Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals. We show that this light-induced process is only partially reversible, and that the photogenerated aminoaldehyde and aminoaldehyde-pending groups undergo self-condensation to produce cross-linked, conjugated oligomers that absorb light in the visible spectrum up to the near-infrared range. Such a sequence of chemical reactions results in the formation of gel with two distinct morphologies: spheres and fiber-like matrices. To gain deeper insight into this process, we prepared poly(4-vinyl pyridine) with low molecular weight (about 2000 g/mol) and monitored the respective changes in absorption, fluorescence, 1H-NMR spectra, and electrical conductivity. The conductivity of the polymer gel upon irradiation changes from ionic to electronic, indicative of a conjugated molecular wire behavior. Quantum mechanical calculations confirmed the feasibility of the proposed polycondensation process. This new polyacetylene analog has potential in thermal energy-harvesting and sensor applications.

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STUDY OF MECHANISMS OF LIGHT ABSORPTION IN TITANIUM DIOXIDE FILMS

Тонкие химические технологии ◽

10.32362/2410-6593-2016-11-4-50-55 ◽

2016 ◽

Vol 11 (4) ◽

pp. 50-55

Author(s):

V. V. Novopashin ◽

L. A. Skvortsov ◽

M. I. Skvortsova

Keyword(s):

Titanium Dioxide ◽

Near Infrared ◽

Stoichiometric Composition ◽

Ionic Current ◽

Visible Spectrum ◽

Infrared Range ◽

Current Increase ◽

Titanium Dioxide Films ◽

532 Nm ◽

Near Infrared Range

This work is devoted to comparison of optical absorption value of titanium dioxide coatings obtained by means of reactive thermal evaporation (RTE) and its activated species (ARTE), as well as to study on the dependence of the absorption coefficient of the coatings on the process parameters. Special attention is paid to the study of the influence of the films nonstoichiometry on absorption in the visible and near-infrared ranges of the spectrum. The results allow concluding that the dominant mechanism responsible for absorption in titanium dioxide films in the near-infrared range of the spectrum is the deviation from the stoichiometric composition. This deviation is caused by the presence of defects in the coating structure such as oxygen vacancies (ions Ti3+), which are seen as electron traps. As oxygen pressure and ionic current increase, the absorption of titanium dioxide films is reduced, and films with a composition closer to stoichiometric are obtained. In turn, the absorption of titanium dioxide in the visible spectrum (at wavelengths of 532 nm and 670 nm) has less to do with defects in stoichiometry, in contrast to contaminating impurities contained in the starting material, in the vacuum chamber and in the jet gas.

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Increased sensitivity in a-SiC pinpin multilayers in the VIS-NIR range under UV light

MRS Proceedings ◽

10.1557/opl.2014.719 ◽

2014 ◽

Vol 1666 ◽

Author(s):

V. Silva ◽

I. Rodrigues ◽

M. A Vieira ◽

P. Louro ◽

M. Vieira

Keyword(s):

Steady State ◽

Near Infrared ◽

Uv Light ◽

Visible Spectrum ◽

Infrared Range ◽

Short Wavelength Range ◽

Infrared Wavelength ◽

Wavelength Division ◽

Near Ultraviolet ◽

Channel Separation

ABSTRACTIn this paper we experimentally demonstrate the use of near-ultraviolet steady state illumination to increase the spectral sensitivity of a double a-SiC/Si pi’n/pin photodiode beyond the visible spectrum (400 nm-880 nm). The concept is extended to implement a one by four wavelength division multiplexer with channel separation in the visible/near infrared range. Optoelectronic characterization of the device is presented and shows the feasibility of tailoring the wavelength and bandwidth of a polychromatic mixture. Several monochromatic pulsed lights in the VIS/NIR range, separately or in a polychromatic mixture illuminated the device. Independent tuning of the wavelengths is performed by steady state 390 nm optical bias superimposed from front and back sides. Results show that, front background enhances the light-to-dark sensitivity of the medium, long and infrared wavelength channels, and quench strongly the shorter wavelengths. Back background has the opposite effect; it only enhances the channel magnitude in short wavelength range and strongly reduces it in the long ones. This nonlinearity provides the possibility for selective tuning a specific wavelength. A capacitive optoelectronic model supports the experimental results. A numerical simulation is presented.

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Infrared and Visible—Near Infrared Electroluminescence Developments for FA in AlGaN/GaN HEMTS on SiC

ISTFA 2010: Conference Proceedings from the 36th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2010p0393 ◽

2010 ◽

Author(s):

M. Bouya ◽

D. Carisetti ◽

J.C. Clement ◽

N. Malbert ◽

N. Labat ◽

...

