optical measurements
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2022 ◽  
Author(s):  
Adawiya Haider ◽  
Ghalib Ali ◽  
Mohammed Haider ◽  
Amer Dheyab ◽  
Amin Thamir

Abstract Pulsed Laser Deposition (PLD) technique was performed to deposit the pure Titanium oxide (TiO2) nanoparticles on the glass substrate of temp. (100 - 400°C), using the doubled frequency of Nd: YAG laser wavelength of 532nm at (10) Hz rate, 10 nanosecond duration pulses and a constant laser energy 800 mJ. The optical measurements obtained by UV-Vis transmittance on deposited TiO2 films indicate the highest transparency in the visible wavelength region with an average transmittance of 80%. Estimated the relationship between the refractive index of TiO2 thin films with substrate temperature was n = 2.49 at 400 oC. Moreover, the calculated empirical relation between the energy gap and refractive index have similar to the work results.


2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Gianfranco Ulian ◽  
Giovanni Valdrè

AbstractCalcite (CaCO3, trigonal crystal system, space group $$R\overline{3}c$$ R 3 ¯ c ) is a ubiquitous carbonate phase commonly found on the Earth’s crust that finds many useful applications in both scientific (mineralogy, petrology, geology) and technological fields (optics, sensors, materials technology) because of its peculiar anisotropic physical properties. Among them, photoelasticity, i.e., the variation of the optical properties of the mineral (including birefringence) with the applied stress, could find usefulness in determining the stress state of a rock sample containing calcite by employing simple optical measurements. However, the photoelastic tensor is not easily available from experiments, and affected by high uncertainties. Here we present a theoretical Density Functional Theory approach to obtain both elastic and photoelastic properties of calcite, considering realistic experimental conditions (298 K, 1 atm). The results were compared with those available in literature, further extending the knowledge of the photoelasticity of calcite, and clarifying an experimental discrepancy in the sign of the p41 photoelastic tensor component measured in past investigations. The methods here described and applied to a well-known crystalline material can be used to obtain the photoelastic properties of other minerals and/or materials at desired pressure and temperature conditions.


2022 ◽  
Author(s):  
Clara Romero González-Quijano ◽  
Sonia Herrero Ortega ◽  
Peter Casper ◽  
Mark Gessner ◽  
Gabriel Singer

Abstract. Advances in analytical chemistry have facilitated the characterization of dissolved organic matter (DOM), which has improved understanding of DOM sources and transformations in surface waters. For urban waters, however, where DOM diversity is likely high, the interpretation of DOM signatures is hampered by a lack of basic information. Here we explored the spatiotemporal variation of DOM composition in contrasting urban water bodies, based on spectrophometry and fluorometry, size-exclusion chromatography and ultrahigh-resolution mass spectrometry, to identify linkages between DOM signatures and potential drivers. The highly diverse DOM we observed distinguished lakes and ponds characterized by a high proportion of autochthonous DOM from rivers and streams with more allochthonous DOM. Seasonal variation was apparent in all types of water bodies, driven by the interaction between phenology and urban influences. Specifically, nutrient supply, the percentage of green space adjacent to the water bodies and point source pollution emerged as major urban drivers of DOM composition. Optical DOM properties also revealed the influence of effluents from waste water treatment plants, suggesting their use in water-quality assessment and monitoring. Furthermore, optical measurements inform about processes both within water bodies and in their surroundings, which could improve the assessment of ecosystem functioning and integrity.


