Infrared spectrum absorption process

All attempts to isolate efficient process giving a white solid polymer which appears to have repeating keteneimine units. This assignment is consistent with the very strong absorption at 2140 cm.-1 in the infrared spectrum. ... 

We note that the formalism presented here plays a major role in infrared spectroscopy. The process that gives rise to a fundamental line in the infrared spectrum of a molecule is the absorption of a photon whose frequency corresponds to that of one of the normal modes, and the simultaneous transition of this mode from the ground state (n = 0) to the first excited state. 

The intense absorption of water over most of the infrared spectrum restricts the regions where aqueous solutions of carbohydrates can be usefully studied. Absorbance subtraction makes it possible to eliminate water absorbance and magnify the remaining spectral features to the limit of the signal-to-noise ratio. Many other data-processing techniques, such as the ratio method,4 the least-squares refinement,5 and factor analysis,6 should be of benefit in the study of carbohydrate mixtures. 

For fundamental physical reasons, the attenuation function for any process must vanish as to - °°. This expectation is borne out by far-infrared measurements of ct(u>) for a variety of molecular systems exhibiting a relaxation-type absorption in the microwave and millimeter-wave region (17-23). While H2O as a solute in nonhydrogenbonding solvents also shows this behavior (35), the millimeter-wave and far-infrared spectrum of 0(2.) is complicated by contributions to a (10) due to intermolecular vibrations involving a cluster of H2O molecules (libration and translation), in addition to the high-frequency tail of the relaxation absorption. A heuristic treatment of the general problem (30) makes the relaxation time,... 

NIR (near infra red) spectroscopy — Besides optical absorption in the UV-Vis region of the electromagnetic spectrum, absorption in the near infrared region can be employed to study electrochemical processes. This part of the electromagnetic spec-... 

The complex is obtained as deep olive-green platelike crystals, m.p. 142° (decomposes). The solid compound decomposes slowly on exposure to the atmosphere the process is greatly accelerated if the material is finely divided. The preparation of samples for physical measurements must be carried out in a nitrogen atmosphere. The complex forms very air-sensitive solutions in 1-butanol or nitromethane. The infrared spectrum exhibits characteristic ionic perchlorate absorptions at 1100 and 625 cm, and there are strong ligand bands at 1625, 1400, 575, 500, and 380 cm-i. 

The authors found that the in situ electrochemical potentiokinetic reactivation (EPR) data obtained for the monocation I" " showed that the two Mn centers had identical spin densities, and hence the cation showed delocalized mixed valence the near-infrared spectrum supported this postulate. If such a delocalized system existed on the infrared timescale, then two bands would be expected in the carbonyl region of the infrared spectrum of 1+ at frequencies intermediate between those of the Mn(I)/Mn(I) neutral complex, (1861 and 1934 cm ), and those of the fully oxidized Mn(II)/Mn(II) species, which were predicted to be ca. 1966 and 2048 cm on the basis of the bands observed for CpMn(II)(CO)2PPh3 +, (Cp = cyclopentadienyl). In contrast, four intense CO absorptions were observed near 1888, 1931, 1952, and 2003 cm , which were typical of the trapped valent Mn(II)/Mn(I) species. The variation in the response obtained on the EPR timescale, ca. 10 s, to that observed on the infrared timescale, ca. 10 s, was taken by the authors as implying a time-dependent localization process. 

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