A Comparison of the Near‐Infrared and Visible Spectra of Three Bright Cepheids

1997 ◽  
Vol 480 (2) ◽  
pp. 767-776 ◽  
Author(s):  
R. Paul Butler ◽  
Roger A. Bell
Keyword(s):  
Near Infrared ◽  
Visible Spectra

scholarly journals DEVELOPMENT OF ULTRA-SHORT HIGH INTENSITY LASERS FOR THE VISIBLE SPECTRA RANGE

2020 ◽  
Vol 17 (35) ◽  
pp. 739-752
Author(s):  
Hayder J. ABDULRAHMAN ◽  
Suzan B. MOHAMMED
Keyword(s):  
High Intensity ◽  
Laser Processing ◽  
Near Infrared ◽  
Laser Pulses ◽  
Dielectric Materials ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Visible Spectra ◽  
Short Laser Pulses ◽  
Micro Tools

Ultra-short laser pulses are particularly suitable for processing micro tools made of ultra-hard and dielectric materials. Ultra-short laser pulses provide a contact-free and precise fabrication of heat-sensitive materials such as visible spectra range. Visible spectra range has unique properties, which makes it an essential material in the tool, jewelry, and semiconductor industries. The processing of visible spectra range by ultra-short laser pulses is complex, as visible and near-infrared light is generally not absorbed. However, the intensity of ultra-short laser pulses is extremely high, so that the absorption scales nonlinearly with the intensity and, thus, visible or near-infrared light can be absorbed. The complexity also results from many partially interdependent process variables, such as the repetition rate, pulse overlap, track overlap, and scan speed. Excellent knowledge of the process is, therefore, essential for the production of micro tools. To make the laser processing accessible to a broader user field, the operator can be supported by a computer-aided design (CAD). The aim of this research was to the modeling of an ultra-short high-intensity laser for the visible spectra range in different environments of the angle of incidence, scanning speed, pulse, and track overlap. The experimental process included ultra-short pulsed laser processing of visible spectra range and surface analysis concerning modifications and ablation of the ultra-short laser. Ablation volumes were analyzed for single pulses, multi-pulses, and pockets. Pump-probe experiments reveal transient optical properties such as transmission or reflectivity. It was concluded that ultraviolet laser pulses are best suited to induce damage or modifications to visible spectra range surfaces. Additionally, shorter wavelengths have further advantages such as potentially longer Rayleigh lengths and smaller spot sizes.

scholarly journals A photochemical determination of luminescence efficiency of upconverting nanoparticles

2019 ◽  
Vol 15 ◽  
pp. 2671-2677 ◽  
Author(s):  
Baptiste Amouroux ◽  
Clément Roux ◽  
Jean-Claude Micheau ◽  
Fabienne Gauffre ◽  
Christophe Coudret
Keyword(s):  
Near Infrared ◽  
Green Emission ◽  
Accurate Estimation ◽  
Luminescent Probes ◽  
Luminescence Efficiency ◽  
Visible Spectra ◽  
Precise Quantification ◽  
Infrared Excitation

Upconverting nanoparticles are a rising class of non-linear luminescent probes burgeoning since the beginning of the 2000’s, especially for their attractiveness in theranostics. However, the precise quantification of the light delivered remains a hot problem in order to estimate their impact on the biological medium. Sophisticated photophysical measurements under near infrared excitation have been developed only by few teams. Here, we present the first attempt towards a simple and cheap photochemical approach consisting of an actinometric characterization of the green emission of NaYF4:Yb,Er nanoparticles. Using the recently calibrated actinometer 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)-3,3,4,4,5,5-hexafluoro-1-cyclopentene operating in the green region of the visible spectra, we propose a simple photochemical experiment to get an accurate estimation of the efficiency of these green-emitting “nanolamps”. The agreement of the collected data with the previous published results validates this approach.

scholarly journals Analysis of the visible spectra of some sperm-whale ferrimyoglobin derivatives

1968 ◽  
Vol 110 (2) ◽  
pp. 297-301 ◽  
Author(s):  
D. W. Smith ◽  
R. J. P. Williams
Keyword(s):  
Magnetic Susceptibility ◽  
High Spin ◽  
Linear Correlation ◽  
Near Infrared ◽  
Soret Band ◽  
Sperm Whale ◽  
Spin States ◽  
Infrared Band ◽  
Visible Spectra ◽  
The Relationship

