Optical constants of CuO and ZnO particles in the terahertz frequency range

 Calvo-de la Rosa, Jaume, Alexandre Locquet, Denis Bouscaud, Sophie Berveiller, and D. S. Citrin. "Optical constants of CuO and ZnO particles in the terahertz frequency range." Ceramics International (2020).

Abstract

The optical constants (complex dielectric function) of CuO and ZnO particles in polyethylene pellets are measured by terahertz time-domain spectroscopy. The determination of the dielectric properties of these materials is of interest for energy-storage applications, for instance. Maxwell-Garnett theory is used to extract the contribution to the frequency-dependent optical constants of the oxide powders. The validity of the assumptions of Maxwell-Garnett theory are experimentally verified and self-consistency of the results of the model confirmed. On this basis, experimental complex permittivity values for isotropic CuO and ZnO oxide powders are reported in the 100 GHz-3 THz range.

for full paper see https://www.sciencedirect.com/science/article/pii/S0272884220318502

"THz transmission data through the pellets were obtained using a TeraView TPS Spectra 3000 in transmission mode. The experimental bandwidth (power spectrum of "

ASSESSMENT METHODS FOR COMPOSITE AEROSPACE STRUCTURES

Summary:
In this paper result of detection and localization of artificially initiated delaminations in small carbon fibre reinforced polymer CFRP and glass fibre reinforced polymers GFRP samples were presented. The first method was electromechanical impedance method (EMI). This method utilizes electromechanical coupling of piezoelectric transducer with host structure. Due to this coupling mechanical resonances of structure can be seen in electrical impedance characteristic of piezoelectric transducer. Instead of electrical impedance other parameters such as resistance, conductance, admittance or susceptance are very often utilized. In the research real part of electrical impedance (resistance) was measured. Delamination in CFRP sample caused frequency shift of certain resonance frequencies visible in resistance characteristic. The second method was a laser vibrometry. It is a noncontact technique that allows to measure vibration of structure excited by piezoelectric transducer. During research standing waves (vibration–based method) and propagating waves (guided waves–based method) were registered for CFRP sample. In the vibration–based method, the frequency shifts of certain resonance frequencies were analyzed. In guided waves-based technique, the interaction of elastic waves with delamination can be seen in the RMS energy map. The third method is Terahertz spectroscopy. The device uses an electromagnetic radiation in the terahertz range (0.1–3 THz). The spectrometer is equipped with moving table that allows for XY scanning of large objects. During research the scanning heads working in reflection mode were utilized and the measurements were taken for GFRP sample with delamination. During research time signals as well as sets of signals creating B–scans and C–scans were analysed. The obtained results showed that the THz spectroscopy technique can detect and visualize delamination between the GFRP layers.

Teraview's TPS Spectra 3000 was used in these investigations

http://www.dem.ist.utl.pt/smart2015/files/SMART_2015_Proceedings/PDF/Papers/SMART2015_053.pdf

TeraPulse - The Next Generation Terahertz Spectrometer and Imaging System from TeraView

TeraView is pleased to announce the launch of its new Terahertz system, the TeraPulse 4000!


Building on the success of the TPS Spectra 3000 which has become the industry standard in Terahertz instrumentation, the TeraPulse 4000 offers the same industry leading performance and reliability, all within a single, compact unit. Smaller, lighter and more portable, the TeraPulse is equally at home in a laboratory or industrial environment.

The system is available with an on-board spectroscopy/imaging compartment (as shown above) or with fibres. The fibre based system can then accept various ’plug and play’ sample modules, enabling a range of different Terahertz applications that have been developed by TeraView over the last decade. Both configurations are fully compatible with TeraView’s existing and extensive range of “plug and play” modules, which allow users to quickly and economically expand their Terahertz capabilities.

The system is also supplied with a new software suite which fully integrates the improved spectroscopic and imaging capabilities of the unit into one common platform.

Dr Don Arnone, TeraView’s CEO stated “TeraPulse represents a substantial investment by TeraView in the future of Terahertz instrumentation, developed with extensive feedback from our customers around the world. It takes all of the reliability, stability and improved performance achieved over the last several years, and puts them into a smaller, lighter package with enhanced capabilities. The TeraPulse 4000 is designed to serve as a versatile core unit which can be configured for a variety of laboratory, production and other industrial applications. We are also planning other exciting additions to the TeraPulse range over the coming months, which come out of our continued commitment to R&D of Terahertz technology as well as close collaborations with our customers and partners. ”

To find out more please visit: www.teraview.com

About TeraView  


TeraView is the world’s first company devoted to the application of Terahertz light for spectroscopy and imaging. A spin out from the Toshiba Corporation and Cambridge University in 2001, the team at TeraView has been developing its technology and products across a number of applications for the last quarter of a century, and is now approaching 100 systems installed in circa 30 countries. TeraView provides both Terahertz instrumentation as well as applications know-how to its customers, encompassed in over 100 peer reviewed scientific publications as well as the largest collection of granted patents on Terahertz technology. Headquartered in Cambridge, sales and support are available throughout Europe, North America and the Far East either directly or through a network of distributors.

Orbital-selective metal–insulator transition and gap formation above TC in superconducting Rb1−xFe2−ySe2

Zhe Wang, M. Schmidt, J. Fischer, V. Tsurkan, M. Greger, D. Vollhardt, A. Loidl & J. Deisenhofer

Abstract

Understanding the origin of high-temperature superconductivity in copper- and iron-based materials is one of the outstanding tasks of current research in condensed matter physics. Even the normal metallic state of these materials exhibits unusual properties. Here we report on a hierarchy of temperatures Tc<Tgap<Tmet in superconducting Rb1−xFe2−ySe2 observed by THz spectroscopy (Tc=critical temperature of the superconducting phase; Tgap=temperature below which an excitation gap opens; Tmet=temperature below which a metallic optical response occurs). Above Tmet=90 K the material reveals semiconducting characteristics. Below Tmet a coherent metallic THz response emerges. This metal-to-insulator-type, orbital-selective transition is indicated by an isosbestic point in the temperature dependence of the optical conductivity and dielectric constant at THz frequencies. At Tgap=61 K, a gap opens in the THz regime and then the superconducting transition occurs at Tc=32 K. This sequence of temperatures seems to reflect a corresponding hierarchy of the electronic correlations in different bands.

This study was performed using TeraView's TPS Spectra 3000 system. (TeraView, Cambridge, UK)

Full Article: http://www.nature.com/ncomms/2014/140128/ncomms4202/abs/ncomms4202.html