excitation of plasmon oscillations in a two-dimensional electron gas localized in an InGaN/GaN quantum well. During the processing of terahertz spectra, the effect of renormalization of the effective mass of two-dimensional electron gas, as well as phase modulation near the frequencies of plasmon resonances with an increase in the temperature of the sample from 90 to 170 K, was found. The proposed method is non-contact and can be used in a wide temperature range.

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Burmistrov, E. R., and L. P. Avakyants. "Teragertsevaya spektroskopiya s vremennym razresheniem (THZ–TDS) svetodiodnykh geterostruktur s tremya i pyat'yu kvantovymiyamami InxGa1−xN/GaN." Журнал экспериментальной и теоретической физики 163, no. 5 (May 15, 2023): 669–81. http://dx.doi.org/10.31857/s0044451023050061.

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Using terahertz time-domain spectroscopy (THz-TDS), we have detected resonance frequencies of plasmon oscillations excited in heterostructures with multiple InxGa1 – xN/GaN quantum wells by laser pulses with a duration of 130 fs in the temperature range from 90 to 170 K. The fast Fourier transform of temporal forms of terahertz pulses has made it possible to obtain frequency spectra of the power and of the phase shift of terahertz radiation, the interpretation of which has allowed us to estimate the quasi-momentum relaxation time (τ = 10–12 s), mobility (μ = 4 × 103 cm2/(V s)), and effective mass (m* = 0.45m) of majority charge carriers in these heterostructures. Based on the frequency spectra of power and phase shift of terahertz radiation, we have obtained the temperature dependences of the effective mass and relaxation time of the quasi-momentum of a 2D electron gas (2DEG). The 2DEG mobility value obtained by the THz-TDS method is in good agreement with the Hall measurement data.

12

McElroy, Richard, and Klaas Wynne. "Time-Resolved Terahertz Spectroscopy of Condensed Phase Reactions." Laser Chemistry 19, no. 1-4 (January 1, 1999): 145–48. http://dx.doi.org/10.1155/1999/85151.

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Ultrafast time-resolved visible-pump, far-IR (THz) probe spectroscopy has been developed in our lab and has been applied to study carrier dynamics in photoexcited GaAs and dipole solvation dynamics in betaine and p-nitroaniline. This type of spectroscopy enables us to study for the first time the nonequilibrium interaction between excited electronic states and low frequency vibrational modes.

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Hübers, H. W., S. G. Pavlov, H. Richter, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, and D. A. Ritchie. "High-resolution gas phase spectroscopy with a distributed feedback terahertz quantum cascade laser." Applied Physics Letters 89, no. 6 (August 7, 2006): 061115. http://dx.doi.org/10.1063/1.2335803.

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Li, Zhijie, Nick Rothbart, Xiaojiao Deng, Hua Geng, Xiaoping Zheng, Philipp Neumaier, and Heinz-Wilhelm Hübers. "Qualitative and quantitative analysis of terahertz gas-phase spectroscopy using independent component analysis." Chemometrics and Intelligent Laboratory Systems 206 (November 2020): 104129. http://dx.doi.org/10.1016/j.chemolab.2020.104129.

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Uno, Takeshi, and Hitoshi Tabata. "In situMeasurement of Combustion Gas Using Terahertz Time Domain Spectroscopy Setup for Gas Phase Spectroscopy and Measurement of Solid Sample." Japanese Journal of Applied Physics 49, no. 4 (April 20, 2010): 04DL17. http://dx.doi.org/10.1143/jjap.49.04dl17.

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Chul Kim, Ki. "Degradation evaluation of high voltage insulating oils by terahertz spectroscopy." International Journal of Engineering & Technology 7, no. 2.12 (April 3, 2018): 8. http://dx.doi.org/10.14419/ijet.v7i2.12.11025.

