UV-vis transmission spectra

Fig. 9.17 UV/VIS transmission spectra of neat PLA and nanocomposite (PLANCl.7). Reprinted from [57], 2004 WILEY-VCH.

To determine the optical band gap UV/Vis transmission spectra between 220 and 750 nm (1.5 eV - 2.95 eV) of single crystals are measured at room temperature by use of a micro spectrophotometer Leica MSP-SP. Figure 3 shows the UV/Vis spectra of the four cetineite-phases (spectral resolution 1 nm). 

Fig. 11.4 (a) UV-vis transmission spectra of 10-cycle ZlF-8 film grown on glass substrate after exposure to propane of various concentrations from 0 to 1(X) % and (b) corresponding interference peak (originally at 612 nm) shift vs. propane concentration. The propane concentration is expressed as a percentage of the total gas flow where nitrogen is used as diluents (Reprinted with permission from Lu and Hupp 2010, Copyright 2010 American Chemical Society)... 

FIGURE 20.8 Ultra violet-visihle light (UV-Vis) transmission spectra of S sample during ON-OFF states switching at an applied electrical field of 200 V. ... 

From now on, we adopt a notation that reflects the chemical nature of the data, rather than the statistical nature. Let us assume one attempts to analyze a solution containing p components using UV-VIS transmission spectroscopy. There are n calibration samples ( standards ), hence n spectra. The spectra are recorded at q wavelengths ( sensors ), digitized and collected in an nx.q matrix S. The information on the known concentrations of the chemical constituents in the calibration set is stored in an nxp matrix C. Each column of C contains the concentrations of one of the p analytes, each row the concentrations of the analytes for a particular calibration standard. 

SnC>2 nanoparticles have been successfully synthesized by chemical co-precipitation method using ethanol, acetone, tetrahydrofuran (THF) and ether as solvents. X-ray Diffraction (XRD), Field Emission Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) have been used to study the crystallographic and morphological properties of synthesized SnC>2 nanoparticles, while their optical properties have been studied by UV-Visible absorption spectroscopy. UV-Vis absorption spectra shows a weak quantum confinement in all the synthesized SnCL samples. The photo-catalytic activity of as-synthesized SnC>2 nanoparticles under UV irradiation has been evaluated using Methylene Blue (MB) dye as a test contaminant in water. The results showed that solvents played a key role to control the morphology and photo-catalytic activity of SnCE nanoparticles. 

Photoluminescence spectra were recorded with a Perkin-Elmer LS-55 spectrometer while the UV-vis absorption spectra were recorded with UV/VIS/NIR Perkin-Elmer spectrometer. Transmission electron microscope (TEM) images were obtained using a JOEL JEM 3010 instrument. Infrared spectra were recorded with a Bruker IFS-66v spectrometer. 

Figure 2. Transmission and reflection UV- Vis-NIR spectra of the free-standing polyimide films.

Fig. 2 - Part (a) ftom bold to dotted curves, evolution of the UV-Vis spectra, collected in transmission mode, of the NaaPdCh bare mother solution (3.2-10" M) as a function of the pH increase (only a selection of curves has been reported). Part (b) as part (a) for the Na2PdCU solution previously acidified with HCl down to pH = 1.4. Both insets report absorption intensity of the two main CT components as a function of pH (triangles and squares refer to the high and low frequency component, respectively). Part (c) UV-Vis DRS spectra of the precipitates obtained from the two solutions analyzed in parts (a) and (b), grey and black curve, respectively. Part (d) XRD pattern of the precipitate phase from the bare mother solution, a.u. = absorbance imits K-M u. = Kubelka-Munk units.

UV/vis absorption spectra were recorded on a Shimadzu UV-3100 spectrophotometer. Powder X-ray diffraction measurements were carried out on a Scintag XDS-2000 powder diffraction system. Transmission electron microscopy (TEM) images were obtained on Hitachi 7000 and Hitachi HF-2000 TEM systems. 

Figure 8.2 The UV-vis-NIR spectra observed for PANI in its emeraldine base (EB) and salt (ES) forms (see the schematic structure). Above the spectra are presented the energy diagram for PANI-EB and PANI-ES. The UV-vis-NIR spectra were acquired using a Shimadzu UVPC-3101 scanning spectrophotometer in transmission mode with 1 mm quartz cell PANI-EB was dissolved in N-methyl-pyrrolidone and PANI-ES was dissolved in concentrated EICI...

Having established that the multi-wavelength transmission techniques offer a number of advantages, the Uv-vis reflectance spectra from concentrated polystyrene lattices have been recorded using fiber optics reflection probes. Although some averaging of the individual particle properties can be expected, reliable calibration and estimation of the particle properties is possible, since discrimination to the desired particle properties is found as it will be shown below. 

