Spectroscopic examination

The existence of neon (Greek neos, new) was predicted, as was the existence of heavier members of the group. In 1898 krypton (Greek kTyptos, hidden) was discovered by spectroscopic examination of the residue from a sample of Hquid air. Neon was discovered in the same year. A month later, xenon (Greek xenos, strange) was isolated from the residue left after distillation of krypton. 

Spectroscopic examination of light scattered from a monochromatic probe beam reveals the expected Rayleigh, Mie, and/or Tyndall elastic scattering at unchanged frequency, and other weak frequencies arising from the Raman effect. Both types of scattering have appHcations to analysis. 

Oxirene is probably a true intermediate, but is separated from ketene by only a very low barrier. Since its instability results from unimolecular isomerization rather than from attack of other molecules, the only viable current technique for its direct observation seems to be generation and spectroscopic examination in an inert matrix at temperatures near absolute zero. 

AN X-RAY PHOTOELECTRON SPECTROSCOPIC EXAMINATION OF PHOSPHORUS CONTAINING MATERIALS OVERVIEW ON METHODS ADVANCES AND ABILITIES... 

Benz[/]isoindole 10 exists, on the basis of spectroscopic examination, predominantly in the benzenoid tautomeric form 10b, although the formation of the Diels-Alder adduct with N-phenylmaleimide suggests the presence of a small amount of the o-quinoid tautomer 10a (78JOC4469). 

Accommodation of metal atoms of widely differing ionic radii into the same overall structure creates interesting possibilities for the doping of metal ions into a common matrix for spectroscopic examination under nearly constant crystal field effects. 

Alloy samples weighing either 100 or 25 g. were prepared by melting weighed amounts of lead and thallium together. The c. p. granular test lead, free from silver, gold and bismuth (Fisher Scientific Company), was indicated by spectroscopic examination to contain approximately 0-005 % iron, 0-001 % thallium and 0-001 % copper. The thallium used was supplied by the Varlacoid Company. Spectroscopic examination showed the presence of approximately 0-01 % lead, 0-005 % iron, and 0-001 % copper. 

There are in-line LC/spectroscopic systems available, but in most cases it is easier to carry out a semi-preparative separation, collect the material and carry out the spectroscopic examination off-line. However, for routine quality control analyses, where the sample... 

Different samples of chlorinated camphene containing from 62 to 72% of chlorine all give the same infrared spectra. However, the toxicity to flies reaches a maximum at a chlorine content of 67 to 69% and drops off rapidly below 60% and above 72%. From the results of both the infrared spectroscopic examination and the fly-toxicity tests given below, it is concluded that the organic-chlorine compound in the fat was essentially unchanged toxaphene. 

Acknowledgment is made of assistance in the chemical work by A. C. Hazen, H. D. Mann, and P. E. Hubanks. The infrared spectroscopic examination was made by W. C. Kenyon, Hercules Powder Company, Wilmington, Del. 

Fourier transform infrared spectroscopic examination of these polymers also supports this conclusion. As can be observed in Figure 6, a peak occurring at 2086 cm->l is seen in all the copolysilanes. This absorbance has been assigned to a Si-H stretching absorption (15). Such a moiety is expected if silyl radical abstraction of a hydrogen occurs. Examination of the infrared spectra for a Si-CHo-Si vibrational peak which should be located between 1000 and 1100 cm-1 is inconclusive due to the presence of a multitude of absorbances in this region. 

There are several variations on the theme of instrument set up, which have been used in an attempt to overcome the shortcomings inherent in the concept. For example, as an alternative to the stop-flow method, the various fractions can be collected into sample loops (small loops of capillary tubing) which can then be flushed into the flow cell and studied at leisure. After spectroscopic examination, each sample can then be returned to its loop and the next pumped in. Fractions suffer dilution in this way but this approach would seem to offer an advantage over stop-flow in that at least the chromatography is not compromised by diffusion on the column. 

A detailed spectroscopic examination should settle the question of whether the ion has the open or the cyclic structure. In general halo-chromic salts lose their color when a covalent bond is established to the central carbon atom, but the bromonium ion might resemble the carbonium ion. Compounds of similar color but which are certainly not cyclic halonium ions are also known ... 

Ti decays to 51V by the emission of 3 particles and y-rays. A spectroscopic examination gave the following energies for the radiations. 

S, 20R)-Velbanamine (160, Cl9H26N20, (M+- 298), kmax 287 nm) was isolated from leaves and twigs of T. eglandulosa (105). The minute amounts of material precluded spectroscopic examination. The structure and stereochemistry... 