The visible spectra of sperm-whale metmyoglobin and its fluoride, hydroxide, cyanide, azide, cyanate, formate, acetate, thiocyanate and nitrite derivatives were measured and resolved into Gaussian components. A linear correlation between the intensity of the band at 18500cm.−1 and the magnetic susceptibility is found, suggesting that the band is the β-band of the low-spin form. The analysed intensity of this band can be used to determine the relative proportions of the two spin states present. The spectra of the pure high-spin and low-spin components of each derivative can be reconstructed. Correlations between the energy of the near-infrared band and the visible bands of the high-spin form, and between the position and intensity of the 16000cm.−1 band, are demonstrated. The relationship between the position of the Soret band and the magnetic susceptibility can be explained in terms of the equilibrium between spin states.

Negative Index Metamaterials with Deeply Subwavelength Structural Dimensions from Near Infrared to Visible Based on Thin Filmsββ

2006 ◽  
Vol 964 ◽  
Author(s):  
Vitaliy Lomakin ◽  
Yeshaiahu Fainman ◽  
Gennady Shvets
Keyword(s):  
Near Infrared ◽  
Three Dimensional ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Index Of Refraction ◽  
Negative Permittivity ◽  
Electric Response ◽  
Visible Spectra ◽  
Infra Red ◽  
Unit Cells

ABSTRACTNovel two and three-dimensional doubly negative metamaterials (DNM), viz. metamaterial with simultaneously negative permittivity, permeability, and index of refraction, are introduced. The metamaterials comprise deeply subwavelength periodic unit cells, can be tuned to operate in the near infra-red and visible spectra, and can be manufactured using standard nanofabrication methods with compatible materials. The DNMs' unit cell comprises an optically thin metal film sandwiched between two thin metal strips or patches residing at a small distance from the film. The cavity formed between the strips or patches supports resonances with magnetic and electric response that can be tuned to exist in overlapping frequency bands thus leading to the DNM operation.

scholarly journals Spectral characterisation of 14 V-type candidate asteroids from the MOVIS catalogue

2020 ◽  
Vol 643 ◽  
pp. A107
Author(s):  
Pavol Matlovič ◽  
Julia de Leon ◽  
Hissa Medeiros ◽  
Marcel Popescu ◽  
Juan Luis Rizos ◽  
...  
Keyword(s):  
Near Infrared ◽  
Moving Objects ◽  
Main Belt ◽  
Spectral Parameters ◽  
James Bond ◽  
Basaltic Composition ◽  
The Family ◽  
Visible Spectra ◽  
Spectral Characterisation ◽  
Dynamical Family

Most of the currently known basaltic (V-type) asteroids are believed to be past or present members of the Vesta dynamical family. The rising discoveries of V-type asteroids that are not linked to the Vesta family dynamically suggest that a number of major basaltic bodies may have been present during the early stages of the solar system. Using the near-infrared (NIR) colour data in the Moving Objects from VISTA Survey (MOVIS) catalogue, a list of 477 V-type candidates was compiled, with more than half of them outside the Vesta family. In this work, we aim to provide a spectral analysis of 14 V-type candidates of various dynamical types. The computed visible and NIR spectral parameters are used to investigate evidence of space-weathering or mineralogical differences from the expected basaltic composition. Based on the analysis of their visible spectra, we confirm 11 new V-type asteroids: six low-i asteroids – (3188) Jekabsons, (3331) Kvistaberg, (4693) Drummond, (7223) Dolgorukij, (9007) James Bond, and (29733) 1999 BA4; along with four inner-other asteroids – (5524) Lecacheux, (19983) 1990 DW, (51742) 2001 KE55, and (90023) 2003 BD13; as well as one fugitive – (2275) Cuitlahuac. Additionally, we analysed three peculiar outer main belt V-type candidates based on their visible + NIR spectra. We confirm the diogenite-like composition of (2452) Lyot. The spectrum of asteroid (7302) is not consistent with a basaltic composition and likely reflects an S-type body. The spectrum of (14390) 1990 QP10 is similar to a V-type but it shows unique spectral features that suggest a peculiar composition. Overall, our results demonstrate the efficiency of the MOVIS catalogue in identifying V-type objects, with a success rate of over 85%. The identification of V-types in the inner main-belt is more likely due to the presence of the Vesta family and other nearby asteroids that had escaped from the family. In the middle and outer main belt, where the amount of data is more limited, the proportion of false positives increases.

