scholarly journals Characterization and Evaluation of the Efficiency of TiO2/Zinc Phthalocyanine Nanocomposites as Photocatalysts for Wastewater Treatment Using Solar Irradiation

2008 ◽  
Vol 2008 ◽  
pp. 1-12 ◽  
Author(s):  
Antonio E. H. Machado ◽  
Marcela D. França ◽  
Valdemir Velani ◽  
Gabriel A. Magnino ◽  
Hosana M. M. Velani ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Visible Spectrum ◽  
Zinc Phthalocyanine ◽  
Solar Irradiation ◽  
Absorption Bands ◽  
Intense Absorption ◽  
Spectrum Region

This work reports the characterization of composites prepared by the association between zinc phthalocyanine (ZnPc) and titanium dioxide. These composites are better photocatalysts for wastewater decontamination mediated by solar radiation than pureTiO2, performance that remains even when reused. The UV-Vis diffuse reflectance absorption spectra show for these composites two intense absorption bands. The first covers the ultraviolet and part of the visible spectrum region until 460 nm (2.7 eV), whereas the second, nonstructured, goes from 475 nm until the near infrared with an absorption peak at 683 nm attributed to the Q band of ZnPc. The production of additionale−/h+pairs by these aggregates when photoexcited, their capability to act as charge carrier, the thickness and regularity of their distribution on theTiO2surface seem to be important parameters for the performance observed for these composites.

scholarly journals Assessing the Stability of Surface Lights for use in Retrievals of Nocturnal Atmospheric Parameters

2019 ◽  
Author(s):  
Jeremy E. Solbrig ◽  
Steven D. Miller ◽  
Jianglong Zhang ◽  
Lewis Grasso ◽  
Anton Kliewer
Keyword(s):  
Near Infrared ◽  
Correlation Coefficients ◽  
Visible Spectrum ◽  
Light Sources ◽  
Infrared Observations ◽  
Spatially Resolved ◽  
Relative Standard ◽  
Geometric Variables ◽  
The Stability

Abstract. Detection and characterization of aerosols is inherently limited at night due to a lack of sensitivity—information typically provided by visible spectrum observations. The VIIRS Day/Night Band (DNB) onboard the Suomi-NPP satellite is a first-of-its-kind calibrated sensor capable of collecting visible/near-infrared observations during both day and night. Multiple studies have suggested that anthropogenic light emissions such as those from cities and gas flares may be useable as light sources for retrieval of atmospheric properties including cloud and aerosol optical depth. However, their use in this capacity requires proper characterization of their intrinsic variation, which represents a source of retrieval uncertainty. In this study we use 18 months of cloud-cleared VIIRS data collected over five selected geographic domains to assess the stability of anthropogenic light emissions and their response to varied satellite and lunar geometries. Timeseries are developed for each location in each domain for DNB radiance, four infrared channels, and satellite and lunar geometric variables, and spatially-resolved correlation coefficients are computed between DNB radiance and each of the other variables. This analysis finds that while many emissive light sources are too unstable to be used reliably for atmospheric retrievals, some sources exhibit a sufficient stability (relative standard deviation

scholarly journals Detonation Nanodiamonds: A Comparison Study by Photoacoustic, Diffuse Reflectance, and Attenuated Total Reflection FTIR Spectroscopies

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2501
Author(s):  
Dmitry S. Volkov ◽  
Petr K. Krivoshein ◽  
Mikhail A. Proskurnin
Keyword(s):  
Diffuse Reflectance ◽  
Depth Profiling ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Comparison Study ◽  
Absorption Bands ◽  
Full Characterization ◽  
Ftir Spectrometry ◽  
Out Of Plane

The qualitative analysis of nanodiamonds by FTIR spectrometry as photoacoustic (FTIR–PAS), diffuse-reflectance (DRIFT), and attenuated total reflection (ATR) modalities was evaluated for rapid and nondestructive analysis and comparison of nanodiamonds. The reproducibility and signal-gathering depth of spectra was compared. The assignment of characteristic bands showed that only six groups of bands were present in spectra of all the modalities with appropriate sensitivity: 1760 (C=O stretch, isolated carboxyl groups); 1640–1632 (H–O–H bend, liquid water); 1400–1370 (non-carboxyl C–O–H in-plane bend and CH2 deformation); 1103 (non-carboxyl C–O stretch); 1060 (in-plane C–H bend, non-aromatic hydrocarbons and carbohydrates); 940 cm−1 (out-of-plane carboxyl C–O–H bend). DRIFT provides the maximum number of bands and is capable of measuring hydrogen-bonded bands and CHx groups. ATR provides the good sensitivity for water and C–H/C–C bands in the range 2000–400 cm−1. FTIR–PAS reveals less bands than DRIFT but more intense bands than ATR–FTIR and shows the maximum sensitivity for absorption bands that do not appear in ATR-IR spectra and are expedient for supporting either DRIFT or FTIR–PAS along with depth-profiling. Thus, all three modalities are required for the full characterization of nanodiamonds surface functional groups.

