Bernd M. Fischer

Bio: Bernd M. Fischer is an academic researcher from University of Marburg. The author has contributed to research in topics: Terahertz radiation & Terahertz spectroscopy and technology. The author has an hindex of 32, co-authored 165 publications receiving 5423 citations. Previous affiliations of Bernd M. Fischer include University of Regensburg & University of Adelaide.

Far-infrared vibrational modes of DNA components studied by terahertz time-domain spectroscopy

Abstract: The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules.

Dynamic range in terahertz time-domain transmission and reflection spectroscopy

Abstract: We present a quantitative method for identification of the dynamic range of the detectable absorption coefficient in the analysis of transmission terahertz (THz) time-domain spectroscopy data. In transmission measurements the largest detectable absorption coefficient is determined by the dynamic range of the THz signals, whereas in reflection measurements the largest detectable absorption coefficient is determined by the scan-to-scan reproducibility of the signal.

Collective vibrational modes in biological molecules investigated by terahertz time-domain spectroscopy

Abstract: We present well-resolved absorption spectra of biological molecules in the far-IR (FIR) spectral region recorded by terahertz time-domain spectroscopy (THz- TDS). As an illustrative example we discuss the absorption spectra of benzoic acid, its monosubstitutes salicylic acid (2-hydroxy-benzoic acid), 3- and 4-hydroxybenzoic acid, and aspirin (acetylsalicylic acid) in the spectral region between 18 and 150 cm 1 . The spectra exhibit distinct features originating from low-frequency vibrational modes caused by intra- or intermolecular collective motion and lattice modes. Due to the collective origin of the observed modes the absorption spectra are highly sensitive to the overall structure and configuration of the molecules, as well as their environment. The THz-TDS procedure can provide a direct fingerprint of the molecular structure or conformational state of a compound. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospec- troscopy) 67: 310 -313, 2002

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Cutting-edge terahertz technology

Abstract: Research into terahertz technology is now receiving increasing attention around the world, and devices exploiting this waveband are set to become increasingly important in a very diverse range of applications. Here, an overview of the status of the technology, its uses and its future prospects are presented.

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

Materials for terahertz science and technology

Abstract: Terahertz spectroscopy systems use far-infrared radiation to extract molecular spectral information in an otherwise inaccessible portion of the electromagnetic spectrum. Materials research is an essential component of modern terahertz systems: novel, higher-power terahertz sources rely heavily on new materials such as quantum cascade structures. At the same time, terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules.

Terahertz spectroscopy and imaging – Modern techniques and applications

Abstract: Over the past three decades a new spectroscopic technique with unique possibilities has emerged. Based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts in the far-infrared, this technique has become known as terahertz time-domain spectroscopy (THz-TDS). In this review article the authors describe the technique in its various implementations for static and time-resolved spectroscopy, and illustrate the performance of the technique with recent examples from solid-state physics and physical chemistry as well as aqueous chemistry. Examples from other fields of research, where THz spectroscopic techniques have proven to be useful research tools, and the potential for industrial applications of THz spectroscopic and imaging techniques are discussed.