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Background/Objectives: The stable electrical power supply is the most important issue for modern industrial society employing various electrical appliance. The power transformer is one of the most important component in the electrical power supply system.Methods/Statistical analysis: The common diagnosis method of insulating oil of transformer is gas-chromatograph. The gas-chromatograph is performed to detect dissolved gas ininsulating oil of transformerduring the stop-period of transformer unit. In this research, the optical properties of insulating oils of transformer (unused new oil, used oil of normal operation, and waste oil of malfunction) are analyzed using a terahertz time-domain spectroscopy in the range of 0.1 ~ 3.0 THz.Findings: The new insulating oil is colorless and transparent. The used insulating oil and waste insulating oil exhibit dark yellow and brown color. The THz sample pulses are delayed of phase and reduced of amplitude compare to passing through the free space. The reduce of amplitude is attributed to increasing of absorption due to aging effect of oils. The refractive index and absorption coefficient of insulating oils are calculated from measured THz pulses. The refractive index of ‘new or used oil’ exhibits a constant value of 1.455 and 1.463 in the full frequency range. But refractive index of ‘waste oil’ exhibits various values of 1.466 ~ 1.485 with the frequency, which is relatively high. The normalized amplitude of waste insulating oil is reduced. The absorption coefficient of waste insulating oil is increased linearly with the increase of frequency. The reducing of THz amplitude is attributed to increase of absorption due to aging effect of oils.Improvements/Applications: The aging effect of insulating oils of transformer is characterized by the portable THz-TDS system. It can be applied to in situ monitoring of insulating oil conditions.

17

Wang, Lan, Yaxin Zhang, Xiaoqing Guo, Ting Chen, Huajie Liang, Xiaolin Hao, Xu Hou, et al. "A Review of THz Modulators with Dynamic Tunable Metasurfaces." Nanomaterials 9, no. 7 (July 1, 2019): 965. http://dx.doi.org/10.3390/nano9070965.

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Terahertz (THz) radiation has received much attention during the past few decades for its potential applications in various fields, such as spectroscopy, imaging, and wireless communications. To use terahertz waves for data transmission in different application systems, the efficient and rapid modulation of terahertz waves is required and has become an in-depth research topic. Since the turn of the century, research on metasurfaces has rapidly developed, and the scope of novel functions and operating frequency ranges has been substantially expanded, especially in the terahertz range. The combination of metasurfaces and semiconductors has facilitated both new opportunities for the development of dynamic THz functional devices and significant achievements in THz modulators. This paper provides an overview of THz modulators based on different kinds of dynamic tunable metasurfaces combined with semiconductors, two-dimensional electron gas heterostructures, superconductors, phase-transition materials, graphene, and other 2D material. Based on the overview, a brief discussion with perspectives will be presented. We hope that this review will help more researchers learn about the recent developments and challenges of THz modulators and contribute to this field.

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Withayachumnankul, Withawat, Bernd M. Fischer, and Derek Abbott. "Numerical removal of water vapour effects from terahertz time-domain spectroscopy measurements." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2097 (May 6, 2008): 2435–56. http://dx.doi.org/10.1098/rspa.2007.0294.

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The use of T-rays, or terahertz radiation, to identify substances by their spectroscopic fingerprints is a rapidly moving field. The dominant approach is presently terahertz time-domain spectroscopy. However, a key problem is that ambient water vapour is ubiquitous and the consequent water absorption distorts the T-ray pulses. Water molecules in the gas phase selectively absorb incident T-rays at discrete frequencies corresponding to their molecular rotational transitions. When T-rays propagate through an atmosphere, this results in prominent resonances spread over the T-ray spectrum; furthermore, in the time domain, fluctuations after the main pulse are observed in the T-ray signal. These effects are generally undesired, since they may mask critical spectroscopic data. So, ambient water vapour is commonly removed from the T-ray path by using a closed chamber during the measurement. Yet, in some applications, a closed chamber is not always feasible. This situation, therefore, motivates the need for an optional alternative method for reducing these unwanted artefacts. This paper represents a study on a computational means that is a step towards addressing the problem arising from water vapour absorption over a moderate propagation distance. Initially, the complex frequency response of water vapour is modelled from a spectroscopic catalogue. Using a deconvolution technique, together with fine tuning of the strength of each resonance, parts of the water vapour response are removed from a measured T-ray signal, with minimal signal distortion, thus providing experimental validation of the technique.