Diffuse Reflectance Infrared Spectroscopic Characterization of Silica Dehydroxylation

1990 ◽  
Vol 44 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Robert L. White ◽  
Aurobindo Nair
Keyword(s):  
Force Constant ◽  
Diffuse Reflectance ◽  
Spectroscopic Characterization ◽  
Absorption Bands ◽  
Stretching Vibration ◽  
Diffuse Reflectance Infrared ◽  
Highly Strained ◽  
Infrared Absorption Bands ◽  
Absorbance Band

Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) is employed to study the dehydroxylation of amorphous silica. Dehydroxylation results in the appearance of infrared absorption bands at 1022, 1107, and 1240 cm−1 assigned to asymmetric stretching vibrations for three different siloxane bridge types. The 1107-cm−1 absorbance band represents a siloxane bridge that is indistinguishable from bulk species. The 1022-cm−1 absorbance band represents a siloxane bridge with a bond angle that is smaller than the bulk, with little change in the stretching vibration force constant. The 1240-cm−1 absorbance band derives from a siloxane bridge characterized by a stretching force constant significantly larger than that of bulk siloxane bridges. This band may be indicative of a highly strained or broken siloxane bridge.

Diffuse reflectance spectroscopy of Pu ions in zirconolite and perovskite

2004 ◽  
Vol 824 ◽  
Author(s):  
E. R. Vance ◽  
K. S. Finnie ◽  
Y. Zhang ◽  
B. D. Begg
Keyword(s):  
Electronic Absorption ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Diffuse Reflectance Spectroscopy ◽  
Charge Compensation ◽  
Reflectance Spectroscopy ◽  
Visible Range ◽  
Absorption Bands ◽  
Ambient Temperatures ◽  
Polycrystalline Ceramic

AbstractDiffuse reflectance spectroscopy measurements at ambient temperatures have been made over the near infrared-visible range (5000-25000 cm−1) on polycrystalline ceramic zirconolite (CaZrTi2O7) and perovskite (CaTiO3) samples doped with Pu4+. The Pu concentrations were varied between 0.001 and 0.1 formula units. The Pu ions gave rise to a number of unresolved intraconfigurational f-f electronic absorption bands of a few hundred cm−1 bandwidth. Pu ions were targeted to substitute in the Ca sites as either trivalent or tetravalent species and as tetravalent species in the Zr site of zirconolite by the appropriate choice of charge compensation and firing atmosphere. There was approximate agreement of the Kubelka-Munk absorption intensities with Beer's Law for the different Pu4+ substitution schemes, apart from some “new” bands, attributed to impurities, observed in the most dilute zirconolite sample. No clear spectral differences were evident when Pu4+ was targeted to Ca or Zr sites in zirconolite. Samples prepared in reducing atmospheres with a view to producing Pu3+ were strongly absorbing, leading to suppression of Pu transitions.

scholarly journals Image-based metric heritage modeling in the near-infrared spectrum

2020 ◽  
Author(s):  
Efstathios Adamopoulos ◽  
Alessandro Bovero ◽  
Fulvio Rinaudo
Keyword(s):  
Near Infrared ◽  
Three Dimensional ◽  
Visible Spectrum ◽  
Lighting Conditions ◽  
Image Based Modeling ◽  
Spectral Models ◽  
Software Implementations ◽  
Automatic Software ◽  
Accuracy Of Results

Abstract Digital photogrammetry and spectral imaging are widely used in heritage sciences, towards the comprehensive recording, understanding, and protection of historical artefacts and artworks. The availability of consumer-grade modified cameras for spectral acquisition, as an alternative to expensive multispectral sensors and multi-sensor apparatuses, along with semi-automatic software implementations of Structure-from-Motion (SfM) and Multiple-View-Stereo (MVS) algorithms, has made more feasible than ever the combination of those techniques. In the research presented here, the authors assess image-based modeling from near-infrared (NIR) imagery acquired with modified sensors, with applications on tangible heritage. Three-dimensional meshes, textured with the non-visible data, are produced and evaluated. Specifically, metric evaluations are conducted through extensive comparisons with models produced with high-resolution visible (VIS) spectrum image-based modeling, to check accuracy of results. Furthermore, the authors observe and discuss, when the implemented NIR modeling approach, enhances the preservation of surface detail on the reconstructed spectral models or counteracts certain problems arising from lighting conditions during VIS acquisition. Radiometric properties of the produced results are evaluated on the capacity to enhance observation towards the characterization of surface and under-surface state of preservation, and consequently, to support conservation interventions, in comparison to the respective results in visible spectrum.

