Terahertz Spectroscopy

Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA.
Analytical Chemistry (Impact Factor: 5.64). 06/2011; 83(12):4342-68. DOI: 10.1021/ac200907z
Source: PubMed
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    • "The situation has radically changed since the introduction of THz Time-Domain-Spectroscopy (TDS) systems based on femtosecond laser pulses and ultrafast photoconductors manufactured from semiconductors with subpicosecond carrier lifetimes [1]. Half-cycle electrical pulses with the wavelengths in far-infrared (THz pulses) used in these optoelectronic systems provided unprecedented insights into the nature of electron dynamics in semiconductors, vibrations of organic molecules, protein kinetics, etc., [2] [3]. "
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    ABSTRACT: Several applications of terahertz radiation pulses for characterizing semiconductor bulk materials and structures are described. Terahertz pulses emitted at the surfaces illuminated by femtosecond laser of a tunable wavelength are demonstrated to provide information on the electron energy spectrum in the conduction band as well as on the subsurface band bending. On the other hand, by sampling the conductivity of various structures with short electrical field transient photoexcited electron dynamics can be directly studied at its initial, subpicosecond time scale. Narrow gap semiconductors InSb and InAs as well as novel materials such as GaAsBi or self-assembled InAs quantum dots were characterized by using terahertz radiation pulses.
    Proceedings of SPIE - The International Society for Optical Engineering 10/2012; DOI:10.1117/12.929130 · 0.20 Impact Factor
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    ABSTRACT: Measuring the full polarization state of radiation in terahertz time-domain spectroscopy has allowed scientists to study a number of complex dielectric anisotropic properties of materials that could not be easily measured before. Novel polarization sensitive photoconductive detectors have simplified this task and their development has been a significant challenge. In this review I will present some of these devices and will also discuss some of the most recent studies that involve the use of polarization resolved terahertz spectroscopy. KeywordsPhotoconductive–Polarization–Anisotropic–Terahertz–THz–Spectroscopy
    Journal of infrared, millimeter and terahertz waves 04/2011; 33(4):418-430. DOI:10.1007/s10762-011-9856-8 · 1.94 Impact Factor
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    ABSTRACT: Advances in ultrafast lasers and semiconductor technologies have facilitated access to the terahertz (THz) frequency range for spectroscopic and imaging purposes. THz time-domain spectroscopy (TDS) is commonly used to acquire spectral data having high signal-to-noise ratios (SNRs) over a broad range of THz frequencies. THz-TDS instrumentation is commercially available, thereby enabling novel applications of THz time-domain (TD) imaging and spectroscopy in a myriad of applications. This review gives a general description of the instrumentation available for collecting THz-TD data and focuses on measurements of solid samples. Measurement geometries useful for collecting THz-TD data from solid samples are reviewed and a summary is presented of the major applications to the analysis of solid samples related to security issues, as well as samples originating from the pharmaceutical industry, dental sciences, biological samples, and polymer materials. Emphasis is also given to analytical applications in a discussion of the analytical challenges met in quantification of solid analytes by THz-TDS methods.
    Applied Spectroscopy Reviews 11/2011; 46(8-8):636-679. DOI:10.1080/05704928.2011.614305 · 4.27 Impact Factor
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