Keyword(s):

Failure Analysis ◽

Near Infrared ◽

High Electron Mobility Transistor ◽

Low Noise ◽

Civil Defense ◽

Base Stations ◽

Infrared Range ◽

High Electron ◽

Radar Applications ◽

Gan Hemts

Abstract HEMT (High Electron Mobility Transistor) are playing a key role for power and RF low noise applications. They are crucial components for the development of base stations in the telecommunications networks and for civil, defense and space radar applications. As well as the improvement of the MMIC performances, the localization of the defects and the failure analysis of these devices are very challenging. To face these challenges, we have developed a complete approach, without degrading the component, based on front side failure analysis by standard (Visible-NIR) and Infrared (range of wavelength: 3-5 µm) electroluminescence techniques. Its complementarities and efficiency have been demonstrated through two case studies.

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An Infrared Microscope for Use on a Focused Ion Beam for Circuit Edit and Backside Edit Applications

ISTFA 2015: Conference Proceedings from the 41st International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2015p0097 ◽

2015 ◽

Author(s):

Alexander Richards ◽

Matthew Weschler ◽

Michael Durller

Keyword(s):

Focused Ion Beam ◽

Near Infrared ◽

Ion Beam ◽

Visible Spectrum ◽

Camera System ◽

Buried Structures ◽

Ir Camera ◽

Area Of Interest ◽

Near Ultraviolet ◽

Infrared Microscope

Abstract To help solve the navigational problem, i.e., being able to successfully locate a circuit for probing or editing without destroying chip functionality, a near-infrared (NIR), near-ultraviolet (NUV), and visible spectrum camera system was developed that attaches to most focused ion beam (FIB) or scanning electron microscope vacuum chambers. This paper reviews the details of the design and implementation of the NIR/NUV camera system, as instantiated upon the FEI FIB 200, with a particular focus on its use for the visualization of buried structures, and also for non-destructive real time area of interest location and end point detection. It specifically considers the use of the micro-optical camera system for its benefit in assisting with frontside and backside circuit edit, as well as other typical FIB milling activities. The quality of the image obtained by the IR camera rivals or exceeds traditional optical based imaging microscopy techniques.

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Creation of Negatively Charged Boron Vacancies in Hexagonal Boron Nitride Crystal by Electron Irradiation and Mechanism of Inhomogeneous Broadening of Boron Vacancy-Related Spin Resonance Lines

Nanomaterials ◽

10.3390/nano11061373 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1373

Author(s):

Fadis F. Murzakhanov ◽

Boris V. Yavkin ◽

Georgiy V. Mamin ◽

Sergei B. Orlinskii ◽

Ivan E. Mumdzhi ◽

...

Keyword(s):

Boron Nitride ◽

Electron Irradiation ◽

Near Infrared ◽

Hexagonal Boron Nitride ◽

Optical Excitation ◽

High Energy ◽

Infrared Range ◽

Zero Field ◽

Zero Field Splitting ◽

Spin Resonance

Optically addressable high-spin states (S ≥ 1) of defects in semiconductors are the basis for the development of solid-state quantum technologies. Recently, one such defect has been found in hexagonal boron nitride (hBN) and identified as a negatively charged boron vacancy (VB−). To explore and utilize the properties of this defect, one needs to design a robust way for its creation in an hBN crystal. We investigate the possibility of creating VB− centers in an hBN single crystal by means of irradiation with a high-energy (E = 2 MeV) electron flux. Optical excitation of the irradiated sample induces fluorescence in the near-infrared range together with the electron spin resonance (ESR) spectrum of the triplet centers with a zero-field splitting value of D = 3.6 GHz, manifesting an optically induced population inversion of the ground state spin sublevels. These observations are the signatures of the VB− centers and demonstrate that electron irradiation can be reliably used to create these centers in hBN. Exploration of the VB− spin resonance line shape allowed us to establish the source of the line broadening, which occurs due to the slight deviation in orientation of the two-dimensional B-N atomic plains being exactly parallel relative to each other. The results of the analysis of the broadening mechanism can be used for the crystalline quality control of the 2D materials, using the VB− spin embedded in the hBN as a probe.

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AlInGaAs Multiple Quantum Well-Integrated Device with Multifunction Light Emission/Detection and Electro-Optic Modulation in the Near-Infrared Range

ACS Omega ◽

10.1021/acsomega.1c00668 ◽

2021 ◽

Vol 6 (12) ◽

pp. 8687-8692

Author(s):

Xin Li ◽

Shuyu Ni ◽

Yan Jiang ◽

Jie Li ◽

Wei Wang ◽

...

