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high harmonic generation

Xingguo Chen, Hongming Liu, Qi Wu, Xingxing Jiang, Xianggao Meng, Zheshuai Lin, Jingui Qin
A family of nonlinear optical materials that contain the halide, oxide and oxyhalide polar units simultaneously in a single structure, namely, ABi2(IO3)2F5 (A = K, 1;Rb,2 and Cs,3), have been designed and synthesized. They crystallize in the same polar space group of P21 with a two-dimensional double-layered framework constructed by [BiF5]2- and [BiO2F4]5- units connected to each other by four F atoms, in which two [IO3]- groups are linked to [BiO2F4]5- unit on the same side, and a hanging Bi-F bond of [BiF5]2- unit is located on the other side via ionic interaction with the layer-inserted alkali metal ions to form three-dimensional structure...
June 20, 2017: Angewandte Chemie
Suo Tang, Naveen Kumar, Christoph H Keitel
Plasma high-order-harmonic generation from an extremely intense short-pulse laser is explored by including the effects of ion motion, electron-ion collisions, and radiation reaction force in the plasma dynamics. The laser radiation pressure induces plasma ion motion through the hole-boring effect, resulting in frequency shifting and widening of the harmonic spectra. The classical radiation reaction force slightly mitigates the frequency broadening caused by the ion motion. Based on the results and physical considerations, parameter maps highlighting the optimum regions for generating a single intense attosecond pulse and coherent XUV radiation are presented...
May 2017: Physical Review. E
B Fetić, D B Milošević
Time evolution of the bound state of a molecular hydrogen cation in an intense, linearly polarized laser field is investigated by solving the full three-dimensional time-dependent Schrödinger equation. Our method is based on the Born-Oppenheimer and dipole approximations, and the wave function is expanded in finite series using B-spline functions and spherical harmonics in prolate spheroidal coordinates. After solving the stationary Schrödinger equation, the initial state is propagated under the influence of the laser field employing the Crank-Nicolson propagator...
May 2017: Physical Review. E
David R Carlson, Daniel D Hickstein, Alex Lind, Stefan Droste, Daron Westly, Nima Nader, Ian Coddington, Nathan R Newbury, Kartik Srinivasan, Scott A Diddams, Scott B Papp
We utilize silicon-nitride waveguides to self-reference a telecom-wavelength fiber frequency comb through supercontinuum generation, using 11.3 mW of optical power incident on the chip. This is approximately 10 times lower than conventional approaches using nonlinear fibers and is enabled by low-loss (<2  dB) input coupling and the high nonlinearity of silicon nitride, which can provide two octaves of spectral broadening with incident energies of only 110 pJ. Following supercontinuum generation, self-referencing is accomplished by mixing 780-nm dispersive-wave light with the frequency-doubled output of the fiber laser...
June 15, 2017: Optics Letters
Sandrine Donadio-Andréi, Karim Chikh, Christine Heuclin, Elisabetta Kuczewski, Anne Charrié, Anne-Sophie Gauchez, Catherine Ronin
OBJECTIVES: Measuring protein markers with variable glycosylation, such as thyroid-stimulating hormone (TSH), with high accuracy is not an easy task. Despite highly sensitive third-generation tests, discrepancies among TSH assays still remain unsolved and are the focus of important standardization efforts. Earlier work from our group showed that a lack of similarity in epitope expression between standards and samples may account for discordant hormone measurements. In this study, we aimed at producing a glycoengineered TSH with serum-type glycosylation and compared its immunological behavior to that of the international standards...
February 2017: European Thyroid Journal
Jinsheng Fang, Lijun Bao, Xu Li, Peter C M van Zijl, Zhong Chen
Background field removal is an important MR phase preprocessing step for quantitative susceptibility mapping (QSM). It separates the local field induced by tissue magnetic susceptibility sources from the background field generated by sources outside a region of interest, e.g. brain, such as air-tissue interface. In the vicinity of air-tissue boundary, e.g. skull and paranasal sinuses, where large susceptibility variations exist, present background field removal methods are usually insufficient and these regions often need to be excluded by brain mask erosion at the expense of losing information of local field and thus susceptibility measures in these regions...
May 10, 2017: Journal of Magnetic Resonance
E N Osika, A Chacón, M Lewenstein, B Szafran
An ambipolar n-p double quantum dot defined by potential variation along a semiconducting carbon-nanotube is considered. We focus on the (1e,1h) charge configuration with a single excess electron of the conduction band confined in the n-type dot and a single missing electron in the valence band state of the p-type dot for which lifting of the Pauli blockade of the current was observed in the electric-dipole spin resonance (Laird et al 2013 Nat. Nanotechnol. 8 565). The dynamics of the system driven by periodic electric field is studied with the Floquet theory and the time-dependent configuration interaction method with the single-electron spin-valley-orbitals determined for atomistic tight-binding Hamiltonian...
