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Ritwik Mondal, Marco Berritta, Peter Oppeneer
Femtosecond magneto-optical pump-probe measurements of ultrafast demagnetization show an intriguing difference in the first 100 fs of the magneto-optical Kerr response depending on whether the polarization of the pump and probe beams are in parallel or perpendicular configuration [Bigot {\it et al.}, Nature Phys. {\bf 5}, 515 (2009)]. Starting from a most general relativistic Hamiltonian we focus on the ultra-relativistic light-spin interaction and show that this coupling term leads to different light-induced opto-magnetic fields when pump and probe polarization are parallel and perpendicular to each other, providing thus an explanation for the measurements...
March 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Antonella Gentile, Francesco Ruffino, Maria Grazia Grimaldi
Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure...
June 6, 2016: Nanomaterials
Carlo Massaroni, Elena Carraro, Andrea Vianello, Sandra Miccinilli, Michelangelo Morrone, Irisz K Levai, Emiliano Schena, Paola Saccomandi, Silvia Sterzi, John W Dickinson, Samantha Winter, Sergio Silvestri
BACKGROUND: Optoelectronic plethysmography (OEP) is a non-invasive motion capture method to measure chest wall movements and estimate lung volumes. OBJECTIVES: To provide an overview of the clinical findings and research applications of OEP in the assessment of breathing mechanics across populations of healthy and diseased individuals. METHODS: A bibliographic research was performed with the terms "opto-electronic plethysmography," "optoelectronic plethysmography," and "optoelectronic plethysmograph" in 50 digital library and bibliographic search databases resulting in the selection of 170 studies...
March 23, 2017: Respiration; International Review of Thoracic Diseases
Antony C S Chan, Ho-Cheung Ng, Sharat C V Bogaraju, Hayden K H So, Edmund Y Lam, Kevin K Tsia
Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate - hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process...
March 17, 2017: Scientific Reports
Man-Nung Su, Pratiksha Dongare, Debadi Chakraborty, Yue Zhang, Chongyue Yi, Fangfang Wen, Wei-Shun Chang, Peter Nordlander, John Elie Sader, Naomi J Halas, Stephan Link
Aluminum nanostructures support tunable surface plasmon resonances and have become an alternative to gold nanoparticles. While gold is the most-studied plasmonic material, aluminum has the advantage of high earth abundance and hence low cost. In addition to understanding the size and shape tunability of the plasmon resonance, the fundamental relaxation processes in aluminum nanostructures after photo-excitation must be understood, to take full advantage of applications such as photocatalysis and photodetection...
March 16, 2017: Nano Letters
Ching-Hwa Ho, Ya-Han Chen, Yung-Kang Kuo, C W Liu
The semiconductor optoelectronic properties of an inorganic (Bi(Bi2S3)9I3)2/3 hexagonal nano-/micro-rod are firstly explored herein. Transmittance and thermoreflectance measurements show that (Bi(Bi2S3)9I3)2/3 hexagonal rods possess an indirect gap of 0.73 eV and a direct gap of 1.08 eV, respectively. Hot-probe measurements of (Bi(Bi2S3)9I3)2/3 reveal the p-type semiconductor behavior and high thermoelectric voltage. Polarized Raman measurements of the m-plane (Bi(Bi2S3)9I3)2/3 (along c and perpendicular to the c axis) identify the structural anisotropy of the hexagonal nano-/micro-rod...
March 16, 2017: Chemical Communications: Chem Comm
Wahib Aggoune, Caterina Cocchi, Dmitrii Nabok, Karim Rezouali, Mohamed Akli Belkhir, Claudia Draxl
By investigating the optoelectronic properties of prototypical graphene/hexagonal boron nitride (h-BN) heterostructures, we demonstrate how a nanostructured combination of these materials can lead to a dramatic enhancement of light-matter interaction and give rise to unique excitations. In the framework of ab initio many-body perturbation theory, we show that such heterostructures absorb light over a broad frequency range, from the near-infrared to the ultraviolet (UV), and that each spectral region is characterized by a specific type of excitations...
