UV-visible reflectance spectra

Fig. II. UV-Visible reflectance spectra (Kubelka-Munk function vs. wavenumber) of (a) silicalite-1 (b) TS-1. (From Boccuti et al., 1989.)...

Figure 2. UV-visible reflectance spectra of (8-2n)Na,2nAg,2Br-SOD with varying silver concentrations. Ag+/uc (a) 0 (b) 0.05 (c) 0.28 (d) 2.0 (e) 3.1 (f) 8.0 (g) bulk AgBr (h) (8-2n)Na,2nAg,2Cl-SOD, 0.1 Ag+/uc (i) (8-2n)Na,2nAg,2Br-sodalite, 0.1 Ag+/uc (j) (8-2n)Na,2nAg,21-SOD, 0.1 Ag+/uc. Note that band-gap absorptions for 8Na,2X-SOD expanded insulators peak at 192 (Cl), 208 (Br), and 214 nm (I) (Figure 2h,i,j) and parallel the order for the bulk fee NaX materials, 138 (Cl), 165 (Br), and 211nm (I), respectively, (k) Schematic band diagram for expanded AgX semiconductors (Reprinted from ref. 3. Copyright 1990 American Chemical Society.)...

Claesson, Olson and Wennerblom (8) carried out the earliest studies on the effect of near-uv irradiation on the uv-visible reflectance spectra of high-yield spruce bisulphite liner and newsprint. In this work, the relative reflectivity (equation 1) of samples was plotted against wavelengths in the range 300 to 600 nm (8). 

Figu re 5.6 Representative concentration-dependent changes of HOM-TPPS cage chemosensor sink in the color map and in UV-visible reflection spectra of [Hg-TPPS]" complex formation at X = 447nm, with the addition of various concentrations of Hg(ll)... 

The rapid metal-to-ligand binding kinetics with formation of the [Hg-TPPS]", [Sb-PR] , [Cd-TMPyP] and [Pb-(DZ)2] complexes was investigated by continuously monitoring the UV-visible reflectance spectra (Figure 5.13) and the color change of the nanosensors after addition of Hg, Sb, Cd " and Pb ions as a function of time. The results showed that charge transfer between the TPPS, PR,... 

Figure 2. Diffuse reflectance UV-visible absorption spectra recorded as a function of time after the mixing of solid DPB and H0 57ZSM-5 (a) and after of solid DPB and H6 6ZSM-5 (b)...

The uv-visible difference spectra of newsprint and wood irradiated at 365 nm are quite different from those of high-yield bisulphite liner. The relative reflectivity of newsprint and wood increases at about 360 nm and decreases at about 430 nm. After 1 hour irradiation, the relative reflectivity of newsprint at 430 nm does not decrease further. 

The poly(3, 4 -alkylterthiophene), PTT (2) used in our studies is prepared by FeCl3-mediated oxidative coupling polymerization [39]. PTT with a long alkyl side-chain (R > C6) for example PTT-10 (2, R = n-Ci0H2i) has an ability to self-organize in the solid state as reflected by a bathochromic shift in its UV-visible absorption spectra from solution to thin film (Fig. 4.1a). The solution spectrum of PTT-10 also has a progressive bathochromic shift with concomitant appearance of a longer-... 

The solution UV-vis spectra of the monomeric clathrochelate tin-, germanium-, and antimony-capped complexes (Tables 23 and 25) and the UV-vis reflection spectra of the germanium-capped polymeric clathrochelates (Table 22) are appreciably different from those for the FeD3(BR)2 complexes and resemble the spectra for iron(II) tris-phenanthrolinates and tris-bipyridinates [236]. In the visible region, two metal-ligand CTBs at 17 560-18 480 and 20 560-21 320 cm i... 

Electronic spectroscopy, often referred to as UV/visible spectroscopy, is a useful instrumental technique for characterising the colours of dyes and pigments. These spectra are obtained from appropriate samples using a spectrophotometer operating either in transmission (absorption) or reflection mode. UV/visible absorption spectra of dyes in solution, such as that illustrated in Figure 2.3, are useful anal3Tically, qualitatively to assist the characterisation of the dyes and as a sensitive method of quantitative analysis. They also provide important information to enable relationships between the colour and the molecular structure of the dyes to be developed. 

The samples were characterized by UV-visible reflectance spectroscopy using a Varian-Carry-5 spectrometer equipped with a double monochromator. Diffuse reflectance spectra were recorded in air at room temperature in the range 200-800 nm against alumina as reference. Spectra are presented indicating the frequency of the Schulz-Munk-Kubelka equation as function of the wavelength. 

Modulated Infrared Reflectance Spectroscopy -EMIRS-, and electronic spectra for UV-visible Reflectance Spectroscopy -UVERS-). Experimental set-ups are also presented for each technique. 

In this paper, the basic principles of reflectance spectroscopy will be first discussed, emphasizing what is particular to each method electronic spectra for UV-visible Reflectance Spectroscopy (UVERS), vibrational fingerprints for Electrochemically Modulated Infrared Reflectance Spectroscopy (EMIRS). After a short presentation of the experimental set-up for each technique, various examples, taken mainly from our laboratory, will be given. 

Unlike Raman or infrared spectroscopy, with their well-defined capability of determining vibrational properties, the application of optical spectroscopy in the UV-visible range is less focused. This is because UV-visible reflectance spectroscopy intrinsically is to yield electronic excitation spectra, which unfortunately for solids are often broad and unstructured and hence not very informative as such. Therefore, this technique has increasingly been used for other tasks also, such as the determination of coverages, the assessment of structural information, and the study of surface roughness. The aim of this chapter was to demonstrate this versatility. 

These unusual photophysical properties shown by ZnTPP confined in the Cd domain indicate that microenvironments about the ZnTPP species in the Cd domain are considerably different from those in the La domain. This difference in the microenvironment is also reflected in the UV-visible absorption spectra The Soret band profile in the Cd domain is broader than that in the La domain [83]. 

The PLM can be used in a reflection or a transmission mode. With either mode, light of various wavelengths from ultraviolet to infrared, polarized or unpolarized, is used to yield a wide variety of physical measurements. With just ordinary white light, a particle or any object detail down to about 0.5 p.m (500 nm) in diameter can be observed to detect shape, size, color, refractive index, melting point, and solubiUty in a group of solvents, all nondestmetively. Somewhat larger particles yield UV, visible, or IR absorption spectra. 

The similarity in the electronic structures of the eight r-electron systems R2PN3S2 (3.25) and [S3N3O2] (3.26) is also reflected in their UV-visible spectra. Both these heterocycles have an intense purple colour due to a visible band at ca. 560 nm attributed to the HOMO (tt )... 

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. 

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