Single-mode waveguides for GRAVITY Perraut, K.; Jocou, L.; Berger, J. P. ...
Astronomy and astrophysics (Berlin),
06/2018, Volume:
614
Journal Article
Peer reviewed
Open access
Context.
Within the framework of the second-generation instrumentation of the Very Large Telescope Interferometer of the European Southern Observatory we have developed the four-telescope beam ...combiner in integrated optics.
Aims.
We optimized the performance of such beam combiners, for the first time in the near-infrared
K
band, for the GRAVITY instrument dedicated to the study of the close environment of the galactic centre black hole by precision narrow-angle astrometry and interferometric imaging.
Methods.
We optimized the design of the integrated optics chip and the manufacturing technology as well, to fulfil the very demanding throughput specification. We also designed an integrated optics assembly able to operate at 200 K in the GRAVITY cryostat to reduce thermal emission.
Results.
We manufactured about 50 beam combiners by silica-on-silicon etching technology. We glued the best combiners to single-mode fluoride fibre arrays that inject the VLTI light into the integrated optics beam combiners. The final integrated optics assemblies have been fully characterized in the laboratory and through on-site calibrations: their global throughput over the
K
band is higher than 55% and the instrumental contrast reaches more than 95% in polarized light, which is well within the GRAVITY specifications.
Conclusions.
While integrated optics technology is known to be mature enough to provide efficient and reliable beam combiners for astronomical interferometry in the
H
band, we managed to successfully extend it to the longest wavelengths of the
K
band and to manufacture the most complex integrated optics beam combiner in this specific spectral band.
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•Concentration dependent SERS studies.•Nucleophilic and electrophilic sites are identified.•Biological properties studies.•Molecular docking studies identifies the pharmacological ...property.
Spectroscopic analysis, density functional theory (DFT) studies and surface enhanced Raman scattering (SERS) of antimycobactetial 4-3-(4-acetylphenyl)ureido-2-hydroxybenzoic acid (AUHB) have been studied on different silver sols. For Raman and SERS wavenumbers, very large changes are observed. Observed variations in the modes of ring may be due to surface π-electron interactions and presence of this indicated that poly substituted ring is more inclined than para substituted phenyl ring and assumes a inclined position for concentration 10−3 M. Changes in orientation are seen in SERS spectra depending on concentration. In order to find electron-rich and poor sites of AUHB, molecular electrostatic potential was also constructed. The molecular docking results show that binding affinity and interactions with the receptor DprE1 may be supporting evidence for further studies in design further AUHB pharmaceutical applications. Based on antitubercular activity of 4-aminosalicylic acid (PAS) and urea derivatives we designed, synthesized and investigated mutual PAS-urea derivatives as potential antimycobacterial agents.
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•Sulfanilamide adsorption on pristine Ag3, Au3, Cu3 and AgAuCu clusters.•Short recovery time is suitable for drug desorption from nanoclusters.•Docking affinity in complexes is higher ...than that of SFM.
Using density functional theory (DFT) analysis, the adsorption characteristics of sulfanilamide (SFM) with Ag3/Au3/Cu3 and AgAuCu clusters are examined. To study the interaction of SFM with metal clusters, two different configurations are taken for SFM: X1 (near to NH2 at N5) and X2 (near to S = O2NH2). It is discovered that SFM forms stable clusters with metal clusters; in contrast to other clusters, complexation energy in SFM-X2 is highest for all complexes except for AgAuCu-SFMX1. The adsorption process, which is chemisorptions and results from charge transfer, has the ability to completely rearrange the potential of SFM-metal clusters. SFM-metal complexes exhibit a red shift in ultraviolet–visible (UV–Vis) absorption, with less intensity. The recovery time is extremely short and hence drug desorption from nanocluster proceeds quickly, making it appropriate for application of effective sensors.
•Concentration dependent SERS studies•Nucleophilic and electrophilic sites are identified•Docking studies reveals the pharmacological properties
Spectroscopic analysis, DFT studies and surface ...enhanced Raman scattering (SERS) of antimicrobial bioactive 4-(5-tert-butyl)2-hydroxybenzylideneamino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (THPB) have been studied on different silver sols. Intensity and hence enhancement variations are observed for Raman and SERS bands. Observed changes in the ring modes may be due to surface π-electron interactions and presence of this indicated that molecule is inclined with respect to the metal surface. Changes in orientation are seen in SERS spectra depending on concentration. The molecular docking results show that binding affinity and interactions with the receptors may be supporting evidence for further studies in design further THPB pharmaceutical applications. Reactivity properties are obtained from DFT analysis.
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•Concentration dependant SERS studies.•Nucleophilic and electrophilic sites are identified.•Biological properties studies.•Molecular docking studies identifies the pharmacological property.
...Spectroscopic analysis, DFT studies and surface enhanced Raman scattering of antimicrobial bioactive 4-(2‑hydroxy-3,5-diiodobenzylidene)amino-N-(5-methylisoxazole-3-yl)benzenesulfonamide (HDMB) have been studied. Changes in intensity and enhancement variations are observed for Raman and SERS bands. Changes observed in the ring mode vibrations may be due to surface π-electron interactions which means molecule is orientated in a tilted position with respect to metal surface. Changes in orientation are seen in SERS spectra depending on concentration. The molecular docking results show that binding affinity and interactions with the receptors may be supporting evidence for further studies in design further HDMB pharmaceutical applications. Reactivity properties are obtained from DFT analysis.
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•SERS spectra of an acetamido derivative in silver colloids.•Energy gap is dramaticall lowered after adsorption with silver cluster.•Orientation changes with concentration changes as evident from the ...presence of various raman modes in the SERS spectrum.
