KBr-technique

In Fig. 2.1.6.6, the FTIR spectra of the Jacobsen ligand (a), the Jacobsen catalyst (bj, and the immobilized manganese salen complex in the cages of dealuminated faujasite zeolite (c) are compared. While spectra a and b have been measured using the standard KBr technique, the spectrum c of the ship in a bottle catalyst has been recorded using a self-supported wafer. The bands at wavenumbers 1466 cm, 1434 cm" , 1399 cm" and 1365 cm" in spectrum c can be assigned to the... 

The use of KBr disks or pellets has often been avoided because of the demanding task of making good pellets. Such KBr techniques can be less formidable through the Mini-Press, which affords a simple procedure the KBr-sample mixture is placed in the nut portion of the assembly with one bolt in place. The second bolt is introduced, and pressure is applied by tightening the bolts. Removal of the bolts leaves a pellet in the nut that now serves as a cell. 

Crystalline or solid samples (ca. 10 mg) are ground with 5 drops of nujol in an agate mortar to form a paste for subsequent CD or MCD measurement. Perfluoro-butadiene can also be used instead of nujol. Otherwise, the KBr pellet technique, for which KBr and sample should be completely dried in vacuo and ground into a fine powder, can be used conveniently. On using the KBr technique, one can often observe a different CD spectrum from that of the nujol-mull method. 

I.R. characterisation of the samples is carried out using the KBr technique. U.V. spectroscopy was used for the semi-quantitative determination of the amount of intracrystalline phthallocyanines, after dissolution of the zeolite in concentrated sulfuric acid (0.1 g of catalyst in 10 ml of concentrated H2SO4 for 4 h). The iron content of the samples is determined by chemical analysis. X-ray powder diffraction is used to ensure good crystallinity of the zeolite after the synthesis and purification procedures. 

Infrared spectra were recorded on a PE-580B instrument with data station. Lattice vibration spectra were obtained using the KBr technique. Hydroxyl spectra were scanned on self-supporting wafers of the samples mounted in a vacuum cell. Spectral averaging was usually 9 times. 

Chen, J. Y. T., Micro-KBr Technique of Infrared Spectrometry, J. Assoc. 

IR spectroscopic measurements were performed in the mid and far infrared regions. For mid infrared measurements a Matson Genesis FT-IR spectrometer and the KBr technique (2 mg of sample in 200 mg KBr) were utilized. Far infrared measurements were run on a Bio-Rad-Win-IR FT-IR spectrometer in the 500-100 cm range. In this case HDPE (high density polyethylene) was the matrix material and 128 scans were collected for... 

IR spectra were recorded with a Bruker IFS 88 spectrometer using KBr technique. Observed infrared bands were interpreted using assignment presented by Ladwig [3] for VOPO4 hydrates and by Busca [6] for V0k3 04.1/2 H2O and (VO)2P 7. 

Nujol presents three major absorption bands beyond which the spectrum of the sample is exploitable. This spectrum can be supplemented by another carried out in hexachlorobutadiene, transparent in the regions where paraffin absorbs. For the KBr technique, the sample is crushed with KBr in an agate mortar. The mixture is then pressed using an hydraulic press (pressure of 5 to 8t/cm ) or manually into a transparent disc. 

For further characerlzatlon pellets prepared by the KBr-technique (zeollte KBr=li400. pressure =15 MPa) were investigated In the lattlc vibration region on a SPECORD M 60 (Carl Zeiss Jena). 

The XRD-pattems were recorded using the transmission diffractometer STADl P (Stoe) and the infrared spectra of the samples were recorded with the FTIR-spectrometer Galaxy 5020 (Mattson) using KBr technique. 

It is worthy to note that IR spectroscopy was also relatively early employed to identify and investigate framework vibrations (vide supra, cf. [112, 114] and Sect. 5.2). In these experiments, usually the so-called KBr-technique was used (cf. Sects. 2.5,4.2). Relationships between the vibration modes and, e.g., the nsi/n i ratio of the zeolite fi-amework were disclosed and discussed. 

Since the pioneering work by Flanigen et al. [ 112], many other studies of zeolite frameworks have appeared which used the IR/KBr technique, and frequently the interpretation of the obtained spectra was in line with or analogous to that given byFlanigenetal. [112] and Flanigen [ 114]. In many cases, the IR or Raman spectroscopic experiments were imdertaken in order to complement a general characterization of the molecular sieves imder study by, e.g., NIR, UV-Visible, XRD, MAS NMR spectroscopies or adsorption measurements. 

The T-O-T vibrations of cobalt-exchanged ferrierites were monitored by the FUR/KBr-technique in a work by Sobalik et al. [265] who attempted to evaluate quantitatively the intensity of the main band at 1070 cm and, thus, to determine the munber of Co + ions at cationic sites. 

Similar to Ti-containing molecular sieves, an IR band at ca. 960 cm was also reported for [Si,V]MFI structures (cf., e.g., [340] and Volume 1, Chapter 7, pages 208-209, of the present series and references therein). Thus, Hongbin Du et al. [341] observed by the FTIR/KBr technique in synthesized large pore V-contain-ing zeolite Beta a band at 960 cm" and took the appearance of this signal as an indication of vanadium incorporation into the framework to produce H-[Si,Al,V]Beta. 

Titanium siHcoaluminophosphate with MFI-structure, designated as TAPSO, was prepared by Tuel [573], and characterized, inter aha, by transmission IR spectroscopy using the KBr technique. The author found OH stretching bands at 3745, 3670,3620 and 3530 cm similar to those observed with SAPO-5. Also, a band around 970 cm was detected and related to the presence of Ti in the framework (cf. Sect. 5.2). 

We previously showed that differential FT-IR using a lyophilized KBR technique offered a powerful method for determining substitution positions on purine bases (195). The resolution is greatly enhanced and shoulders became clear bands when solution spectra taken in an attenuated total reflectance CIRCLE microcell are recorded as second derivatives. Fig. 2.54 shows regular absorbance spectra of substituted guanines together with the corresponding second-derivative spectra (378, 388). 

Solid-phase techniques have seen some limited use in the ultraviolet, visible, and near infrared. Wyman has discussed the use of the KBr technique in the ultraviolet... 

Figure 13.15 shows the spectrum of uric acid for reference and the lower curve is that of a kidney stone which is seen to be mic acid by comparison with the reference spectrum. This application of the KBr technique has been applied in clinical situations. 

---