scholarly journals Few-Cycle, μJ-Class, Deep-UV Source from Gas Media

2021 ◽  
Vol 11 (14) ◽  
pp. 6440
Author(s):  
Tsendsuren Khurelbaatar ◽  
Je-Hoi Mun ◽  
Jaeuk Heo ◽  
Yunman Lee ◽  
Dong-Eon Kim
Keyword(s):  
Frequency Conversion ◽  
Near Infrared ◽  
Laser Pulses ◽  
Weak Field ◽  
Uv Spectra ◽  
Generation Process ◽  
Experimental Conditions ◽  
Natural Time ◽  
Highly Nonlinear ◽  
Deep Uv

Energetic, few-fs pulses in the deep-UV region are highly desirable for exploring ultrafast processes on their natural time scales, especially in molecules. The deep-UV source can be generated from gas media irradiated with few-cycle near-infrared laser pulses via a third-order frequency conversion process, which is a perturbative mechanism in a relatively weak field regime. In this work, we demonstrate that the deep-UV generation process is significantly affected by also even higher nonlinear processes, such as the ionization depletion of gas and plasma-induced spatiotemporal distortion of propagating light. In the experiment, by optimizing the deep-UV (3.6–5.7 eV) generation efficiency, the highest deep-UV energy of 1 μJ was observed from a moderately ionized 0.8-bar Ar gas target. The observed UV spectra exhibited frequency shifts depending on the experimental conditions—gas type, gas pressure, and the gas cell location—supporting the importance of the highly nonlinear mechanisms. The experimental observations were well corroborated by numerical simulations.

scholarly journals Light Induces Opening of Vascular Barrier for Precise Nanoparticle Delivery

2020 ◽  
Author(s):  
Weizhi Qi ◽  
Tingting Li ◽  
Chen Zhang ◽  
Fei Liu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Near Infrared ◽  
Laser Pulses ◽  
Experimental Conditions ◽  
Nanoparticle Delivery ◽  
Therapeutic Drugs ◽  
Enhanced Permeability And Retention ◽  
Health And Disease ◽  
First Time ◽  
Nir Laser

The endothelial barrier plays an essential role in health and disease by protecting organs from toxins while allowing nutrients to access the circulation. However, it is the major obstacle that limits the delivery of therapeutic drugs to the diseased tissue. Here, for the first time we show that near-infrared (NIR) laser pulses can transiently open the vascular barrier via photoacoustic force, enabling selective and substantial accumulation of nanoparticles inside specific tissues. The nanoparticle delivery in tumors by 10-minute laser scanning is ~6 times higher than that of the enhanced permeability and retention (EPR) effect in 24 hours under current experimental conditions. We further show substantial accumulation of nanoparticles in the mouse brain with intact skull through light-controlled opening of the blood-brain barrier (BBB). This approach opens a new door for tissue-specific delivery of nanomaterials with an unprecedented level of efficiency and precision.

scholarly journals Light Induces Opening of Vascular Barrier for Precise Nanoparticle Delivery

2020 ◽  
Author(s):  
Weizhi Qi ◽  
Tingting Li ◽  
Chen Zhang ◽  
Fei Liu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Near Infrared ◽  
Laser Pulses ◽  
Experimental Conditions ◽  
Nanoparticle Delivery ◽  
Therapeutic Drugs ◽  
Enhanced Permeability And Retention ◽  
Health And Disease ◽  
First Time ◽  
Nir Laser

The endothelial barrier plays an essential role in health and disease by protecting organs from toxins while allowing nutrients to access the circulation. However, it is the major obstacle that limits the delivery of therapeutic drugs to the diseased tissue. Here, for the first time we show that near-infrared (NIR) laser pulses can transiently open the vascular barrier via photoacoustic force, enabling selective and substantial accumulation of nanoparticles inside specific tissues. The nanoparticle delivery in tumors by 10-minute laser scanning is ~6 times higher than that of the enhanced permeability and retention (EPR) effect in 24 hours under current experimental conditions. We further show substantial accumulation of nanoparticles in the mouse brain with intact skull through light-controlled opening of the blood-brain barrier (BBB). This approach opens a new door for tissue-specific delivery of nanomaterials with an unprecedented level of efficiency and precision.