Based on Density Functional Theory (DFT) calculations and the Surface Enhanced Raman Scattering (SERS) technique, the adsorption properties of p-tolyl 2-acetamido-3-(4-fluorophenyl)propanoate (AFP) on silver surface were examined. The title compound, AFP showed balanced inhibition of acetyl- and butyrylcholinesterase along with mild cytotoxicity of HepG2 cells according to the previous study. After adsorption on silver surface, the structural properties of AFP exhibit a small modification, indicating an interaction between the AFP and Ag6 cluster. Experimental research on AFP and SERS spectra at various concentrations was conducted. Raman frequencies for AFP and AFP adsorbed on silver were computed. FMOs for AFP and AFP adsorbed on the silver surface were conducted. After AFP was adsorbed on the silver, the energy gap was dramatically lowered. The greater bioactivity of AFP is caused by the lowering energy gap, which denotes the electron delocalization. According to SERS spectrum analysis, AFP was adsorbed on silver with a tilted orientation. As a result, the current study has been used as a model system to comprehend how silver nanoprticles (NP) interact with AFP. Silver nanoparticles are successfully used for the treatment of different diseases alone or in association with other active components and the incorporation of AFP with silver nanocolloids will act as a nanodrug delivery system.
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•Concentration dependent SERS studies.•Nucleophilic and electrophilic sites are identified.•Studied NLO properties, DSSC, MEP and NBO.•Molecular docking studies identifies the ...pharmacological property.
Spectroscopic analysis, density functional theory (DFT) studies and surface enhanced Raman scattering of 4-((3-bromo-5-chloro-2-hydroxybenzylidene)amino)benzoic acid (BCHB) have been studied on different silver colloids concentrations in order to know the particular chemical species responsible for the spectra. For Raman and surface enhanced Raman scattering (SERS) wavenumbers, changes are observed. Observed variations in the modes of ring may be due to interaction of the π-electrons and presence of this indicated that RingII is more inclined than RingI and the BCHB assumes inclined orientation for concentration 10-3 M. Changes in orientation are seen in SERS spectra depending on concentration. In order to determine the electron-rich and poor sites of BCHB, the molecular electrostatic potential was also constructed. The molecular docking studies show that the bindings and interactions with the receptors may be supporting evidence for further studies in design further BCHB pharmaceutical applications.
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•SERS of TCB in silver colloids at various concentrations.•Redshift and decreased intensity of TCB-Ag6′s UV–vis spectra is due to adsorption in silver.•Polarizability increase of ...TCB-Ag6 is the cause of Raman enhancement.
In this work, the vibrational spectroscopy of the compound (E)-4-(tert-butyl)-Nˈ-(4-chlorobenzylidene)benzyhydrazide (TCB), which was studied in conjunction with theoretical calculations, is applied for Surface Enhanced Raman Scattering (SERS) studies. The assignments of the vibrational modes were completed with Density Functional Theory (DFT)/B3LYP/6-311++G*. The information gathered is utilized to determine the chemical and electrical characteristics in addition to wavenumber measurements. The TCB molecule’s chemisorbed status on colloidal nanoparticles is confirmed by acquired red shift and decreased intensity behavior in the UV–VIS spectrum analysis. Additionally, the SERS spectra at varied concentrations and the chemisorption of the molecule with metal cluster were recorded and examined. Additionally, a silver cluster-based theoretical SERS model is put forth. The findings presented here will help in the construction of more dependable SERS sensors by thoroughly describing the concentration-dependent profile of analyte orientation.
•Analysis of a carboxamide derivative's SERS spectra at different concentrations.•Theoretical modelling of SERS using silver cluster.•Presence of inactive Raman modes in SERS spectra with ...enhancements.
SERS at different concentrations and vibrational spectroscopic studies of N-butyl-2-isonicotinoylhydrazine-1-carboxamide (INC) are reported. DFT calculations based on silver cluster model and TD-DFT calculations support experimental observations. Raman band enhancements that are only present in some of the SERS spectra further point to the contribution of charge transfer interactions to the overall enhancements INC's Raman modes. The presence of the inactive nR bands in the SERS spectrum is due to the presence of Ag and these show the chemisorption nature of INC with the silver surface in an inclined orientation according to selection rules. The method created in this study can accurately quantify INC and might be applied to medications with structural relevance.
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•The adsorption behavior of folic acid on Cu3 clusters for different configurations.•SERS in the ABP-Cu3 clusters enhances the vibrational modes of ABP.•Appearance of new modes in the ...spectrum of complexes due to SERS.
The optical characteristics of folic acid (ABP) and metal clusters of copper (Cu3) at various locations were investigated by means of density functional theory (DFT) computations. Mulliken charge analysis and molecular electrostatic potential (MEP) surface show how charge moves from Cu3 to ABP through the various groups. The peak in the UV–Vis spectra of ABP-Cu3 is caused by bonding and anti-bonding orbitals. In both vacuum and aqueous conditions, the polarizability values of ABP-Cu3 cluster are significantly higher than those of pure ABP, indicating a possible enhancement of the nonlinear optical (NLO) effect. Our research investigates the possibility of using ABP adsorbed metal clusters for NLO materials. Surface enhanced Raman scattering (SERS) in the ABP adsorbed metal clusters enhances the vibrational modes of ABP. Adsorption energies are found to be in the range −17.08 to −58.52 kcal/mol in vacuum and −53.34 to −93.44 kcal/mol in aqueous medium for the different configurations for ABP-Cu3. It indicates that metal clusters adsorbed by ABP are stable in the aqueous media. Experimental IR and UV–Vis of ABP is in agreement with theoretically predicted ones.
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