Hydroxide DRIFTS spectra

Diffuse reflectance IR spectroscopy (DRIFT) was, furthermore, successfully employed in studying molecular sieves of the new generation [957] such as aluminophosphates (AlPOs) and silicoaluminophosphates (SAPOs). Thus, Zscherpel et al. and Loeffler et al. [563,564] studied by DRIFT the range of fundamental OH stretching, OH deformation and framework vibrations of AIPO4-18 (upon decomposition of the template, tetraethylanunonium hydroxide), the fundamental and combination vibrations of hydroxy groups of SAPO-5 and SAPO-17 as well as the framework region of SAPO-34. In the latter case a comparison was made with the transmission spectrum. 

Spectra collected by these fom methods of an oxidized layer on 50-70-p,m galena particles (natural PbS, n 4) using the same number of scans (100) and resolution (4 cm ) and a Perkin-Ehner 1760X FTIR spectrometer equipped with a mercury-cadmium-teUmium detector are shown in Fig. 2.51. Because of strong backscattering by the PbS particles and, as a result, a small penetration depth of radiation, the transmission spectrum obtained from the powder squeezed between two plane-parallel KBr plates represents mainly the component /q that has passed by the particles (Fig. 1.22) and, hence, bears no information on the sample absorption. The DRIFTS and DTIFTS spectra of the PbS powder and the transmission spectrum of a mixture of PbS and KBr spectra are more informative. The distinct absorption bands of surface oxidation products at 1440, 1400, and 1200-1100 cm are assigned to lead carbonate, hydroxide, and sulfoxide [109],... 

Figure 6.1 DRIFTS spectra (samples diluted to 5% w/w in finely ground KBr) showing the interaction of isostearic acid with aluminum hydroxide (a) aluminum hydroxide (Alcan SFl 1-E) treated with about 0.7 monolayers of isostearic acid, (b) untreated aluminum hydroxide reference substrate, and (c) substrate subtracted spectrum (i.e., (a-b) multiplied by 5 to enhance peaks) showing (i) C—H stretching...

Figure 3.18 DRIFTS infra-red difference spectrum of magnesium hydroxide subtracted from magnesium hydroxide coated with MPBD...

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