19

Miao, Xinyang, Jing Zhu, Kun Zhao, Honglei Zhan, and Wenzheng Yue. "Determining the Humidity-Dependent Ortho-to-Para Ratio of Water Vapor at Room Temperature Using Terahertz Spectroscopy." Applied Spectroscopy 72, no. 7 (June 12, 2018): 1040–46. http://dx.doi.org/10.1177/0003702818772853.

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The origin of the water spin isomers observed under various physico-chemical conditions is of great interest, including that of H2O molecules in the gas phase. Here, terahertz time-domain spectroscopy (THz-TDS) was used to study the humidity-dependent ortho-to- para (O/P) ratio of water vapor at room temperature. The relative contents of para and ortho molecules were obtained by fitting the absorption lines of water vapor showing the relationship between the spin isomer contents and humidity. Larger O/P ratios with values of ∼3.2 were observed at lower humidity (<20%) due to the stronger attractive forces of para molecules. The concentration of the ortho isomers then began to decrease at higher humidity (>20%) due to the preferential formation of dimers and clusters at increasing concentrations. Thus, the ratio gradually decreased with increasing humidity.

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Бурмистров, Е. Р., and Л. П. Авакянц. "Определение параметров 2ДЭГ в светодиодных гетероструктурах с тремя квантовыми ямами In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N/GaN методом терагерцевой спектроскопии с временным разрешением (THz-TDs)." Физика твердого тела 65, no. 2 (2023): 185. http://dx.doi.org/10.21883/ftt.2023.02.54289.503.

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Terahertz time-domain spectroscopy (THz-TDs) has been used to record the resonant frequencies of plasmon oscillations excited in samples of heterostructures with three InGaN/GaN quantum wells (QWs) by laser pulses with a duration of 130 fs in the temperature range from 90 to 170 K. Fast Fourier transform (FFT) of the time dependence of the electric field of THz pulses made it possible to obtain the frequency spectra of the power and phase shift of THz radiation, the interpretation of which made it possible to estimate the pulse relaxation time, mobility and effective mass of two-dimensional electron gas (2DEG) in the heterostructures. Using a series of frequency spectra of the power and phase shift of THz radiation, the temperature dependences of the effective mass and relaxation time of the 2DEG pulse were obtained. Mobility value 2DEG obtained by the THz-TDs is in good agreement with the data of Hall measurements.

21

Yasui, Takeshi, Kohji Kawamoto, Yi-Da Hsieh, Yoshiyuki Sakaguchi, Mukesh Jewariya, Hajime Inaba, Kaoru Minoshima, Francis Hindle, and Tsutomu Araki. "Enhancement of spectral resolution and accuracy in asynchronous-optical-sampling terahertz time-domain spectroscopy for low-pressure gas-phase analysis." Optics Express 20, no. 14 (June 20, 2012): 15071. http://dx.doi.org/10.1364/oe.20.015071.

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Yian Liu, Zhiyao Huang, Haifeng Ji, and Haiqing Li. "Solid Volume Fraction Measurement of Gas–Solid Two-Phase Flow Based on Terahertz Time-Domain Spectroscopy Technique: A Preliminary Study and Static Experimental Results." IEEE Transactions on Instrumentation and Measurement 58, no. 5 (May 2009): 1585–91. http://dx.doi.org/10.1109/tim.2008.2009202.

