UV-VIS diffuse reflectance spectra

Fig. 1. UV-vis diffuse reflectance spectra of neat Ti02, chemically-modified and Ti02-loaded MCM-...

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. 

Samples were characterized by FTIR spectroscopy with a Perkin Elmer (Spectrum BX) spectrometer using KBr pressed disks as matrices. The DRIFT experiments were carried out with a Broker IFS 55 spectrometer equipped with a Thermo Spectra Tech reacting cell. UV-vis Diffuse Reflectance spectra were recorded on a Perkin Elmer Lambda 45 spectrophotometer equipped with a diffuse reflectance attachment. Raman spectra were collected with Perkin Elmer system 2000 NIR FT-Raman using as excitation radiation the 5th harmonic of a diode pumped Nd YAG laser (1065 nm). 

Fig. 7.13 UV-VIS diffuse reflectance spectra of modified and pure samples (a) Ti02, (b) C Ti02, (c) physical mixture of Ti02 and hydrothermal carbon and (d) pure carbon.

Figure 1 reports the corresponding UV-Vis Diffuse Reflectance spectra. The band at 400 nm is relative to the CT between and its intensity was proportional to the amount of On the other hand, the intensity of the band at 900 nm decreased, relative to a d-d transition for in the vanadyl moiety. The XRD pattern of all samples, but ox3, corresponded to that of well-crystallized VPP in the case of sample ox3, additional reflections were due to the presence of 5-VOPO4 (JCPDS 37-0809). Therefore, the treatment of the VPP led to the generation of surface in samples oxl and ox2, and to the growth of crystalline VOPO4 in sample ox3. 

Raman spectra were taken on a home built system, composed of Spectra-Physics 2020 series lasers, coupled with a Dilor XY-800 triple spectrometer and a Whight Instruments nitrogen cooled CCD. All samples were measured at room temperature in a backscattering configuration, with 514.53 nm Ar+ laser excitation. The laser power was tuned between 1 mW and 30 mW. UV-VIS diffuse reflectance spectra were taken on a Varian Cary 5 spectrophotometer, equipped with a specially designed Praying Mantis diffuse reflectance attachment of Harrick. 

Fig. 5 shows the UV-VIS diffuse reflectance spectra for the Ti-MCM-41 samples. In this figure, a strong band at ca. 220 nm, which has been assigned to isolated framework titanium in tetrahedral coordination, is observed for the sample of higher Si/Ti mole ratios. Ti-MCM-41 synhesized at the lower Si/Ti mole ratio(40) showed a broad shoulder at ca. 270nm. This band is attributed to the extraframework titanium. In contrast. Ti-MCM-41 with a low titanium content proved to be free of occluded TiO, in the pores. Thus this result indicates that the rapid evaporation method is favorable for the synthesis of Ti-MCM-41 to incorporate the titanium into the framework. 

Fig. 2. UV-Vis diffuse reflectance spectra F g-3- Gravimetric curves of of mesoporous WO /ZrO samples. thermodesorption of ammonia from...

Diffuse reflection spectroscopy (UV-DRS). UV-Vis diffuse reflectance spectra were recorded in a Varian Cary 5 spectrophotometer (Harrick Scientific) with a diffuse reflectance accessory of Praying Mantis geometry. The samples were set in holds with 2 mm thickness. The spectra were recorded in the 200 nm and 800 nm range with a scanning speed of 1800 mm.min at room temperature against supports as reference. 

Figure 4. UV-Vis diffuse reflectance spectra of platinum cantaLoing SBA-15 (calcined at 300 °C) curve l-Pt/SBA-15, WJ ([PtCy used as a Pt precursor) and curve 2- Pt/SBA-15, DP ([Pt(NH3)4] used as a R precursor)...

Fig. 4 (A, B) Typical SEM images of as-prepared AgOAgCl sample (C) UV/Vis diffuse-reflectance spectra of (a) AgCl, (b) Ag AgCl, and (c) N-doped Ti02 (D) Photodecomposition of MO dye in solution (20 mg over AgOAgCI ( ] and N-doped Ti02 (A) under...

The synthesized M0O3 byproduct can be dissolved in excess HCl solution, and the morphology of final Ag(l)AgCl products was influenced by the structure of the precursors. The UV-vis diffuse reflectance spectra indicated that all the Ag AgCl samples showed a strong and wide absorption... 

Fig. 19 (A) Typical SEM image of cube-like Ag/AgCl (B) UV-vis diffuse reflectance spectra of as-prepared AgCl and Ag/AgCl (C) Photocatalytic degradation...

Fig. 12. In situ UV-Vis diffuse reflectance spectra of 0.5 wt% Cr/Si02 catalyst treated at 623 K in 2% isobutane in N2 as a function of time. Reprinted from Ref 89, copyright 2000, with kind permission from Elsevier.

UV-Vis diffuse reflectance spectra were obtained with the reflectance attachment of a CARY 1756 spectrometer connected to a Hewlett Packard computer. The spectra were recorded between 210-700 nm using BaS04 as reference. 

UV-Vis diffuse reflectance spectra of the Rh/L polymer showed one intense absorption maximum at 400nm, close to that observed with ] (CNI%)4BFh4 monomer [20] and a board absorption band centred at 700nm-750nm, which is characteristic of weak intrachain Rh.Rh interaction in polymers [18, 21] such as [Rh(diisocyanide)2 d ] . These electronic absorptions were asi ed to the transition between energy levels in the bonding and A2 (p2p ) antibonding orbitals. The intensity of the above peaks decreases for... 

Fig. 45. Ag-clinoptilolites, natural and synthetic, (a) UV-vis diffuse reflectance spectra of natural (Ag-NC) and synthetic (Ag-SC) clinoptilolites reduced at 100 °C and (b) 400 °C [05C2].

Fig. 4 (a) Plots of CO evolution turnover number versus time in the photocatalytic CO2 reduction with 4 and the homogeneous control, (b) FT-IR of 4 before and after photocatalysis, (c) PXRD patterns of 4 before and after photocatalysis. The simulated PXRD for the UiO-67 is also shown, (d) UV-vis diffuse reflectance spectra of 4 before and after photocatalysis. Reprinted with permission from [35]. Copyright 2011 American Chemical Society... 

Fig. 3 left) UV-vis. diffuse reflectance spectra and right) the residual concentration of RhB solution after UVA is photodecomposition by Ti-EDTMP, Ti-HEDP, PT and Ti02. 

Figure 18 Inverse opals based on Zr02 with pore sizes between (A) 200, (B) 250, (C) 285 nm, (D) sample B with methanol, and (E) sample C with methanol and the corresponding UV-vis diffuse reflection spectra. Reprinted with permission from Aguirre et al (2010). Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim.

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