Author(s):  
Shokoofeh Abbaszadeh ◽  
Roberto Leidhold ◽  
Stefan Hoerner

AbstractFish mortality assessments for turbine passages are currently performed by live-animal testing with up to a hundred thousand fish per year in Germany. A propelled sensor device could act as a fish surrogate. In this context, the study presented here investigates the state of the art via a thorough literature review on propulsion systems for aquatic robots. An evaluation of propulsion performance, weight, size and complexity of the motion achievable allows for the selection of an optimal concept for such a fish mimicking device carrying the sensors. In the second step, the design of a bioinspired soft robotic fish driven by an unconventional drive system is described. It is based on piezoceramic actuators, which allow for motion with five degrees of freedom (DOF) and the creation of complex bio-mimicking body motions. A kinematic model for the motion’s characteristics is developed, to achieve accurate position feedback with the use of strain gauges. Optical measurements validate the complex deformation of the body and deliver the basis for the calibration of the kinematic model. Finally, it can be shown, that the calibrated model presented allows the tracking of the deformation of the entire body with an accuracy of 0.1 mm.


Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Qifa Wang ◽  
Chenyang Li ◽  
Liping Hou ◽  
Hanmou Zhang ◽  
Xuetao Gan ◽  
...  

Abstract Plasmonic radial breathing mode (RBM), featured with radially oscillating charge density, arises from the surface plasmon waves confined in the flat nanoparticles. The zero net dipole moment endows the RBM with an extremely low radiation yet a remarkable intense local field. On the other hand, owing to the dark mode nature, the RBMs routinely escape from the optical measurements, severely preventing their applications in optoelectronics and nanophotonics. Here, we experimentally demonstrate the existence of RBM in a hexagonal Au nanoplate-on-mirror nanocavity using a far-field linear-polarized light source. The polarization-resolved scattering measurements cooperated with the full-wave simulations elucidate that the RBM originates from the standing plasmon waves residing in the Au nanoplate. Further numerical analysis shows the RBM possesses the remarkable capability of local field enhancement over the other dark modes in the same nanocavity. Moreover, the RBM is sensitive to the gap and nanoplate size of the nanocavity, providing a straightforward way to tailor the wavelength of RBM from the visible to near-infrared region. Our approach provides a facile optical path to access to the plasmonic RBMs and may open up a new route to explore the intriguing applications of RBM, including surface-enhanced Raman scattering, enhanced nonlinear effects, nanolasers, biological and chemical sensing.


2022 ◽  
Author(s):  
Stephen A. Whitmore ◽  
Cara I. Frischkorn ◽  
Spencer Peterson

2022 ◽  
Vol 93 (1) ◽  
pp. 013903
Author(s):  
Hyeokjun Heo ◽  
Taeho Kim ◽  
Yungi Jeong ◽  
Hangyeol Park ◽  
Joonho Jang

2022 ◽  
Vol 34 (2) ◽  
pp. 279-283
Author(s):  
J. Chandrasekar ◽  
Durgachalam Manikandan

In this work, chromium sulfide (CrS) thin films were grown on the acetic acid substrates by chemical bath deposition to prepare non-toxic photovoltaic devices. The combined single-source precursor approach has been developed for the deposition method using tris(diethyldithiocarbamato)chromium(III) for the deposition of CrS thin films grown at bath temperatures of 30, 60 and 90 ºC and at a constant deposition time of 30-120 min. The sufrace mophology of the prepared films have been analyzed by SEM and HR-TEM techniques. The study of the films indicate the distributed roughness and nano bundled hexagonal structures. The energy dispersive X-ray (EDX) spectroscopy analysis conformed the presence of Cr and S. The polycrystalline behaviour of the films was studied by an XRD study which revealed the mixed phases with a predicted crystallite size of 20 nm. The optical measurements showed films had a maximum transmittance of 90% in the visible region and the evaluated energy band varied in the range of 2.2-2.378 eV with the change of bath temperatures. This suggests that CrS thin film prepared at 90 ºC has enhanced crystalline superiority. According to photoluminescence (PL) analysis, the green emission can be attributed to the presence of several deep trap states or defects in the CrS structure. Moreover, natural dye sensitized solar cells (DSSCs) in CrS thin film prepared at 90 ºC, Jsc (28.0 mA/cm2) produced a larger voltage in the short circuit as compared to synthetic dye sensitized solar cells (DSSCs) using CrS thin film Jsc (22.5 mA/cm2).


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