Infrared Microsampling by Diffuse Reflectance Fourier Transform Spectrometry

1980 ◽  
Vol 34 (5) ◽  
pp. 533-539 ◽  
Author(s):  
Michael P. Fuller ◽  
Peter R. Griffiths
Keyword(s):  
Fourier Transform ◽  
Thin Layer ◽  
Diffuse Reflectance ◽  
Absorption Bands ◽  
Fourier Transform Spectrometry ◽  
Increased Sensitivity ◽  
Intense Absorption ◽  
Diffuse Reflectance Infrared ◽  
Layer Chromatography

It is shown that diffuse reflectance techniques enable increased sensitivity to be obtained for infrared microsampling compared with the use of KBr micropellets. When nonabsorbing matrices, such as KCl, are used, detection limits of less than 10 ng of samples are observed. Samples absorbed on graphitized substrates, which have a fairly strong general absorption but few intense absorption bands, may also be studied but at somewhat reduced sensitivity. Diffuse reflectance infrared Fourier transform spectrometry does not appear to be particularly useful for studying adsorbates on silica gel, which is not only a strong infrared absorber but also has a surface which is so active that small changes in the surface structure can change the spectrum significantly. Extraction of sample spots from thin layer chromatography plates followed by deposition onto KCl yields much better results than in situ measurements.

scholarly journals Assessing the stability of surface lights for use in retrievals of nocturnal atmospheric parameters

2020 ◽  
Vol 13 (1) ◽  
pp. 165-190 ◽  
Author(s):  
Jeremy E. Solbrig ◽  
Steven D. Miller ◽  
Jianglong Zhang ◽  
Lewis Grasso ◽  
Anton Kliewer
Keyword(s):  
Near Infrared ◽  
Correlation Coefficients ◽  
Visible Spectrum ◽  
Light Sources ◽  
Strongly Correlated ◽  
Spatially Resolved ◽  
Relative Standard ◽  
Geometric Variables ◽  
The Stability

Abstract. The detection and characterization of aerosols are inherently limited at night because the important information provided by visible spectrum observations is not available and infrared bands have limited sensitivity to aerosols. The VIIRS Day–Night Band (DNB) onboard the Suomi-NPP satellite is a first-of-its-kind calibrated sensor capable of collecting visible and near-infrared observations during both day and night. Multiple studies have suggested that anthropogenic light emissions such as those from cities and gas flares may be useable as light sources for the retrieval of atmospheric properties, including cloud and aerosol optical depth. However, their use in this capacity requires proper characterization of their intrinsic variation, which represents a source of retrieval uncertainty. In this study we use 18 months of cloud-cleared VIIRS data collected over five selected geographic domains to assess the stability of anthropogenic light emissions and their response to varied satellite and lunar geometries. Time series are developed for each location in each domain for DNB radiance, four infrared channels, and satellite and lunar geometric variables, and spatially resolved correlation coefficients are computed between DNB radiance and each of the other variables. This analysis finds that while many emissive light sources are too unstable to be used reliably for atmospheric retrievals, some sources exhibit a sufficient stability (relative standard deviation <20 %). Additionally, we find that while the radiance variability of surrounding surfaces (i.e., unpopulated land and ocean) is largely dependent on lunar geometry, the anthropogenic light sources are more strongly correlated with satellite viewing geometry. Understanding the spatially resolved relationships between DNB radiance and other parameters is a necessary first step towards characterizing anthropogenic light emissions and establishes a framework for a model to describe variability in a more general sense.

scholarly journals Detecting the NIR Fingerprint of Colors: The Characteristic Response of Modern Blue Pigments

Heritage ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 2255-2261 ◽  
Author(s):  
Yivlialin ◽  
Galli ◽  
Raimondo ◽  
Martini ◽  
Sassella
Keyword(s):  
Diffuse Reflectance ◽  
Near Infrared ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Composite Sample ◽  
Model Composite ◽  
Non Invasive ◽  
Uv Visible ◽  
Invasive Techniques

Reflectance spectroscopy in the ultraviolet (UV), visible (Vis), and near infrared (NIR) range is widely applied to art studies for the characterization of paints and pigments, with the advantages of non-invasive techniques. Isolating and detecting the fingerprint of pigments, especially in the NIR range, is quite challenging, since the presence of vibrational transitions of the most common organic functional groups prevents to relate the optical spectrum of a composite sample, as an artwork is, to each one of its elements (i.e., support, binder, and specific pigment). In this work, a method is presented to obtain the UV-Vis-NIR optical response of the single components of a model composite sample reproducing an artwork, i.e., the support, the binder, and the pigment or dye, by using diffuse reflectance spectroscopy. This allowed us to obtain the NIR spectral fingerprint of blue pigments and to identify specific features possibly applicable for detecting cobalt and phthalocyanine blue colors in artwork analysis.

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