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Zavjalov, A. P., G. A. Lyubas, M. R. Sharafutdinov, V. V. Kriventsov, and D. Yu Kosyanov. "Application of Some Techniques Using Synchrotron Radiation to the Study of a Promising Composite Thermoelectric Material SrTiO<sub>3</sub>–TiO<sub>2</sub>." Поверхность. Рентгеновские, синхротронные и нейтронные исследования, no. 6 (June 1, 2023): 21–26. http://dx.doi.org/10.31857/s1028096023060183.

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The results of a study of biphase ceramics SrTiO3–TiO2, previously proposed as a promising n-type thermoelectric material, obtained using synchrotron radiation techniques at the shared research center “Siberian Synchrotron and Terahertz Radiation Center”, are presented. In particular, it has been demonstrated by in-situ heating X-ray diffraction that the reaction between the powder components SrCO3 (strontianite) and TiO2 (anatase) to obtain SrTiO3 (tausonite) is not the driving force in the preparation of ceramics by spark plasma sintering of the reaction mixture. For two spectral methods – X-ray luminescence and XANES spectroscopy, the spectrum of biphasic ceramics was compared with a model spectrum obtained from the spectra of single-phase ceramics as reference samples. The X-ray luminescence method revealed a shift to the high-energy region and a narrowing of the spectrum of biphase ceramics, which may indicate size quantization (the presence of a two-dimensional electron gas) in the system. Changes were found in the XANES spectrum of biphase ceramics in the region in which its shape can significantly depend on the symmetry of the nearest environment of Ti4+ atoms. However, it is difficult to interpret these data without numerical simulation.

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Smirnova, I. N., A. Cuisset, F. Hindle, G. Mouret, R. Bocquet, O. Pirali, and P. Roy. "Gas-Phase Synchrotron FTIR Spectroscopy of Weakly Volatile Alkyl Phosphonate and Alkyl Phosphate Compounds: Vibrational and Conformational Analysis in the Terahertz/Far-IR Spectral Domain." Journal of Physical Chemistry B 114, no. 50 (December 23, 2010): 16936–47. http://dx.doi.org/10.1021/jp108421c.

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Gerasymov, Oleg I., and Liudmyla M. Sidletska. "Diagnosis of inhomogeneous one-dimensional discrete chains by photon scattering." Environmental safety and natural resources 41, no. 1 (April 15, 2022): 102–10. http://dx.doi.org/10.32347/2411-4049.2022.1.102-110.

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Among the ways to reduce radiation doses (increasing the distance from the source to the person, reducing the time spent in radiation fields, reducing the radiation dose rate of the source) an important role is played by shielding the source of ionizing radiation.Currently, the use of screens is limited by the small selection of materials and the inconvenience of their use, which complicates their operation, installation and replacement, or disassembly.The propagation of a plane wave in a one-dimensional force chain with Hertzian contacts is analyzed in a linear approximation for cases with the presence of incorporated single and double impurities (defects). The algorithm of analytical solution of control equations and finding of reflection and transmission coefficients of incident radiation is determined. In terms of phase shifts, the frequency criterion of multi-modes of generation of transparent modes for inhomogeneous chains (with double impurities) similar to the Ramsauer-Townsend effect in the scattering of electrons by inert gas atoms is established. The obtained theoretical results are consistent with the data obtained from alternative sources. Possibilities of application of terahertz spectroscopy of radiation transmission for structural diagnostics and detection of in homogeneities, impurities and defects in discrete micro-mechanical (granular) systems are discussed. In particular, preliminary experimental data on scattering of terahertz radiation on samples of granular materials with different degrees of packing, from low to densely packed, which clearly indicate the dependence of the transmittance on the degree of packing and the formation of the corresponding band structure of spectra. The obtained results are also discussed in terms of applications to the creation of the element base of photonic circuitry in the sub millimeter range using decorated with impurities and structured low-dimensional discrete power circuits.

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Wiesemeyer, H., R. Güsten, K. M. Menten, C. A. Durán, T. Csengeri, A. M. Jacob, R. Simon, J. Stutzki, and F. Wyrowski. "Unveiling the chemistry of interstellar CH." Astronomy & Astrophysics 612 (April 2018): A37. http://dx.doi.org/10.1051/0004-6361/201731810.

