Multiferroic transition-metal oxides: Analysis of the polar groundstates by dielectric spectroscopy

Source:		(2011) Auch gedruckt erschienen: ISBN 978-3-86664-977-4
pdf-format:		Dokument 1.pdf (5.469 KB) PhD Thesis, work carried out using TeraView's Spectra 3000

Transition-metal oxides show a broad spectrum of fascinating physical effects. Among these, materials with multiferroic properties play a prominent role in basic research and technical application.

The present work deals with several multiferroic compounds and the origins of their polar orders. LiCuVO4 and the rare-earth manganites RMnO3 show a polar order due to a complex magnetic structure. By measurements of polarisation in external magnetic fields, the relation between magnetic and polar order in LiCuVO4 is analysed. Dielectric spectroscopy reveals a relaxation process as key to the magnetocapacitive effects in the rare-earth manganites. Magnetite, which shows relaxorferroelectricity, is a system where the polar order is connected to the charge order of the system.

http://opus.bibliothek.uni-augsburg.de/volltexte/2011/1769/

in German

Institute:		Physics/ Materials Science
Faculty:		Faculty of Mathematics and Natural Sciences
Dewey Decimal Classification:		Physics
Document type:		Dissertation
Advisor:		Loidl, Alois (Prof. Dr.)
Language:		German
Date of examination:		17.05.2011
Year of creation:		2011
Date of publication:		22.07.2011

Maskless multiple-beam laser lithography for large-area nanostructure/microstructure fabrication

Min Tang, Zai Chun Chen, Zhi Qiang Huang, Yoo Sang Choo, andMing Hui Hong

Applied Optics, Vol. 50, Issue 35, pp. 6536-6542 (2011)
http://dx.doi.org/10.1364/AO.50.006536

Abstract

This paper reports a maskless multiple-beam laser lithography technique for large-area nanostructure/microstructure fabrication. This lithography technique can flexibly generate arbitrary nanostructures/microstructures over a large area at a high speed. The feature size of the nanostructures/microstructures can be controlled by exposure time and moving speed of the nanostage. Functional predesigned patterns, including split-ring resonator metamaterials for terahertz waves, can be obtained. More complicated structures can be made by single- and double-exposure schemes to make hybrid nanostructures/microstructures and tune surface plasmonic resonance properties. Meanwhile, microstructures with large height to lateral dimension ratios (2.5D microstructures) fabricated on silicon substrates can be used as mold tools for soft lithography. This technology shows its unique capacity to create various nanostructures/microstructures for extensive applications.

Measurements were performed using TeraView's TPS Spectra 3000 

... The line width of the SRR structure is ∼6μm, and the SRR dimension is 40μm. The trans-
mission spectra of the terahertz metamaterials are characterized by a terahertz time-domain
spectro- scope (TeraView, TPS3000) with a normal incident ...

Citation
Min Tang, Zai Chun Chen, Zhi Qiang Huang, Yoo Sang Choo, and Ming Hui Hong, "Maskless multiple-beam laser lithography for large-area nanostructure/microstructure fabrication," Appl. Opt. 50, 6536-6542 (2011)
http://www.opticsinfobase.org/abstract.cfm?URI=ao-50-35-6536

View Full Text: Acrobat PDF (747 KB)

STRUCTURAL APPLICATIONS OF TERAHERTZ SPECTROSCOPY

Journal of Molecular Structure

Volume 1006, Issues 1-3, 14 December 2011, Pages 66-76 STRUCTURAL APPLICATIONS OF TERAHERTZ SPECTROSCOPY

doi:10.1016/j.molstruc.2011.05.048 | How to Cite or Link Using DOI

  Permissions & Reprints

Terahertz spectroscopy: Its future role in medical diagnoses Edward Philip John Parrott a, Yiwen Sun a, 1, Emma Pickwell-MacPherson b, ,

Purchase

a     Electronic Engineering Department, The Chinese University of Hong Kong, New Territories, Hong Kong

b     Electronic & Computer Engineering, The Hong Kong University of Science & Technology, Clear Water Bay, Hong Kong

Available online 13 June 2011.