Frequency conversion from near-infrared to mid-infrared in highly nonlinear optical fibres

2010 ◽  
Author(s):  
Nicolas Ducros ◽  
Franck Morin ◽  
Kevin Cook ◽  
Alexis Labruyère ◽  
Sébastien Février ◽  
...  
Keyword(s):  
Nonlinear Optical ◽  
Frequency Conversion ◽  
Near Infrared ◽  
Optical Fibres ◽  
Mid Infrared ◽  
Highly Nonlinear

scholarly journals Comprehensive modeling of bloodstain aging by multivariate Raman spectral resolution with kinetics

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Ayari Takamura ◽  
Daisuke Watanabe ◽  
Rintaro Shimada ◽  
Takeaki Ozawa
Keyword(s):  
Spectral Resolution ◽  
Aging Process ◽  
Near Infrared ◽  
Biochemical Characterization ◽  
Forensic Analysis ◽  
Chemical Mechanism ◽  
Experimental Conditions ◽  
Spectral Components ◽  
Different Temperatures ◽  
Analytical Approaches

Abstract Blood, as a cardinal biological system, is a challenging target for biochemical characterization because of sample complexity and a lack of analytical approaches. To reveal and evaluate aging process of blood compositions is an unexplored issue in forensic analysis, which is useful to elucidate the details of a crime. Here we demonstrate a spectral deconvolution model of near-infrared Raman spectra of bloodstain to comprehensively describe the aging process based on the chemical mechanism, particularly the kinetics. The bloodstain spectra monitored over several months at different temperatures are decomposed into significant spectral components by multivariate calculation. The kinetic schemes of the spectral components are explored and subsequently incorporated into the developed algorithm for the optimal spectral resolution. Consequently, the index of bloodstain aging is proposed, which can be used under different experimental conditions. This work provides a novel perspective on the chemical mechanisms in bloodstain aging and facilitates forensic applications.

scholarly journals Microstructure and Photothermal Conversion Performance of Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 Selective Absorbing Film for Non-Vacuum High-Temperature Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 124
Author(s):  
Haibin Geng ◽  
Hanzhe Ye ◽  
Xingliang Chen ◽  
Sibin Du
Keyword(s):  
Visible Light ◽  
Near Infrared ◽  
Substitutional Solid Solution ◽  
Experimental Conditions ◽  
Al Content ◽  
Spectrum Range ◽  
Light Interference ◽  
Transmission Electron ◽  
Conversion Performance ◽  
Columnar Grain

This paper aims to clarify the phase composition in each sub-layer of tandem absorber TiMoAlON film and verify its thermal stability. The deposited multilayer Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 films include an infrared reflectance layer, light interference absorptive layers with different metal doping amounts, and an anti-reflectance layer. The layer thicknesses of Ti, Mo-TiAlN, Mo-TiAlON, and Al2O3 are 100, 300, 200, and 80 nm, respectively. Al content increases to 12 at.% and the ratio of N/O is nearly 0.1, which means nitride continuously changes to oxide. According to X-ray Diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, the diffraction peak that appears at 2θ = 40° demonstrates that Mo element aggregates in the substitutional solid solution (Ti,Al)(O,N) columnar grain. TiMoAlON films have low reflectivity in the spectrum range of 300–900 nm. When Al content is more than 10 at.%, absorptivity is almost in the spectrum range from visible to infrared, but absorptivity decreases in the ultraviolet spectrum range. When Al content is increased to 12 at.%, absorptivity α decreases by 0.05 in the experimental conditions. After baking in atmosphere at 500 °C for 8 h, the film has the highest absorptivity when doped with 2 at.% Mo. In the visible-light range, α = 0.97, and in the whole ultraviolet-visible-light near-infrared spectrum range, α = 0.94, and emissivity ε = 0.02 at room temperature and ε = 0.10 at 500 °C.

scholarly journals Regulating disordered plasmonic nanoparticles into polarization sensitive metasurfaces

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shulei Li ◽  
Mingcheng Panmai ◽  
Shaolong Tie ◽  
Yi Xu ◽  
Jin Xiang ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Spatial Resolution ◽  
Metallic Nanoparticles ◽  
Near Infrared ◽  
Optical Memory ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Optical Diffraction ◽  
Plasmonic Nanoparticles ◽  
Direct Laser