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Context. The methylidyne radical CH is commonly used as a proxy for molecular hydrogen in the cold, neutral phase of the interstellar medium. The optical spectroscopy of CH is limited by interstellar extinction, whereas far-infrared observations provide an integral view through the Galaxy. While the HF ground state absorption, another H2 proxy in diffuse gas, frequently suffers from saturation, CH remains transparent both in spiral-arm crossings and high-mass star forming regions, turning this light hydride into a universal surrogate for H2. However, in slow shocks and in regions dissipating turbulence its abundance is expected to be enhanced by an endothermic production path, and the idea of a “canonical” CH abundance needs to be addressed. Aim. The N = 2 ← 1 ground state transition of CH at λ149 μm has become accessible to high-resolution spectroscopy thanks to the German Receiver for Astronomy at Terahertz Frequencies (GREAT) aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). Its unsaturated absorption and the absence of emission from the star forming regions makes it an ideal candidate for the determination of column densities with a minimum of assumptions. Here we present an analysis of four sightlines towards distant Galactic star forming regions, whose hot cores emit a strong far-infrared dust continuum serving as background signal. Moreover, if combined with the sub-millimeter line of CH at λ560 μm , environments forming massive stars can be analyzed. For this we present a case study on the “proto-Trapezium” cluster W3 IRS5. Methods. While we confirm the global correlation between the column densities of HF and those of CH, both in arm and interarm regions, clear signposts of an over-abundance of CH are observed towards lower densities. However, a significant correlation between the column densities of CH and HF remains. A characterization of the hot cores in the W3 IRS5 proto-cluster and its envelope demonstrates that the sub-millimeter/far-infrared lines of CH reliably trace not only diffuse but also dense, molecular gas. Results. In diffuse gas, at lower densities a quiescent ion-neutral chemistry alone cannot account for the observed abundance of CH. Unlike the production of HF, for CH+ and CH, vortices forming in turbulent, diffuse gas may be the setting for an enhanced production path. However, CH remains a valuable tracer for molecular gas in environments reaching from diffuse clouds to sites of high-mass star formation.

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Coudert, L. H., L. Margulès, C. Vastel, R. Motiyenko, E. Caux, and J. C. Guillemin. "Astrophysical detections and databases for the mono deuterated species of acetaldehyde CH2DCOH and CH3COD." Astronomy & Astrophysics 624 (April 2019): A70. http://dx.doi.org/10.1051/0004-6361/201834827.

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Context. Detection of deuterated species may provide information on the evolving chemistry in the earliest phases of star-forming regions. For molecules with two isomeric forms of the same isotopic variant, gas-phase and solid-state formation pathways can be differentiated using their abundance ratio. Aims. Spectroscopic databases for astrophysical purposes are built for the two mono deuterated isomeric species CH2DCOH and CH3COD of the complex organic molecule acetaldehyde. These databases can be used to search and detect these two species in astrophysical surveys, retrieving their column density and therefore abundances. Methods. Submillimeter wave and terahertz transitions were measured for mono deuterated acetaldehyde CH2DCOH which is a non-rigid species displaying internal rotation of its asymmetrical CH2D methyl group. An analysis of a dataset consisting of previously measured microwave data and the newly measured transition was carried out with a model accounting for the large amplitude torsion. Results. The frequencies of 2556 transitions are reproduced with a unitless standard deviation of 2.3 yielding various spectroscopic constants. Spectroscopic databases for astrophysical purposes were built for CH2DCOH using the results of the present analysis and for CH3COD using the results of a previous spectroscopic investigation. These two species were both searched for and are detected toward a low-mass star-forming region. Conclusions. We report the first detection of CH2DCOH (93 transitions) and the detection of CH3COD (43 transitions) species in source B of the IRAS 16293−2422 young stellar binary system located in the ρ Ophiuchus cloud region, using the publicly available ALMA Protostellar Interferometric Line Survey.