Abstract

Over the past two decades, terahertz radiation has received a lot of interest due to advances in emission and detection technologies in the late 1980s and early 1990s which allowed the construction of coherent source/detection regimes. This paper focuses on reviewing the use of terahertz radiation in the investigation and understanding of biological systems and medical diagnosis. In particular, research on terahertz spectroscopy of biomolecules, from amino acids to proteins is presented, and examples of potential medical applications are discussed.

Highlights

► Principles of terahertz spectroscopy. ► Properties of terahertz light. ► Time and frequency domain analysis of terahertz data. ► Molecular and medical terahertz spectroscopy.

Keywords: Terahertz imaging; Terahertz spectroscopy; Protein spectroscopy; Biomedical; Intermolecular interactions; Cancer

Article Outline

1. Introduction to terahertz radiation

1.1. Generation and detection of broadband pulses of terahertz radiation 1.2. Time-domain analysis 1.3. Frequency-domain analysis 1.4. Introduction to intermolecular interactions 2. Molecular spectroscopy 2.1. Introduction 2.2. Amino acids and peptides 2.3. Deoxyribonucleic acid (DNA) 2.4. Proteins 3. Medical spectroscopy 3.1. Understanding contrast 3.2. Enhancing contrast 3.3. Other medical applications 4. Summary Acknowledgments References

Corresponding author. Tel.: +852 2358 5034.

1Present address: Medical School, Shenzhen University, Guangdong, 518060, People’s Republic of China.

First Sale in Russia for TeraView

TeraView (http://www.teraview.com/), the pioneer and leader in Terahertz technology, along with its distributor in the region, Bruker Optics (www.bruker.com),  has just delivered and installed its first instrument in the Russian Federation at the Russian Academy of Sciences,  Institute of Cell biology (ICB RAS).
ICB was formed in 1990 under the prestigious umbrella of the Russian Academy of Sciences and performs studies in to the biophysics of cell function. The terahertz instrument will perform research intermolecular interactions and hydrogen bonding in cells structures in vitro.
The sale adds to TeraView’s growing installed base worldwide, and helps strengthen its position into an expanding research market in Russia.
Dr Don Arnone, TeraView’s CEO stated ‘Yet another sale of the TPS spectra 3000 adds to the growing list of prestigious academic institutes choosing our equipment and is an important first sale into the Russian academic market. We are hopeful it will lead to more users in the region”.

About Terahertz

Terahertz waves sit in the spectrum between Infrared and Microwave and as such have unique properties which enables them to pass through/into objects, and whilst so doing to transmit images and spectra which provide unique information in a safe, fast and non destructive manner.

Collective Mode Frequency Shifts in L-Serine and a Series of Isotopologues in the Terahertz Regime

by: David C. Hufnagle, Anita R. Taulbee-Combs, Wolfgang U. Spendel, Gilbert E. Pacey


Abstract

Terahertz (THz) time-domain spectroscopy was used to monitor collective mode shifts in L-serine, L-serine-2,3,3-d3, L-serine-d4, and L-serine-d7 at both room and liquid nitrogen (LN2) temperatures. Increasing the molecular mass by deuteration caused an expected absorbance red-shift; however, the magnitude of the displacement could not be predicted using normal mode analysis. Both modes at 67.8 cm−1 and 91.4 cm−1 demonstrated a greater peak shift upon deuterium substitution at non-hydrogen bonding sites than at sites that participated in hydrogen bonding. This is evident in the larger peak shifts observed in L-serine-d3 than in L-serine-d4, despite a smaller increase in mass. This leads to the conclusion that both peaks present in the room temperature spectra of L-serine likely arise primarily from other intermolecular interactions with <50% contribution from hydrogen bonding. This goes against the prediction that peaks in the THz spectra of amino acids are predominantly due to the hydrogen bonding network that makes up the crystal lattice.

View Abstract