Spectroscopy anions

T.M. Hancewicz, In J. Cross (Ed.), Molecular Spectroscopy I—Infrared and Raman Spectroscopy, Anionic Surfactants, Analytical Chemistry, Surfactant Science Series, Vol. 73, Marcel Dekker, New York, USA, 1998, p. 125. 

The exact nature of scale is best determined by FTIR or X-ray spectroscopy. Anions and the cations respectively in the water phase can be determined through methods such as atomic adsorption (for cations) and ion chromatography (for anions). Unlike microbiological and organic deposits, determining the exact chemical composition of the scale is critical to establishing the best approach for reduction of scale formation. 

Konig and Walldorf recommend determining surfactants after evaporating the sample to dryness and obtaining a 95% ethanol extract of the residue (35,36). Qualitative identification is made by TLC examination of the original extract, as well as by IR analysis. The extract is further partitioned prior to IR analysis The residue is dissolved in water, and an acid ether extract is obtained. The aqueous phase is neutralized and evaporated to dryness. The residue from both phases is analyzed by IR spectroscopy. Anionic surfactants and soap are determined by two-phase titration. Nonionics are separated by ion exchange techniques from the other components and identified by IR or TLC on silica gel impregnated with oxalic acid. PEG is separated from nonionic surfactant by partition between water and butanol, and its identity confirmed by TLC. 

The transition-state spectroscopy experiment based on negative-ion photodetachment described above is well suited to the study of the F + FI2 reaction. The experiment is carried out tln-ough measurement of the photoelectron spectrum of the anion FH,. This species is calculated to be stable with a binding energy of... 

The observation of a bend progression is particularly significant. In photoelectron spectroscopy, just as in electronic absorption or emission spectroscopy, the extent of vibrational progressions is governed by Franck-Condon factors between the initial and final states, i.e. the transition between the anion vibrational level u" and neutral level u is given by... 

Leopold D G, Ho J and Lineberger W C 1987 Photoelectron spectroscopy of mass-selected metal cluster anions. I. Cuji, n = 1 -10 J. Chem. Phys. 86 1715... 

Ding C F, Wang X B and Wang L S 1998 Photoelectron spectroscopy of doubly charged anions intramolecular Coulomb repulsion and solvent stabilization J. Phys. Chem. A 102 8633... 

Gantefor G, Meiwes-Broer K H and Lutz H O 1988 Photodetachment spectroscopy of cold aluminum cluster anions Phys. Rev. A 37 2716... 

Iseda M, Nishio T, Han S Y, Yoshida H, Terasaki A and Kondow T 1997 Electronic structure of vanadium cluster anions as studied by photoeieotron spectroscopy J. Chem. Phys. 106 2182... 

The duoroborate ion has traditionally been referred to as a noncoordinating anion. It has shown Httie tendency to form a coordinate—covalent bond with transition metals as do nitrates and sulfates. A few exceptional cases have been reported (13) in which a coordinated BF was detected by infrared or visible spectroscopy. 

Aromatic Radical Anions. Many aromatic hydrocarbons react with alkaU metals in polar aprotic solvents to form stable solutions of the corresponding radical anions as shown in equation 8 (3,20). These solutions can be analyzed by uv-visible spectroscopy and stored for further use. The unpaired electron is added to the lowest unoccupied molecular orbital of the aromatic hydrocarbon and a... 

In aqueous solution, all the sodium peroxoborates dissociate for the most part into boric acid, or its anion, and hydrogen peroxide. Peroxoborate species are also present in these solutions, depending on the pH and the concentration for the species type. The nature of these species has been extensively examined by classical physicochemical methods (13), by nmr, and by Raman spectroscopy (14—17). Both monomeric and polymeric species are usually present. There is some evidence (18) suggesting that these peroxoborates are more reactive than hydrogen peroxide alone under similar conditions. 

The sodium hydroxide is titrated with HCl. In a thermometric titration (92), the sibcate solution is treated first with hydrochloric acid to measure Na20 and then with hydrofluoric acid to determine precipitated Si02. Lower sibca concentrations are measured with the sibcomolybdate colorimetric method or instmmental techniques. X-ray fluorescence, atomic absorption and plasma emission spectroscopies, ion-selective electrodes, and ion chromatography are utilized to detect principal components as weU as trace cationic and anionic impurities. Eourier transform infrared, ft-nmr, laser Raman, and x-ray... 

There is very little published information on the UV spectra of 1,2-benzisothiazoles, though more data are available on the 2,1-isomers. The spectra are complex with as many as six maxima above 200 nm. Representative wavelengths of maxima are collected in Table 12. In all cases the most intense bands (e > 15 000) are those at short wavelengths, but all the bands indicated in the table have molar absorptivities greater than 4000, except those of 3-amino-2,l-benzisothiazole. Saccharin absorbs weakly at 350 nm and 277 nm, with intense bands below 230 nm (ethanol solvent) (82UP41700>. It exists as the anion except in acid solutions. The UV spectra of cations formed from 3-amino-2,l-benzisothiazole are discussed in (69CB1961>. Further applications of UV spectroscopy in studying tautomeric... 

In presence of polyamines the maximum of light absorption of indicated triphenylmethane dyes displaces on 10-30 nm, for azo dyes the shift of the band reaches 50-80 nm. The greatest difference of light absorption of associates and reagents is watched for BKM at pH 5,05, for BPR at pH 4,20, for CPR in an interval pH 5,05-5,45. At these pH dyes are anions, it promotes interaction with a cationic surface-active substance. The ratios between polymer and BKM, BPR, CPR are established by spectroscopy method, its equal 1 20, 1 20 and 1 30 accordingly. 

Pretreatment of the collected particulate matter may be required for chemical analysis. Pretreatment generally involves extraction of the particulate matter into a liquid. The solution may be further treated to transform the material into a form suitable for analysis. Trace metals may be determined by atomic absorption spectroscopy (AA), emission spectroscopy, polarogra-phy, and anodic stripping voltammetry. Analysis of anions is possible by colorimetric techniques and ion chromatography. Sulfate (S04 ), sulfite (SO-, ), nitrate (NO3 ), chloride Cl ), and fluoride (F ) may be determined by ion chromatography (15). 

NMR spectroscopy is ideal for detecting charged fluorinated intermediates and has been applied to the study of increasingly stable carbocation and carbanion species. Olah [164, 165] has generated stable fluorocarbocations m SbFj/SOjClF at low temperatures The relatively long-lived perfluoro-rerr-butyl anion has been prepared as both the cesium and tris(dimethylamino)sulfonium (TAS) salts by several groups [166, 167, 168], Chemical shifts of fluonnated carbocations and carbanions are listed m Table 23. 

NMR and visible spectra have established that a number of S-N anions are present in such solutions.The primary reduction products are polysulfides Sx, which dissociate to polysulfur radical anions, especially the deep blue 83 ion (/Imax 620nm). In a IM solution the major S-N anion detected by NMR spectroscopy is cycZo-[S7N] with smaller amounts of the [SSNSS] ion and a trace of [SSNS]. The formation of the acyclic anion 5.23 from the decomposition of cyclo-Sjl is well established from chemical investigations (Section 5.4.3). The acyclic anions 5.22 and 5.23 have been detected by their characteristic visible and Raman spectra. It has also been suggested that a Raman band at 858 cm and a visible absorption band at 390 nm may be attributed to the [SaN] anion formed by cleavage of a S-S bond in [SSNS]. ° However, this anion cannot be obtained as a stable species when [SsN] is treated with one equivalent of PPhs. 

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