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Van der Weide, D. W., J. Murakowski, and F. Keilmann. "Gas-absorption spectroscopy with electronic terahertz techniques." IEEE Transactions on Microwave Theory and Techniques 48, no. 4 (April 2000): 740–43. http://dx.doi.org/10.1109/22.841967.

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Mittleman, D. M., R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss. "Gas sensing using terahertz time-domain spectroscopy." Applied Physics B: Lasers and Optics 67, no. 3 (September 1, 1998): 379–90. http://dx.doi.org/10.1007/s003400050520.

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Finneran, Ian A., Ralph Welsch, Marco A. Allodi, Thomas F. Miller, and Geoffrey A. Blake. "Coherent two-dimensional terahertz-terahertz-Raman spectroscopy." Proceedings of the National Academy of Sciences 113, no. 25 (June 6, 2016): 6857–61. http://dx.doi.org/10.1073/pnas.1605631113.

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We present 2D terahertz-terahertz-Raman (2D TTR) spectroscopy, the first technique, to our knowledge, to interrogate a liquid with multiple pulses of terahertz (THz) light. This hybrid approach isolates nonlinear signatures in isotropic media, and is sensitive to the coupling and anharmonicity of thermally activated THz modes that play a central role in liquid-phase chemistry. Specifically, by varying the timing between two intense THz pulses, we control the orientational alignment of molecules in a liquid, and nonlinearly excite vibrational coherences. A comparison of experimental and simulated 2D TTR spectra of bromoform (CHBr3), carbon tetrachloride (CCl4), and dibromodichloromethane (CBr2Cl2) shows previously unobserved off-diagonal anharmonic coupling between thermally populated vibrational modes.

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Reuter, M., N. Vieweg, M. Koch, and I. Dierking. "Terahertz spectroscopy across liquid crystalline phase transitions." Applied Physics Letters 108, no. 5 (February 2016): 051908. http://dx.doi.org/10.1063/1.4941666.

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32

Pashkin, A., M. Kempa, H. Němec, F. Kadlec, and P. Kužel. "Phase-sensitive time-domain terahertz reflection spectroscopy." Review of Scientific Instruments 74, no. 11 (November 2003): 4711–17. http://dx.doi.org/10.1063/1.1614878.

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33

LIU, JINGLE, JIANMING DAI, XIAOFEI LU, I.-CHEN HO, and X. C. ZHANG. "BROADBAND TERAHERTZ WAVE GENERATION, DETECTION AND COHERENT CONTROL USING TERAHERTZ GAS PHOTONICS." International Journal of High Speed Electronics and Systems 20, no. 01 (March 2011): 3–12. http://dx.doi.org/10.1142/s0129156411006350.

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Terahertz (THz) gas photonics uses gas as THz emitter and sensor for time-domain spectroscopy. Unique properties of the gas promise scalable, strong THz wave generation with broad spectral range covering the entire THz gas (0.3 THz to 35 THz). The systematic study of THz wave generation and detection in different gases shows that the generation efficiency is monotonically decreasing with the ionization potential of the gas molecules while the detection efficiency is linearly proportional to the third order nonlinear coefficient of the gas molecules. We also discuss the development of THz wave detection using laser-induced fluorescence and coherent control with THz gas photonics.

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Katagiri, Takashi, Takahiro Suzuki, and Yuji Matsuura. "Time-domain terahertz gas spectroscopy using hollow-optical-fiber gas cell." Optical Engineering 57, no. 05 (May 12, 2018): 1. http://dx.doi.org/10.1117/1.oe.57.5.054104.

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35

Jameson, Cynthia J. "Gas-phase NMR spectroscopy." Chemical Reviews 91, no. 7 (November 1991): 1375–95. http://dx.doi.org/10.1021/cr00007a005.