Abstract Metasurfaces composed of regularly arranged and deliberately oriented metallic nanoparticles can be employed to manipulate the amplitude, phase and polarization of an incident electromagnetic wave. The metasurfaces operating in the visible to near infrared spectral range rely on the modern fabrication technologies which offer a spatial resolution beyond the optical diffraction limit. Although direct laser writing is an alternative to the fabrication of nanostructures, the achievement of regular nanostructures with deep-subwavelength periods by using this method remains a big challenge. Here, we proposed and demonstrated a novel strategy for regulating disordered plasmonic nanoparticles into nanogratings with deep-subwavelength periods and reshaped nanoparticles by using femtosecond laser pulses. The orientations of the nanogratings depend strongly on the polarization of the femtosecond laser light. Such nanogratings exhibit reflection and polarization control over the reflected light, enabling the realization of polarization sensitive optical memory and color display with high spatial resolution and good chromacity.

In situ monitoring of isophorone diisocyanate-based flexible polyurethane foams formation

2016 ◽  
Vol 54 (1) ◽  
pp. 37-52 ◽  
Author(s):  
I Eceiza ◽  
L Irusta ◽  
A Barrio ◽  
MJ Fernández-Berridi
Keyword(s):  
Foam Height ◽  
Polyurethane Foams ◽  
In Situ Monitoring ◽  
Generation Process ◽  
Isophorone Diisocyanate ◽  
Experimental Conditions ◽  
Foaming Process ◽  
Foam Generation ◽  
Flexible Polyurethane

Novel isophorone diisocyanate-based flexible polyurethane foams were prepared by the one-step method in a computerized foam qualification system (FOAMAT). The experimental conditions to obtain this type of foams, in relation to the nature and concentration of catalysts as well as the reaction temperature, were established as no data were available in scientific literature. The chemical reactions occurring during the foam generation process were monitored in situ by attenuated total reflectance-FTIR spectroscopy. The kinetics of the foam generation was fitted to an nth order model and the data showed that the foaming process adjusted to a first-order kinetics. The physical changes as pressure, foam height, and dielectric polarization were monitored by the FOAM software (FOAMAT). According to these parameters, the foaming process was divided into four steps: bubble growth, bubble packing, cell opening, and final curing.

Molecules in strong laser fields: vibrational inversion and harmonic generation

1994 ◽  
Vol 72 (3) ◽  
pp. 673-677 ◽  
Author(s):  
Eric E. Aubanel ◽  
André D. Bandrauk
Keyword(s):  
Harmonic Generation ◽  
Laser Pulses ◽  
Harmonic Spectrum ◽  
Femtosecond Laser Pulses ◽  
Generation Process ◽  
High Order Harmonic Generation ◽  
Vibrationally Excited ◽  
Potential Wells ◽  
High Order Harmonic ◽  
Vibrational Levels

We examine two consequences of the unique behaviour of molecules in strong fields. First, by time gating of laser-induced avoided crossings with femtosecond laser pulses, one can obtain efficient vibrational inversion into a narrow distribution of vibrational levels of a molecular ion. We demonstrate this by numerical solution of the time-dependent Schrödinger equation for [Formula: see text] Second, we show results of numerical calculation with vibrationally excited [Formula: see text] of harmonic generation up to the 11th order of an intense 1064- nm laser. We predict that competition of photodissociation can be minimized by trapping the molecule in high-field-induced potential wells, thus enhancing the high-order harmonic generation process. Furthermore, the harmonic spectrum can serve as a measure of the structure of these laser-induced potentials.

scholarly journals Nonperturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

2017 ◽  
Vol 5 ◽  
Author(s):  
Guihua Li ◽  
Hongqiang Xie ◽  
Ziting Li ◽  
Jinping Yao ◽  
Wei Chu ◽  
...  
Keyword(s):  
Excited State ◽  
Femtosecond Laser ◽  
Pulse Energy ◽  
Laser Pulses ◽  
Infrared Laser ◽  
Femtosecond Laser Pulses ◽  
Probe Laser ◽  
Laser Fields ◽  
Mid Infrared ◽  
Highly Nonlinear

We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the probe laser pulses indicate its nonperturbative characteristic.

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