Wentrup and co-workers also studied the flash vacuum pyrolysis of isopropylidene (monosubstituted amino)methylenemalonates (84JOC-2772). The pyrolysis of isopropylidene phenylaminomethylenemalonates (1223) between 400 and 600°C under a pressure of 10 5-10 3 torr afforded 4-hydroxyquinolines (1226) in 57-66% yields. The intermediates (1224 and 1225) of the pyrolysis of isopropylidene phenylaminomethylenemalonates (1223) could be isolated at - 196°C on KBr or BaF2 windows in a special apparatus allowing direct IR spectroscopic examination of the pyrolysates... 

Terbium - the atomic number is 65 and the chemical symbol is Tb. The name derives from the village of Ytterby in Sweden, where the mineral ytterbite (the source of terbium) was first found. It was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1843 in an yttrium salt, which he resolved into three elements. He called one yttrium, a rose colored salt he called terbium and a deep yellow peroxide he called erbium. The chemist Berlin detected only two earths in yttrium, i.e., yttrium and the rose colored oxide he called erbium. In 1862, the Swiss chemist Marc Delafontaine reexamined yttrium and found the yellow peroxide. Since the name erbium had now been assigned to the rose colored oxide, he initially called the element mosandrum (after Mosander) but he later reintroduced the name terbium for the yellow peroxide. Thus the original names given to erbium and terbium samples are now switched. Since Bunsen spectroscopically examined Mosander s erbium (now terbium) sample and declared that it was a mixture, the question of who actually discovered terbium, Mosander or Delafontaine remains unresolved to this day. 

The group of Stein reported on spectroscopic examinations on patients suffering from CGL. These patients also showed a single methylene peak of IMCL due to the lack of adipose tissue (i.e., EMCL in the musculature). Spectra obtained from patients with AGL or CGL confirm the earlier statements concerning the possibility of distinguishing IMCL and EMCL by NMR spectroscopy. 

The existence of this element was predicted by Mendeleev as a missing link between aluminum and indium during his periodic classification of elements. Mendeleev termed it ekaaluminum. The element was discovered in 1875 by French chemist Lecoq de Boisbaudran while he was carrying out spectroscopic examination of emission lines from Pyrenean zinc blende concentrates. Boisbaudran named this new element gallium, after Gallia, the Latin word for his native France. In the same year, Boisbaudran also separated gaUium by electrolysis. 

Both compounds crystallize with the cadmium diiodide structure (space group P3ml) as previously reported on polycrystalline samples.3 For platinum disulfide, ao = 3.542(1) A and c0 = 5.043(1) A, and for platinum ditelluride, a0 = 4.023(1) A and c0 = 5.220(3) A. Direct chemical analysis for the component elements was not carried out. Instead, precision density and unit-cell determinations were performed to characterize the samples. The densities of both compounds as determined by a hydrostatic technique with heptadecafluorodeca-hydro-l-(trifluoromethyl)naphthalene as the density fluid4 indicated that they are slightly deficient in platinum. For platinum disulfide, = 7.86 g/cm3 and Pmeas = 7.7(1) gm/cm3, and for platinum ditelluride, p = 10.2 gm/cm3 and Pmeas = 9.8(1) gm/cm3. In a typical experiment an emission spectrum of the platinum disulfide showed that phosphorus was present in less than 5 ppm. A mass spectroscopic examination of the platinum ditelluride revealed a small doping by sulfur (less than 0.4%) and traces of chlorine and phosphorus (less than 100 ppm). 

In 1863 Reich began a search for thallium in some Freiberg zinc ores from the Himmelsfurst mine consisting mainly of arsenical pyrites, blende, lead glance, silica, manganese, copper, and small amounts of tin and cadmium (19, 43). After roasting the blende to remove most of the sulfur and arsenic, he decomposed it with hydrochloric acid (47). When Clemens Winkler, who was then a metallurgist in the Saxon smalt works, visited Professor Reich in 1863, the latter showed him a straw-yellow precipitate and said, This is the sulfide of a new element (52). Because of his colorblindness, however, Reich entrusted the spectroscopic examination to his assistant, Richter. 

After the Curies, with the assistance of M. G. Bemont, had carried out many laborious fractionations of barium chloride, they found that the most insoluble fractions were the most radioactive. In the course of her experiments Mme. Curie had learned that radioactivity is an atomic property depending solely on the quantity of active element present." For this reason the presence of another active element was suspected, and the radioactive barium chloride was therefore submitted to M. Demarcay for spectroscopic examination. He detected a new line in the ultraviolet region of the spectrum, and certain other lines, all of which were most distinct in the most radioactive preparations, and, as fractionation proceeded, the barium lines became fainter and fainter (23, 28, 52). 

Another consequence of placing the electrode in a vacuum to study it is the removal of the solvent molecules. Thus, one may pose the following question Are the results of spectroscopic examinations of the electrode surface in vacuo (no solvent present) relevant to the study of the electrochemical interfacial region in which the solvent plays a strong role ... 

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