March 20, 2017: Journal of Physical Chemistry Letters
Jinhua Hong, Chuanhong Jin, Jun Yuan, Ze Zhang
Two-dimensional layered graphene-like crystals including transition-metal dichalcogenides (TMDs) have received extensive research interest due to their diverse electronic, valleytronic, and chemical properties, with the corresponding optoelectronics and catalysis application being actively explored. However, the recent surge in two-dimensional materials science is accompanied by equally great challenges, such as defect engineering in large-scale sample synthesis. It is necessary to elucidate the effect of structural defects on the electronic properties in order to develop an application-specific strategy for defect engineering...
March 10, 2017: Advanced Materials
Zhenzhen Qin, Guangzhao Qin, Xu Zuo, Zhihua Xiong, Ming Hu
Two-dimensional (2D) materials with graphene as a representative have been intensively studied for a long time. Recently, monolayer gallium nitride (ML GaN) with honeycomb structure was successfully fabricated in experiments, generating enormous research interest for its promising applications in nano- and opto-electronics. Considering all these applications are inevitably involved with thermal transport, systematic investigation of the phonon transport properties of 2D GaN is in demand. In this paper, by solving the Boltzmann transport equation (BTE) based on first-principles calculations, we performed a comprehensive study of the phonon transport properties of ML GaN, with detailed comparison to bulk GaN, 2D graphene, silicene and ML BN with similar honeycomb structure...
March 15, 2017: Nanoscale
Farzaneh Shayeganfar, Javad Beheshtiyan, Mehdi Neek-Amal, Rouzbeh Shahsavari
Inspired by recent experiments, the trapping of molecules in 2D materials has gained increasing attention due to the unique ability of the molecules to modulate the electronic and optical properties of 2D materials, which calls for fundamental understanding and predictive design strategies. Herein, we focus on mono- and double-layer graphene encapsulating various MgO clusters and explore their diverse electronic and optical properties using a number of high-level first-principles calculations. By correlating the stability of adsorption, geometry, charge transfer, band structures, optical absorption spectrum, and the van der Waals pressure, our results decode various synergies in electro- and opto-mutable properties of MgO/graphene systems...
March 14, 2017: Nanoscale
Gobind Basnet, Krishna R Panta, Prem S Thapa, Bret N Flanders
This paper describes the electrochemical growth of branchless gold nanoribbons with ∼40 nm × ∼300 nm cross sections and >100 μm lengths (giving length-to-thickness aspect ratios of >10(3)). These structures are useful for opto-electronic studies and as nanoscale electrodes. The 0.75-1.0 V voltage amplitude range is optimal for branchless ribbon growth. Reduced amplitudes induce no growth, possibly due to reversible redox chemistry of gold at reduced amplitudes, whereas elevated amplitudes, or excess electrical noise, induce significant side-branching...
February 13, 2017: Applied Physics Letters
Gyouil Jeong, Boogeon Choi, Deok-Soo Kim, Seongjin Ahn, Baekwon Park, Jin Hyoun Kang, Hongki Min, Byung Hee Hong, Zee Hwan Kim
Bilayer graphene (BLG) shows great potential as a new material for opto-electronic devices because its bandgap can be controlled by varying the stacking orders, as well as by applying an external electric field. An imaging technique that can visualize and characterize various stacking domains in BLG may greatly help in fully utilizing such properties of BLG. Here we demonstrate that infrared (IR) scattering-type scanning near-field optical microscopy (sSNOM) can visualize Bernal and non-Bernal stacking domains of BLG, based on the stacking-specific inter- and intra-band optical conductivities...
March 13, 2017: Nanoscale
Jessica A Alexander, Frank J Scheltens, Lawrence F Drummy, Michael F Durstock, Fredrik S Hage, Quentin M Ramasse, David W McComb
Advances in electron monochromator technology are providing opportunities for high energy resolution (10 - 200meV) electron energy-loss spectroscopy (EELS) to be performed in the scanning transmission electron microscope (STEM). The energy-loss near-edge structure in core-loss spectroscopy is often limited by core-hole lifetimes rather than the energy spread of the incident illumination. However, in the valence-loss region, the reduced width of the zero loss peak makes it possible to resolve clearly and unambiguously spectral features at very low energy-losses (<3eV)...