Effect of Coupling Indium Tin Oxide with the TiO2–NaYF4:(Gd, Si) Composite for Photocatalytic Properties

2020 ◽  
Vol 20 (12) ◽  
pp. 7629-7635
Author(s):  
Shielah Mavengere ◽  
Sang-Chul Jung ◽  
Jung-Sik Kim
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Near Infrared ◽  
Visible Region ◽  
Impregnation Method ◽  
Solar Simulator ◽  
Visible Spectra ◽  
Multi Wavelength ◽  
Uv Visible ◽  
Ito Nanoparticles

Indium tin oxide (ITO) nanoparticles were coupled with NaYF4:(Gd, Si) using a TiO2-solution impregnation method. Scanning electron microscopy confirmed that TiO2 and ITO nanoparticles were loaded on the surface of the NaYF4:(Gd, Si) upconversion phosphor. The ultraviolet/visible spectra of the 20 wt.% ITO-NaYF4:(Gd, Si)/TiO2 composites were extended at the absorption edges towards the UV-visible region. The 20 wt.% ITO-coupled NaYF4:(Gd, Si)/TiO2 composites exhibited superior photocatalytic efficiency compared to only NaYF4:(Gd, Si)/TiO2 under near-infrared (NIR) irradiation. Multi-wavelength NIR photons of γ > 760 nm from a Xe solar simulator source induced photo-activation through the NaYF4:(Gd, Si) activator centers. The three-cycle photocatalytic reusability performance of the 20 wt.% ITO-impregnated NaYF4:(Gd, Si)/TiO2 composite was positively enhanced by up to 20% more than that of NaYF4:(Gd, Si)/TiO2.

scholarly journals Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes

2020 ◽  
Vol 495 (2) ◽  
pp. 2053-2062 ◽  
Author(s):  
J de León ◽  
J Licandro ◽  
C de la Fuente Marcos ◽  
R de la Fuente Marcos ◽  
L M Lara ◽  
...  
Keyword(s):  
Production Rate ◽  
Heliocentric Distance ◽  
Near Infrared ◽  
Visible Spectrum ◽  
Orbital Evolution ◽  
Gas Production ◽  
Infrared Observations ◽  
La Palma ◽  
Dust Size Distribution ◽  
Visible Spectra

ABSTRACT In this work, we present the results of an observational study of 2I/Borisov carried out with the 10.4-m Gran Telescopio Canarias (GTC) and the 3.6-m Telescopio Nazionale Galileo (TNG), both telescopes located at the Roque de Los Muchachos Observatory, in the island of La Palma (Spain). The study includes images in the visible and near-infrared, as well as visible spectra in the 3600–9200 Å wavelength range. N-body simulations were also performed to explore its orbital evolution and Galactic kinematic context. The comet’s dust continuum and near-infrared colours are compatible with those observed for Solar system comets. From its visible spectrum on the nights of 2019 September 24 and 26, we measured CN gas production rates Q(CN) = (2.3 ± 0.4) × 1024 mol s−1 and Q(CN) = (9.5 ± 0.2) × 1024 mol s−1, respectively, in agreement with measurements reported by other authors on similar nights. We also obtained an upper limit for the C2 production rate of Q(C2) < (4.5 ± 0.1) × 1024 mol s−1. Dust modelling results indicate a moderate dust production rate of ∼50 kg s−1 at heliocentric distance rh = 2.6 au, with a differential power-law dust size distribution of index ∼–3.4, within the range reported for many comet comae. Our simulations show that the Galactic velocity of 2I/Borisov matches well that of known stars in the solar neighbourhood and also those of more distant regions of the Galactic disc.