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36

SUAREZ, CRISTINA. "Gas-Phase NMR Spectroscopy." Chemical Educator 3, no. 2 (April 1998): 1–18. http://dx.doi.org/10.1007/s00897980202a.

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37

Lu, Xiaofei, and Xi-Cheng Zhang. "Investigation of ultra-broadband terahertz time-domain spectroscopy with terahertz wave gas photonics." Frontiers of Optoelectronics 7, no. 2 (December 19, 2013): 121–55. http://dx.doi.org/10.1007/s12200-013-0371-5.

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38

Gerecht, Eyal, Kevin O. Douglass, and David F. Plusquellic. "Chirped-pulse terahertz spectroscopy for broadband trace gas sensing." Optics Express 19, no. 9 (April 22, 2011): 8973. http://dx.doi.org/10.1364/oe.19.008973.

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39

Takeya, Kei, Caihong Zhang, Iwao Kawayama, Hironaru Murakami, Peter Uhd Jepsen, Jian Chen, Peiheng Wu, Kazunari Ohgaki, and Masayoshi Tonouchi. "Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates." Applied Physics Express 2, no. 12 (December 4, 2009): 122303. http://dx.doi.org/10.1143/apex.2.122303.

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40

Sitnikov, D. S., S. A. Romashevskiy, A. A. Pronkin, and I. V. Ilina. "Open-path gas detection using terahertz time-domain spectroscopy." Journal of Physics: Conference Series 1147 (January 2019): 012061. http://dx.doi.org/10.1088/1742-6596/1147/1/012061.

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41

Sinyukov, Alexander M., Zhiwei Liu, Yew Li Hor, Ke Su, Robert B. Barat, Dale E. Gary, Zoi-Heleni Michalopoulou, Ivan Zorych, John F. Federici, and David Zimdars. "Rapid-phase modulation of terahertz radiation for high-speed terahertz imaging and spectroscopy." Optics Letters 33, no. 14 (July 11, 2008): 1593. http://dx.doi.org/10.1364/ol.33.001593.

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42

Chevalier, Paul, Arman Amirzhan, Fan Wang, Marco Piccardo, Steven G. Johnson, Federico Capasso, and Henry O. Everitt. "Widely tunable compact terahertz gas lasers." Science 366, no. 6467 (November 14, 2019): 856–60. http://dx.doi.org/10.1126/science.aay8683.

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The terahertz region of the electromagnetic spectrum has been the least utilized owing to inadequacies of available sources. We introduce a compact, widely frequency-tunable, extremely bright source of terahertz radiation: a gas-phase molecular laser based on rotational population inversions optically pumped by a quantum cascade laser. By identifying the essential parameters that determine the suitability of a molecule for a terahertz laser, almost any rotational transition of almost any molecular gas can be made to lase. Nitrous oxide is used to illustrate the broad tunability over 37 lines spanning 0.251 to 0.955 terahertz, each with kilohertz linewidths. Our analysis shows that laser lines spanning more than 1 terahertz with powers greater than 1 milliwatt are possible from many molecular gases pumped by quantum cascade lasers.

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Crozet, P., A. J. Ross, and M. Vervloet. "3 Gas-phase molecular spectroscopy." Annu. Rep. Prog. Chem., Sect. C: Phys. Chem. 98 (2002): 33–86. http://dx.doi.org/10.1039/b201321p.

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44

Reimann, Klaus, Michael Woerner, and Thomas Elsaesser. "Two-dimensional terahertz spectroscopy of condensed-phase molecular systems." Journal of Chemical Physics 154, no. 12 (March 28, 2021): 120901. http://dx.doi.org/10.1063/5.0046664.

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45

Chau, K. J., K. M. Rieckmann, and A. Y. Elezzabi. "Metallic phase transition investigated via terahertz time-domain spectroscopy." Applied Physics Letters 90, no. 4 (January 22, 2007): 041920. http://dx.doi.org/10.1063/1.2432299.