July 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Mayandi Sivaguru, Mohammad M Kabir, Manas Rangan Gartia, David S C Biggs, Barghav S Sivaguru, Vignesh A Sivaguru, Glenn A Fried, Gang Logan Liu, Sakthivel Sadayappan, Kimani C Toussaint
Second-harmonic generation (SHG) microscopy has gained popularity because of its ability to perform submicron, label-free imaging of noncentrosymmetric biological structures, such as fibrillar collagen in the extracellular matrix environment of various organs with high contrast and specificity. Because SHG is a two-photon coherent scattering process, it is difficult to define a point spread function (PSF) for this modality. Hence, compared to incoherent two-photon processes like two-photon fluorescence, it is challenging to apply the various PSF-engineering methods to improve the spatial resolution to be close to the diffraction limit...
June 8, 2017: Journal of Microscopy
Yevgeny Rakita, Omri Bar-Elli, Elena Meirzadeh, Hadar Kaslasi, Yagel Peleg, Gary Hodes, Igor Lubomirsky, Dan Oron, David Ehre, David Cahen
Halide perovskite (HaP) semiconductors are revolutionizing photovoltaic (PV) solar energy conversion by showing remarkable performance of solar cells made with HaPs, especially tetragonal methylammonium lead triiodide (MAPbI3). In particular, the low voltage loss of these cells implies a remarkably low recombination rate of photogenerated carriers. It was suggested that low recombination can be due to the spatial separation of electrons and holes, a possibility if MAPbI3 is a semiconducting ferroelectric, which, however, requires clear experimental evidence...
June 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
Iliya Tikhomirov, Takeshi Sato, Kenichi L Ishikawa
We theoretically study multielectron effects in high-harmonic generation (HHG), using all-electron first-principles simulations for a one-dimensional model atom. In addition to the usual plateau and cutoff (from a cation in the present case, since the neutral is immediately ionized), we find a prominent resonance peak far above the plateau and a second plateau extended beyond the first cutoff. These features originate from the dication response enhanced by orders of magnitude due to the action of the Coulomb force from the rescattering electron, and, hence, are a clear manifestation of electron correlation...
May 19, 2017: Physical Review Letters
Lasse Karvonen, Antti Säynätjoki, Mikko J Huttunen, Anton Autere, Babak Amirsolaimani, Shisheng Li, Robert A Norwood, Nasser Peyghambarian, Harri Lipsanen, Goki Eda, Khanh Kieu, Zhipei Sun
Grain boundaries have a major effect on the physical properties of two-dimensional layered materials. Therefore, it is important to develop simple, fast and sensitive characterization methods to visualize grain boundaries. Conventional Raman and photoluminescence methods have been used for detecting grain boundaries; however, these techniques are better suited for detection of grain boundaries with a large crystal axis rotation between neighbouring grains. Here we show rapid visualization of grain boundaries in chemical vapour deposited monolayer MoS2 samples with multiphoton microscopy...
June 5, 2017: Nature Communications
Liming Wu, Hua Lin, Hong Chen, Yu-Jun Zheng, Ju-Song Yu, Xin-Tao Wu
Mid-infrared (MIR, 2-20 μm) second-order nonlinear optical (NLO) materials with outstanding performances are great importance in laser science and technology. However, it is an enormous challenge to design and synthesize an excellent MIR NLO material lies in achieving simultaneously strong second harmonic generation (SHG) response [dij > 0.6  AgGaS2 (AGS)] and wide band gap (Eg > 3.5 eV). Here we report three new MIR NLO materials, AZn4Ga5S12 (A = K, Rb, Cs), which crystallize in the KCd4Ga5S12-type structure and adopt a 3D diamond-like framework (DLF) consisting of MS4 (M = Zn/Ga) tetrahedra, achieving the desired balance with strong powder SHG response (1...
June 3, 2017: Chemistry: a European Journal
Christopher A Arrell, José Ojeda, Luca Longetti, Alberto Crepaldi, Silvan Roth, Gianmarco Gatti, Andrew Clark, Frank van Mourik, Marcel Drabbels, Marco Grioni, Majed Chergui
Harmonium is a vacuum ultraviolet (VUV) photon source built within the Lausanne Centre for Ultrafast Science (LACUS). Utilising high harmonic generation, photons from 20-110 eV are available to conduct steady-state or ultrafast photoelectron and photoion spectroscopies (PES and PIS). A pulse preserving monochromator provides either high energy resolution (70 meV) or high temporal resolution (40 fs). Three endstations have been commissioned for: a) PES of liquids; b) angular resolved PES (ARPES) of solids and; c) coincidence PES and PIS of gas phase molecules or clusters...