Principal Component Analysis of Near-Infrared and Visible Spectra: An Application to a XIIth Century Italian Work of Art

1995 ◽  
Vol 49 (4) ◽  
pp. 459-465 ◽  
Author(s):  
A. Orlando ◽  
M. Picollo ◽  
B. Radicati ◽  
S. Baronti ◽  
A. Casini
Keyword(s):  
Principal Component Analysis ◽  
Data Processing ◽  
Near Infrared ◽  
Statistical Data ◽  
Principal Component ◽  
Nondestructive Method ◽  
Colorimetric Analysis ◽  
Statistical Data Processing ◽  
Near Ir ◽  
Visible Spectra

Statistical data processing was performed on the spectra of a painting recorded in the near-infrared (near-IR) and visible (Vis) region by a totally nondestructive method. Results are discussed also in connection with colorimetric analysis.

scholarly journals Rational conversion of chromophore selectivity of cyanobacteriochromes to accept mammalian intrinsic biliverdin

2019 ◽  
Vol 116 (17) ◽  
pp. 8301-8309 ◽  
Author(s):  
Keiji Fushimi ◽  
Takatsugu Miyazaki ◽  
Yuto Kuwasaki ◽  
Takahiro Nakajima ◽  
Tatsuro Yamamoto ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Near Infrared ◽  
Covalent Bond ◽  
Long Wavelength ◽  
Mammalian Tissues ◽  
Visible Spectra ◽  
Mammalian Liver ◽  
Protein Pocket ◽  
Steric Hindrances

Because cyanobacteriochrome photoreceptors need only a single compact domain for chromophore incorporation and for absorption of visible spectra including the long-wavelength far-red region, these molecules have been paid much attention for application to bioimaging and optogenetics. Most cyanobacteriochromes, however, have a drawback to incorporate phycocyanobilin that is not available in the mammalian cells. In this study, we focused on biliverdin (BV) that is a mammalian intrinsic chromophore and absorbs the far-red region and revealed that replacement of only four residues was enough for conversion from BV-rejective cyanobacteriochromes into BV-acceptable molecules. We succeeded in determining the crystal structure of one of such engineered molecules, AnPixJg2_BV4, at 1.6 Å resolution. This structure identified unusual covalent bond linkage, which resulted in deep BV insertion into the protein pocket. The four mutated residues contributed to reducing steric hindrances derived from the deeper insertion. We introduced these residues into other domains, and one of them, NpF2164g5_BV4, produced bright near-infrared fluorescence from mammalian liver in vivo. Collectively, this study provides not only molecular basis to incorporate BV by the cyanobacteriochromes but also rational strategy to open the door for application of cyanobacteriochromes to visualization and regulation of deep mammalian tissues.

Enhanced photosensitivity of highly spectrum selective cylindrical gate In1−xGaxAs nanowire MOSFET photodetector

2019 ◽  
Vol 33 (12) ◽  
pp. 1950144
Author(s):  
Sanjeev Kumar Sharma ◽  
Balwinder Raj ◽  
Mamta Khosla
Keyword(s):  
Optical Sensors ◽  
High Performance ◽  
Near Infrared ◽  
Silicon Nanowire ◽  
Electrical Characterization ◽  
Oxide Semiconductor ◽  
Light Illumination ◽  
Interactive Display ◽  
Visible Spectra ◽  
Nanowire Mosfet

In this study, an [Formula: see text] nanowire metal oxide semiconductor field effect transistor (MOSFET) photosensor with zinc oxide (metallic ZnO), which act as a transparent optical window over channel has been investigated. The electrical characterization of [Formula: see text] nanowire MOSFET was compared to their silicon counterpart. [Formula: see text] nanowire MOSFET responds to visible-near infrared (600 nm to 1.7 nm) under light illumination as opposite to silicon nanowire MOSFET, which respond to ultraviolet to visible spectra (Peak @ 400 nm). ZnO–[Formula: see text]–InGaAs device is characterized by responsivity [Formula: see text] of [Formula: see text], photoconductive gain of [Formula: see text]%, with reasonable available photocurrent of [Formula: see text] and sensitivity [Formula: see text] of [Formula: see text]. The present work demonstrates the potential for high performance visible to near-infrared [Formula: see text] detectors with tunable band gaps for applications like interactive display, indoor communication and optical sensors.

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