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Zhong, Hua, Cunlin Zhang, Liangliang Zhang, Yuejin Zhao, and Xi-Cheng Zhang. "A phase feature extraction technique for terahertz reflection spectroscopy." Applied Physics Letters 92, no. 22 (June 2, 2008): 221106. http://dx.doi.org/10.1063/1.2938055.

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KARPOWICZ, NICHOLAS, JIANMING DAI, X. C. ZHANG, LIANGLIANG ZHANG, and CUNLIN ZHANG. "RECENT DEVELOPMENTS IN BROADBAND TERAHERTZ SPECTROSCOPY." International Journal of High Speed Electronics and Systems 18, no. 04 (December 2008): 1005–12. http://dx.doi.org/10.1142/s0129156408005953.

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Terahertz time-domain measurements using air as the emission and detection medium are shown to enable broadband spectroscopy with continuous coverage of the entire terahertz band, from 0.1 to over 10 THz. It is shown that the unique properties of using a gaseous medium allow for excellent phase matching without interruptions from crystalline phonon modes or antenna resonant structures from conventional solid state emitters and sensors, allowing the full bandwidth of the laser pulse to be used. It is also shown that the limiting factor on the system bandwidth is the temporal profile of the probe pulse used for detection, and how modification of this profile can further enhance the detection bandwidth.

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Wang, Fan, Jeongwon Lee, Dane J. Phillips, Samuel G. Holliday, Song-Liang Chua, Jorge Bravo-Abad, John D. Joannopoulos, Marin Soljačić, Steven G. Johnson, and Henry O. Everitt. "A high-efficiency regime for gas-phase terahertz lasers." Proceedings of the National Academy of Sciences 115, no. 26 (June 11, 2018): 6614–19. http://dx.doi.org/10.1073/pnas.1803261115.

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We present both an innovative theoretical model and an experimental validation of a molecular gas optically pumped far-infrared (OPFIR) laser at 0.25 THz that exhibits 10× greater efficiency (39% of the Manley–Rowe limit) and 1,000× smaller volume than comparable commercial lasers. Unlike previous OPFIR-laser models involving only a few energy levels that failed even qualitatively to match experiments at high pressures, our ab initio theory matches experiments quantitatively, within experimental uncertainties with no free parameters, by accurately capturing the interplay of millions of degrees of freedom in the laser. We show that previous OPFIR lasers were inefficient simply by being too large and that high powers favor high pressures and small cavities. We believe that these results will revive interest in OPFIR laser as a powerful and compact source of terahertz radiation.

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Kamaraju, N., W. Pan, U. Ekenberg, D. M. Gvozdić, S. Boubanga-Tombet, P. C. Upadhya, J. Reno, A. J. Taylor, and R. P. Prasankumar. "Terahertz magneto-optical spectroscopy of a two-dimensional hole gas." Applied Physics Letters 106, no. 3 (January 19, 2015): 031902. http://dx.doi.org/10.1063/1.4906282.

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Yang, Dongxun, Fumikazu Murakami, Shingo Genchi, Hidekazu Tanaka, and Masayoshi Tonouchi. "Noncontact evaluation of the interface potential in VO₂/Si heterojunctions across metal–insulator phase transition." Applied Physics Letters 122, no. 4 (January 23, 2023): 041601. http://dx.doi.org/10.1063/5.0136610.

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This study conducted laser-induced terahertz emission spectroscopy on a VO2/Si heterojunction. Consequently, rapid estimation of the local interface potential was realized and the work function of VO2 was obtained as 5.17–5.25 eV with increasing temperature from 320 to 380 K. Moreover, an obvious terahertz emission variation was observed across the metal–insulator phase transition of VO2, and the doping conditions of the Si substrate largely influenced the terahertz emission. These results imply a strong relationship between the terahertz emission amplitude and the interface electric field, which supports the rapid performance of terahertz emission spectroscopy in estimating the work function of VO2.

Journal articles on the topic 'Terahertz gas phase spectroscopy'

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