Ultraviolet/visible diffuse reflectance

The progressive increase in the extent of POM reduction, as evidenced by the ultraviolet visible diffuse reflectance (UV-vis DR) spectra of catalysts downloaded after different reaction times during catalyst equilibration. 

The simultaneous application of EPR/ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS)/online gas chromatography (GC) to characterize working catalysts was realized a few years ago 14), and laser-Raman spectroscopy has recently been coupled with these to provide the first such simultaneous application of three techniques 15). 

Brittain, H.G. (1995) Ultraviolet/visible diffuse reflectance spectroscopy. Drugs Pharm. Sci., 70, 37-58. 

As seen in Fig. 9.8, ultraviolet-visible diffuse reflection (UV-Vis) spectra shows a strong absorption band from 275 to 500 nm, which is derived from the 4/ 5d transition of Eu " ions [39]. In addition. Fig. 9.8 shows the photoluminescence excitation (PLE) and photoluminescence emission (PL) of NaBaScSi2O7 0.1Eu phosphor. The PLE spectmm indicates the typically broad... 

UV—vis DRS ultraviolet—visible diffuse reflectance spectroscopy XAS X-ray absorption spectroscopy XPS X-ray photoelectron spectroscopy XRD X-ray diffraction... 

The metal content analysis of the samples was effected by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES Varian Liberty II Instrument) after microwaves assisted mineralisation in hydrofluoric/hydrochloric acid mixture. Ultraviolet and visible diffuse reflectance spectroscopy (UV-Vis DRS) was carried out in the 200-900 nm range with a Lambda 40 Perkin Elmer spectrophotometer with a BaS04 reflection sphere. HF was used as a reference. Data processing was carried out with Microcal Origin 7.1 software. 

Ultraviolet-visible (UV-vis) diffuse reflectance spectra of supported WOx samples and standard W compounds were obtained with a Varian (Cary 5E) spectrophotometer using polytetrafluoroethylene as a reference. The Kubelka-Munk function was used to convert reflectance measurements into equivalent absorption spectra [12]. Spectral features of surface WOx species were isolated by subtracting from the W0x-Zr02 spectra that of pure Z1O2 with equivalent tetragonal content. All samples were equilibrated with atmospheric humidity before UV-vis measurements. 

With the exception of single-crystal transmission work, most solids are too opaque to permit the conventional use of ultraviolet/visible (UV/VIS) electronic spectroscopy. As a result, such work must be performed through the use of diffuse reflection techniques [8-10]. Important work has been conducted in which UV/VIS spectroscopy has been used to study the reaction pathways of various solid state reactions. Other applications have been made in the fields of color measurement and color matching, areas which can be of considerable importance when applied to the coloring agents used in formulations. 

The intensities of diffuse reflectance and fluorescence are both distributed over the solid angle according to Lambert s cosine-law. An ultraviolet-visible (UV/VIS)-... 

Spectroscopy. - In the following paragraphs we discuss how various spectroscopy tools have been used to illuminate the rich surface chemistry of supported polynuclear metal complexes. These methods include infrared (both diffuse reflectance and transmission), ultraviolet and visible (UV-Vis), x-ray photoelectron spectroscopy (XPS), and x-ray absorption, near edge spectroscopy s (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy s. 

This section summarizes the chemistry of the SC isobutane regeneration process. To understand the nature of the hydrocarbons that remain adsorbed on the surface of the USY zeolite catalyst both before and after SC isobutane regeneration, a series of ex-situ temperature-programmed oxidation (TPO), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and ultraviolet-visible (UV-vis) analyses was performed on samples submitted to different TOS 10 under isobutane/butene reaction conditions. 

Diffuse reflectance (DR) spectroscopy of Co permits the observation of d-d transitions in the near infrared and visible region and charge transfer (CT) transitions in the ultraviolet region. Co is the only common d ion and because of its stereochemistry the respective... 

Several spectroscopic and nonspectroscopic techniques may be used to study the bonding nature of the adsorbate to the surface [2a, 4]. In the first case we want to emphasize the importance of diffuse reflectance techniques for absorption and emission studies in the ultraviolet (UV), Visible (Vis), and near infrared (NIR) spectral ranges. X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. In the second group, we refer the heat adsorption and the isotherm adsorption techniques, among others. 

Luan Z, Kevan L. Electron spin resonance and diffuse reflectance ultraviolet-visible spectroscopies of vanadium immobilized at surface titanium centers of titanosihcate... 

FIGURE 3,29 Optical diffuse reflectance spectra of carbon-coated Ti02 (refer to Table 3.6) (a) in a region from ultraviolet to visible light (b) in ultraviolet region. 

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