Two-Dimensional Spectroscopy at Terahertz Frequencies

Lu, Jian; Li, Xian; Zhang, Yaqing; Hwang, Harold Y.; Ofori-Okai, Benjamin K.; Nelson, Keith A.

doi:10.1007/s41061-018-0185-4

Cited by 32 publications

(17 citation statements)

References 102 publications

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“…DSTMS THz emitter crystal was used for generating THz pulses with a high peak electric field of about 300 kV/cm for a system enabling the THz Kerr effect spectroscopy and two-dimensional terahertz-terahertz-Raman spectroscopy [77,187,188], demonstrating a 2D experimental technique for measuring the nonlinear response of liquids in the THz field. The terahertz-terahertz-Raman pulse sequences that are sensitive to intermolecular modes (e.g., molecular orientational alignment) were employed to initiate intramolecular vibrational modes of liquids (see Figure 14).…”

Section: Thz Nonlinear Photonicsmentioning

confidence: 99%

Organic Crystals for THz Photonics

et al. 2019

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Organic crystals with second-order optical nonlinearity feature very high and ultra-fast optical nonlinearities and are therefore attractive for various photonics applications. During the last decade, they have been found particularly attractive for terahertz (THz) photonics. This is mainly due to the very intense and ultra-broadband THz-wave generation possible with these crystals. We review recent progress and challenges in the development of organic crystalline materials for THz-wave generation and detection applications. We discuss their structure, intrinsic properties, and advantages compared to inorganic alternatives. The characteristic properties of the most widely employed organic crystals at present, such as DAST, DSTMS, OH1, HMQ-TMS, and BNA are analyzed and compared. We summarize the most important principles for THz-wave generation and detection, as well as organic THz-system configurations based on either difference-frequency generation or optical rectification. In addition, we give state-of-the-art examples of very intense and ultra-broadband THz systems that rely on organic crystals. Finally, we present some recent breakthrough demonstrations in nonlinear THz photonics enabled by very intense organic crystalline THz sources, as well as examples of THz spectroscopy and THz imaging using organic crystals as THz sources for various scientific and technological applications.

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Section: Thz Nonlinear Photonicsmentioning

confidence: 99%

Organic Crystals for THz Photonics

et al. 2019

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“…MALDI-TOF-MS is a high-throughput technique with high tolerance of salts and some of other interferences, thus has become a preeminent technique for the analysis of complex samples without intensive sample extraction and chromatographic separation [15]. It has been known that medicinal herbs are complex mixtures with hundreds of chemically different constituents.…”

Section: Introductionmentioning

confidence: 99%

MALDI imaging for the localization of saponins in root tissues and rapid differentiation of three Panax herbs

et al. 2016

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The roots of Panax genus with ginseng saponins as bioactive ingredients have been widely used as herbal medicines and food additives. Panax ginseng, Panax quinquefolius, and Panax notoginseng are three major commercial species in Panax genus, with similar morphological appearance but different pharmacological functions. Various methods have been developed and applied for the differentiation of these species. In this work, MALDI-TOF-MS imaging (MSI) was employed for the localization of saponins in root tissues and for the rapid differentiation of the three Panax species for the first time. After a simple sample preparation, MALDI-TOF-MSI analysis of root tissue allowed the detection of 51 saponins. Localization of saponins in the tissue was mapped in ion images, which were obviously related to botanical structure. The localization modes varied with Panax species, providing valuable information for the discrimination of ginseng species. Principal component analysis (PCA) of data collected from areas with abundant saponins based on ion images was applied for the differentiation. Nine characteristic saponin peaks were identified from the PCA analysis. The MALDI-TOF-MSI together with area-specific data analysis provided high potential for the rapid differentiation of Panax herbs.

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“…In general, nonlinear THz spectroscopies, such as optical-pump THz-probe spectroscopy (OPTP) or two dimensional THz spectroscopy, use more than one optical delay line 16 . In OPTP experiments, the difference of the transmitted THz field with and without optical excitation is recorded as a function of both delay lines (THz-probe delay time and pump delay time).…”

Section: Integration Of Rapid Scanning Techniques For Nonlinear Thz Smentioning

confidence: 99%

Integration of a rapid scanning technique into THz time-domain spectrometers for nonlinear THz spectroscopy measurements

2019

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We have implemented a rapid scanning technique into THz time-domain spectrometers using an oscillating frictionless delay line, especially adapted for nonlinear THz experiments. Thereby we were able to increase the dynamic range of THz measurements in the frequency range from 40 to 200 cm -1 by up to 24 dB and reduce the scanning time by up to a factor of 200. We report here test measurements on TDS-setups at repetition rates of 80 MHz and 5 kHz. The dynamic range exceeds 64 dB, which allows to record even small changes in the THz absorption upon optical excitation by a THz probe, covering the frequency range of the intermolecular modes and the phonon bands. We demonstrate the potential of this technique for optical-pump THz-probe experiments using a 70 μm thick high-resistivity silicon, excited by 400 nm, ∼50 fs pulses as a sample.

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Two-Dimensional Spectroscopy at Terahertz Frequencies

Cited by 32 publications

References 102 publications

Organic Crystals for THz Photonics

Organic Crystals for THz Photonics

MALDI imaging for the localization of saponins in root tissues and rapid differentiation of three Panax herbs

Integration of a rapid scanning technique into THz time-domain spectrometers for nonlinear THz spectroscopy measurements

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