May 31, 2017: Chimia
Ali Sarrami-Foroushani, Toni Lassila, Ali Gooya, Arjan J Geers, Alejandro F Frangi
Adverse wall shear stress (WSS) patterns are known to play a key role in the localisation, formation, and progression of intracranial aneurysms (IAs). Complex region-specific and time-varying aneurysmal WSS patterns depend both on vascular morphology as well as on variable systemic flow conditions. Computational fluid dynamics (CFD) has been proposed for characterising WSS patterns in IAs; however, CFD simulations often rely on deterministic boundary conditions that are not representative of the actual variations in blood flow...
December 8, 2016: Journal of Biomechanics
F Langer, M Hohenleutner, U Huttner, S W Koch, M Kira, R Huber
High-harmonic (HH) generation in crystalline solids1-6 marks an exciting development, with potential applications in high-efficiency attosecond sources7, all-optical bandstructure reconstruction8,9, and quasiparticle collisions10,11. Although the spectral1-4 and temporal shape5 of the HH intensity has been described microscopically1-6,12, the properties of the underlying HH carrier wave have remained elusive. Here we analyse the train of HH waveforms generated in a crystalline solid by consecutive half cycles of the same driving pulse...
April 2017: Nature Photonics
Karen Reiser, Patrick Stoller, André Knoesen
Collagen is a biological macromolecule capable of second harmonic generation, allowing label-free detection in tissues; in addition, molecular orientation can be determined from the polarization dependence of the second harmonic signal. Previously we reported that in-plane orientation of collagen fibrils could be determined by modulating the polarization angle of the laser during scanning. We have now extended this method so that out-of-plane orientation angles can be determined at the same time, allowing visualization of the 3-dimensional structure of collagenous tissues...
June 1, 2017: Scientific Reports
Jinyu Hu, Zuju Ma, Rongjian Sa, Yongfan Zhang, Kechen Wu
It is still a challenge to design and synthesize high performance broader ultraviolet non-linear optical (NLO) materials. Two new transition-metal silicates have recently attracted a lot of attention due to their strong phase-matched second harmonic generation (SHG) responses (about 4.5 times higher than KDP). However, the electronic and optical properties underlying the high performance of these materials and consequently, the possibility of designing more efficient silicates for NLO applications are not presently clear...
June 14, 2017: Physical Chemistry Chemical Physics: PCCP
Kerensa J Klottrup, Guillermo Miro-Quesada, Layla Flack, Ivan Pereda, Pamela Hawley-Nelson
The manufacturing process for biotherapeutics is closely regulated by the Food and Drug Administration (FDA), European Medicines Agency (EMA) and other regulatory agencies worldwide. To ensure consistency of the product of a manufacturing cell line, International Committee on Harmonization guidelines (Q5D, 1997) state that the cell substrate should be derived from a single cell progenitor, i.e., clonal.Cell lines in suspension culture may naturally revert to cell adhesion in the form of doublets, triplets and higher order structures of clustered cells...
May 27, 2017: Biotechnology Progress
R Mankowsky, A von Hoegen, M Först, A Cavalleri
We report on the demonstration of ultrafast optical reversal of the ferroelectric polarization in LiNbO_{3}. Rather than driving the ferroelectric mode directly, we couple to it indirectly by resonant excitation of an auxiliary high-frequency phonon mode with femtosecond midinfrared pulses. Because of strong anharmonic coupling between these modes, the atoms are directionally displaced along the ferroelectric mode and the polarization is transiently reversed, as revealed by time-resolved, phase-sensitive, second-harmonic generation...
May 12, 2017: Physical Review Letters
Kaiyue Li, Weiying Wang, Yanping Liu, Su Jiang, Guo Huang, Liming Ye
BACKGROUND: The active ingredients and thus pharmacological efficacy of traditional Chinese medicine (TCM) at different degrees of parching process vary greatly. OBJECTIVE: Near-infrared spectroscopy (NIR) was used to develop a new method for rapid online analysis of TCM parching process, using two kinds of chemical indicators (5-(hydroxymethyl) furfural [5-HMF] content and 420 nm absorbance) as reference values which were obviously observed and changed in most TCM parching process...
April 2017: Pharmacognosy Magazine
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