Potassium bromide matrix

The CO radical in the latter case was generated by the radiolysis of sodium formate in potassium bromide matrix The broadening of the spectrum (full width at half maximum 40 cm ) is consistent with the model of a radical adsorbed on the electrode surface. 

Examine the spectra of the reaction products you have obtained, in a potassium bromide matrix. Discuss the similarities and differences of the experimentally derived spectral data to the reference spectra (Figs. 6.16-6.18). 

Polycrystalline or powdered samples can be prepared as a suspension in mineral oil (Nujol mull), as a potassium bromide disk (pellet), or as thin films deposited on infrared-transparent substrates. The potassium bromide pellet is the most common way of preparing powder samples in this method a small amount, usually 1 mg, of finely-ground solid sample is mixed with powdered potassium bromide, usually 300 mg. and then pressed in an evacuated die under high pressure. The resulting disks are transparent and yield excellent spectra. The only infrared absorption in the potassium bromide matrix is due to small amounts of adsorbed water, which can. however, be confused with OH-containing impurities in the sam-... 

Hartman KO, Hisatsune IC (1967) Kinetics of oxalate ion pyrolysis in a potassium bromide matrix. J Phys Chem 71 392-396... 

Vibrational spectra can be observed by a variety of techniques, namely, infrared, Raman, and photoelectron spectroscopy and inelastic neutron scattering. Of these, for organic molecular solids, the first two are the ones in genraal use, in particular, infrared spectroscopy. Usually, spectra of sohd samples are obsawed either from suspensions in Nujol (a long-chain aliphatic molecule) or from pressed disks made from a potassium bromide matrix. The former technique, although used extensively by the organic chemist, is of very limited use to the sohd state chemist, because of the possibility... 

Dispersed in an infrared transparent powder. Pellets are made with I to 2% by weight of the sample, usually in dry potassium bromide. A pellet of approximately 300 mg is prepared in a mould called a matrix using a laboratory press. This method produces pellets 1 to 2 mm thick for a diameter of approximately 13 mm. This technique can be used for quantitative studies but the spectra may sometimes differ ftom those obtained via dispersion in a liquid. This is because, under the effect of the high pressure to which the powder is subjected, the solid may undergo certain modifications. 

Clearly, both vibrational and UV-visible spectroscopy also play an important role in materials chemistry, and are well described in other texts. The principles involved in carrying out these experiments on solids rather than in solution are similar, but often experimental methods vary. For example, an IR spectrum of a zeolite would be carried out by dispersing the solid in a matrix of potassium bromide and pressing into a disk, rather than in solution. Typically, a UV-visible spectrum of a solid would be carried out in diffuse reflectance mode, where the solid is dispersed in a white matrix (such as barium carbonate) and the UV light is reflected off the surface rather than passing through a solution. 

Ataman, O. Y. and Mark, H. B., Jr., Ion exchange between ammonium zeolite and the supporting matrix in potassium bromide pellets, Analytical Letters 9(12), 1135-1141 (1976). 

The lower limit is normally defined by the sampling method or matrix or by the optics of the instrument. In the latter case, the standard potassium bromide (KBr) beam splitter substrate of a Fourier transform IR (FTIR) instrument provides an optical cutoff at approximately 400 cm Fundamental vibrations do extend below this cutoff, and these are normally associated with either low-energy lattice vibrations or the vibrations of chemical bonds involving the heavier elements. The region below 400 an (this limit is subjective) is referred to as the far infrared. 

Is the polymer matrix as claimed Infra-red analysis is a good technique for this determination. IR spectra can be obtained quickly with minimum sample preparation. Liquids and films can be run directly. The dust from filing a solid sample can be ground with potassium bromide (KBr) and a pellet pressed for analysis. Is the additive readily apparent in the spectrum ... 

The solid pigment sample can be analyzed directly using attenuated total reflectance (ATR) devices or by mixing with non-IR absorbing salts such as potassium bromide (KBr) or sodium chloride (NaCl). Normally the pigment sample is dried prior to analysis and the FT-IR spectrum is recorded. The sample preparation is minimal except when quantitative analysis is needed or when the sample matrix is quite complex or the pigment is present at low concentrations. 

Any solid, liquid, or gas sample can be analyzed using FTIR spectroscopy. The most common method to prepare solid samples involves use of a matrix to disperse the ground sample. The matrix can be a liquid (mineral oil) or solid (potassium bromide). For a liquid matrix, the paste of the ground sample and the liquid is spread between two IR transparent windows. For a solid matrix, a mixture of ground sample and potassium bromide (KBr) is pressed under high pressure ( 80 MPa) for a few minutes. Reciystalhzation of KBr results in a clear disk, which can be inserted into the optical beam with a special sample holder. Liquids are analyzed as thin films in a cell with two IR transparent windows. A Teflon spacer is generally used to produce a film of the desired thickness (Reh, 2001). 

Solids. There are several methods for determining infrared spectra for solids. One method of choice has been to mix a finely ground sample with powdered potassium bromide and press the mixture under high pressure. Under pressure, the potassium bromide melts and seals the sample into a matrix. The resulting KBr pellet is inserted in the instrument. If a good pellet is prepared, the spectrum obtained will have no interfering bands since potassium bromide is transparent down to 400 cm . ... 

Infrared spectral studies were done utilizing a Mattson Instruments Galaxy 4020 FTIR employing potassium bromide pellets. All spectra were recorded at an instrument resolution of 4 cm using 32 scans. Mass spectra were obtained utihz-ing a HP Mdl. G2025A MALDI-TOF (matrix-assisted laser ionization time-of-flight) mass spectrophotometer. 

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