Color measurement In the case of colored toners, UV and visible (UV-Vis) transmission spectroscopy is successfully applied. If an isolated toner particle of cyan, magenta, yellow, and black is available on a document, the problem of color separation is irrelevant. However, in routine cases, color separation must be practiced under a microscope. The various colored toner particles, composing a colored image, are isolated, embedded in glycerin, and placed on a quartz slide. The UV-Vis spectra are measured using a microspectrophotometer that provides a more objective measure of colors, compared to the subjective evaluation of the naked eye or the use of an optical microscope alone. 

In general UV/vis absorption spectra of SAMs are difficult to measure because of the extremely low surface concentration of the chromophore, which leads to very low absorbances. Therefore, only dyes with rather high molar absorptivities, such as porphyrins, have been accurately characterised in this way. Virtually all studies were performed in transmission mode using thin, optically transparent gold layers on glass etc. because of the better background compensation compared to reflectance mode measurements. 

Fig. 34 UV/vis absorption spectra of a porphyrin chromophor 31 on Au/glass in transmission mode (solid line, red shift) and in dichloromethane (dotted line). Reprinted with permission from [142]. Copyright (2000) American Chemical Society...

Figs. 3 7. 3-8. 3-9 Transmission and Reflectance UV-Vis-NIR spectra for the same CP, a coarse-particulate, and a long chain-length poly(aromatic amine). 3i7 Lefty Transmission-mode. Fig. 3-8 Eighty Specular Reflectance. 3i9 Bottomy Diffuse Reflectance, data Courtesy of Ashwin -Ushas Corp., Inc. 

UV-vis absorption spectra of the samples were recorded with JASCO V-550 in a transmission mode. 

UV-VIS extinction spectra were measitred with a Lambda 35 spectrophotometer (Perkin Elmer, USA). Particle size distribution, based on hydrodynamic diameter, was evaluated by Nano S (Malvern, UK), a dynamic light scattering analyzer (DLS). Urueacted metal cations, extracted from the sample by a semi-permeable osmotic membrane (Visking tube), were detected by ICP-AES qirantitative analysis (Liberty 200, Varian, Austraha) in order to determine the reaction yield. Suspensiorts were dropped and dried on a copper grid, then observed by high resolution transmission electron microscopy (HRTEM) (Tecnai F20) and by the STEM mode with microanalysis EDX. 

Ag-core/Au-shell bimetallic nanoparticles were prepared by NaBH4 reduction method [124]. UV-Vis spectra were recorded and compared with various ratios of AuAg alloy nanoparticles. The UV-Vis spectra of bimetallic nanoparticles suggested the formation of core/shell structure. Furthermore, the high-resolution transmission electron microscopy (HRTEM) image of the nanoparticles confirmed the core/shell type configuration directly. 

Spectroscopic evaluation of the catalysts. The UV-Vis spectra of the Jacobsen Co-salen catalysts were collected in the transmission mode on a CARY-3E UV-Vis spectrophotometer by dissolving the catalysts in epichlorohydria The Co K-edge (7709 eV) X-ray absorption near edge stracture, XANES, of Jacobsen s Co-salen catalyst was collected during the HKR reaction at beamline XIO-C at National Synchrotron Light Source (NSLS), Brookhaven National Lab, Upton, NY. 

Table 5.5 shows the main characteristics of UV spectrophotometry as applied to polymer/additive analysis. Growing interest in automatic sample processing looks upon spectrophotometry as a convenient detection technique due to the relatively low cost of the equipment and easy and cheap maintenance. The main advantage of UV/VIS spectroscopy is its extreme sensitivity, which permits typical absorption detection limits in solution of 10-5 M (conventional transmission) to 10 7 M (photoacoustic). The use of low concentrations of substrates gives relatively ideal solutions [20]. As UV/VIS spectra of analytes in solution show little fine structure, the technique is of relatively low diagnostic value on the other hand, it is one of the most widely used for quantitative analysis. Absorption of UV/VIS light is quantitatively highly accurate. The simple linear relationship between... 

Figure 10.2 UV/Vis spectra for (a) RuCb in ethanol, (b) Ru2(p-cymene)2Cl4 in CH2CI2, (c) 1 in CH2CI2, (d) the supported Ru complex 3, (e) the unsaturated Ru complex (5) activated by 02/iBA and (f) the supported Ru catalyst after 100 cycles of stilbene epoxidation. Spectra (a)-(c) were measured in a transmission mode (left-hand axis abs) and (d)-(f) in a diffuse reflectance mode (left-hand axis KM).

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