Keyword(s):

Quantum Well ◽

Near Infrared ◽

Light Emission ◽

Multiple Quantum Well ◽

Infrared Range ◽

Multiple Quantum ◽

Electro Optic ◽

Emission Detection ◽

Integrated Device ◽

Near Infrared Range

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Assessment of chicken breast shelf life based on bench-top and portable NIR spectroscopy tools coupled with chemometrics

Food Quality and Safety ◽

10.1093/fqsafe/fyaa032 ◽

2020 ◽

Author(s):

Ilaria Lanza ◽

Daniele Conficoni ◽

Stefania Balzan ◽

Marco Cullere ◽

Luca Fasolato ◽

...

Keyword(s):

Discriminant Analysis ◽

Shelf Life ◽

Meat Quality ◽

Near Infrared ◽

Nir Spectroscopy ◽

Life Assessment ◽

Chicken Breast ◽

Portable Devices ◽

Physicochemical Processes ◽

Insight Into

Abstract Near-infrared (NIR) spectroscopy is a rapid technique able to assess meat quality even if its capability to determine the shelf life of chicken fresh cuts is still debated, especially for portable devices. The aim of the study was to compare bench-top and portable NIR instruments in discriminating between four chicken breast refrigeration times (RT), coupled with multivariate classifier models. Ninety-six samples were analysed by both NIR tools at 2, 6, 10 and 14 days post-mortem. NIR data were subsequently submitted to partial least squares discriminant analysis (PLS-DA) and canonical discriminant analysis (CDA). The latter was preceded by double feature selection based on Boruta and Stepwise procedures. PLS-DA sorted moderate separation of RT theses, while shelf life assessment was more accurate on application of Stepwise-CDA. Bench-top tool had better performance than portable one, probably because it captured more informative spectral data as shown by the variable importance in projection (VIP) and restricted pool of Stepwise-CDA predictive scores (SPS). NIR tools coupled with a multivariate model provide deep insight into the physicochemical processes occurring during storage. Spectroscopy showed reliable effectiveness to recognise a 7-day shelf life threshold of breasts, suitable for routine at-line application for screening of meat quality.

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High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

Applied Sciences ◽

10.3390/app11156992 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6992

Author(s):

Tie Zhang ◽

Yuxin Xing ◽

Gaoxuan Wang ◽

Sailing He

Keyword(s):

Photoacoustic Spectroscopy ◽

Continuous Monitoring ◽

Near Infrared ◽

Resonant Cavity ◽

High Sensitivity ◽

Industrial Applications ◽

Detection Sensitivity ◽

Infrared Range ◽

Wavelength Modulation ◽

Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

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Spectroscopic detection of forest diseases: a review (1970–2020)

Journal of Forestry Research ◽

10.1007/s11676-021-01378-w ◽

2021 ◽

Author(s):

Lorenzo Cotrozzi

Keyword(s):

Early Detection ◽

Optical Sensors ◽

Near Infrared ◽

Sustainable Forest Management ◽

Visible Spectrum ◽

Cost Effective ◽

Infrared Region ◽

Forest Disturbances ◽

Effective Manner ◽

Forest Diseases

AbstractSustainable forest management is essential to confront the detrimental impacts of diseases on forest ecosystems. This review highlights the potential of vegetation spectroscopy in improving the feasibility of assessing forest disturbances induced by diseases in a timely and cost-effective manner. The basic concepts of vegetation spectroscopy and its application in phytopathology are first outlined then the literature on the topic is discussed. Using several optical sensors from leaf to landscape-level, a number of forest diseases characterized by variable pathogenic processes have been detected, identified and quantified in many country sites worldwide. Overall, these reviewed studies have pointed out the green and red regions of the visible spectrum, the red-edge and the early near-infrared as the spectral regions most sensitive to the disease development as they are mostly related to chlorophyll changes and symptom development. Late disease conditions particularly affect the shortwave-infrared region, mostly related to water content. This review also highlights some major issues to be addressed such as the need to explore other major forest diseases and geographic areas, to further develop hyperspectral sensors for early detection and discrimination of forest disturbances, to improve devices for remote sensing, to implement long-term monitoring, and to advance algorithms for exploitation of spectral data. Achieving of these goals will enhance the capability of vegetation spectroscopy in early detection of forest stress and in managing forest diseases.

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