March 2, 2017: Ultramicroscopy
Sana Sadeddine, Hanna Enriquez, Azzedine Bendounan, Pranab Kumar Das, Ivana Vobornik, Abdelkader Kara, Andrew J Mayne, Fausto Sirotti, Gérald Dujardin, Hamid Oughaddou
The remarkable properties of graphene stem from its two-dimensional (2D) structure, with a linear dispersion of the electronic states at the corners of the Brillouin zone (BZ) forming a Dirac cone. Since then, other 2D materials have been suggested based on boron, silicon, germanium, phosphorus, tin, and metal di-chalcogenides. Here, we present an experimental investigation of a single silicon layer on Au(111) using low energy electron diffraction (LEED), high resolution angle-resolved photoemission spectroscopy (HR-ARPES), and scanning tunneling microscopy (STM)...
March 10, 2017: Scientific Reports
Mustafa Ugur Daloglu, Aniruddha Ray, Zoltan Gorocs, Matthew Xiong, Ravinder Malik, Gal Bitan, Euan McLeod, Aydogan Ozcan
Significant progress in characterization of nanoparticles and biomolecules was enabled by the development of advanced imaging equipment with extreme spatial-resolution and sensitivity. To perform some of these analyses outside of well-resourced laboratories, it is necessary to create robust and cost-effective alternatives to existing high-end laboratory-bound imaging and sensing equipment. Towards this aim, we have designed a holographic on-chip microscope operating at an ultraviolet illumination wavelength (UV) of 266 nm...
March 9, 2017: Scientific Reports
Liang Wang, Jonathan A Cooper
The Reelin-Dab1 signaling pathway regulates development of the mammalian brain, including neuron migrations in various brain regions, as well as learning and memory in adults. Extracellular Reelin binds to cell surface receptors and activates phosphorylation of the intracellular Dab1 protein. Dab1 is required for most effects of Reelin, but Dab1-independent pathways may contribute. Here we developed a single-component, photoactivatable Dab1 (opto-Dab1) by using the blue light-sensitive dimerization/oligomerization property of A...
March 8, 2017: Scientific Reports
Narendra S Parmar, Haena Yim, Ji-Won Choi
Stable p-type conduction in ZnO has been a long time obstacle in utilizing its full potential such as in opto-electronic devices. We designed a unique experimental set-up in the laboratory for high Na-doping by thermal diffusion in the bulk ZnO single crystals. SIMS measurement shows that Na concentration increases by 3 orders of magnitude, to ~3 × 10(20) cm(-3) as doping temperature increases to 1200 °C. Electronic infrared absorption was measured for Na-acceptors. Absorption bands were observed near (0...
March 8, 2017: Scientific Reports
Takashi Tokuda, Satoki Noguchi, Satoru Iwasaki, Hiroaki Takehara, Toshihiko Noda, Kiyotaka Sasagawa, Jun Ohta
CMOS-based opto-electronic neural interface devices are presented. The devices are designed with target application of in vitro and in vivo optogenetics. Two types of the opto-electronic neural interface devices are presented. One is single-chip type device for on-chip optogenetics, and the other is multi-chip type device with flexibility and wide-area coverage for in vivo optogenetics on brain. Design, packaging and functional evaluations are presented.
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Chitraleema Chakraborty, Kenneth Matthew Goodfellow, Sajal Dhara, Anthony Yoshimura, Vincent Meunier, Nick Vamivakas
The optical properties of atomically thin semiconductor materials have been widely studied since the isolation of monolayer transition metal dichalcogenides (TMDCs). They have rich opto-electronic properties owing to their large direct bandgap, the interplay between the spin and the valley degree of freedom of charge carriers, and the recently discovered localized excitonic states giving rise to single photon emission. In this letter, we study the quantum-confined Stark effect of these localized emitters present near the edges of monolayer tungsten diselenide (WSe2)...
March 7, 2017: Nano Letters
Woomin Lee, Kenneth David Kihm, Hong Goo Kim, Seungha Shin, Changhyuk Lee, Jae Sung Park, Sosan Cheon, Oh Myoung Kwon, Gyumin Lim, Woorim Lee
Manipulation of the chemical vapor deposition graphene synthesis conditions, such as operating P, T, heating/cooling time intervals, and precursor gas concentration ratios (CH4/H2), allowed for synthesis of polycrystalline single-layered graphene with controlled grain sizes. The graphene samples were then suspended on 8 μm diameter patterned holes on a silicon-nitride (Si3N4) substrate, and the in-plane thermal conductivities k(T) for 320 K < T < 510 K were measured to be 2660-1230, 1890-1020, and 680-340 W/m·K for average grain sizes of 4...
March 6, 2017: Nano Letters
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