Ethanal infrared absorptions

Brown, A.C., Canosa-Mas, C.E., Parr, A.D., Wayne, R.P (1990) Laboratory studies of some halogenated ethanes and ethers measurements of rates of reaction with OH and of infrared absorption cross-sections. Atmos. Environ. 24A, 2499-2511. 

Figure 4 illustrates the infrared spectrum for a sample of PPE. The absorptions of the peaks at 3.4, 6.9 and 7.3 pm were assigned to C-H stretch and C-H bending frequencies in CH2 and CH3 (33). These absorptions are proportional to the surface density of deposited ethane (16). However, the absorptions at photons near 10 pm are attributable to OH deformations and CO stretchings of alcoholic groups and vibrations of alkyl ketones (22). They also indicate the existence of branches in unsaturated chain (33). 

In an early study of ethane adsorbed on Pt supported on porous silica glass, Clark (77) found no infrared bands on initial adsorption at room temperature, 453, or 513 K, but on hydrogenation observed absorptions near 2935 and 2870 cm1, which could be attributed to surface alkyl species. 

An infrared study of the interaction of ethane with a Pd/Al203 catalyst did not reveal any absorption bands of adsorbed species at (seemingly) 373 K but strong bands indicative of oxygenated (carboxylate) surface species were obtained at temperatures between 373 and 478 K when ethane plus air was in contact with the catalyst (733). 

Very few experiments have been performed on vibrational dynamics in supercritical fluids (47). A few spectral line experiments, both Raman and infrared, have been conducted (48-58). While some studies show nothing unique occurring near the critical point (48,51,53), other work finds anomalous behavior, such as significant line broadening in the vicinity of the critical point (52,54-60). Troe and coworkers examined the excited electronic state vibrational relaxation of azulene in supercritical ethane and propane (61-64). Relaxation rates of azulene in propane along a near-critical isotherm show the three-region dependence on density, as does the shift in the electronic absorption frequency. Their relaxation experiments in supercritical carbon dioxide, xenon, and ethane were done farther from the critical point, and the three-region behavior was not observed. The measured density dependence of vibrational relaxation in these fluids was... 

In this chapter, we describe the density- and temperature-dependent behavior of the vibrational lifetime (TO of the asymmetric CO stretching mode of W(CO)6( 2000 cm-1) in supercritical ethane, fluoroform, and carbon dioxide (C02). The studies are performed from low density (well below the critical density) to high density (well above the critical density) at two temperatures one close to the critical temperature and one significantly above the critical temperature (68-70). In addition, experimental results on the temperature dependence of Ti at fixed density are presented. Ti is measured using infrared (IR) pump-probe experiments. The vibrational absorption line positions as a function of density are also reported in the three solvents (68,70) at the two temperatures. 

The magnitudes of the barriers to rotation of many small organic molecules have been measured. The experimental techniques used to study rotational processes include microwave spectroscopy, electron diffraction, ultrasonic absorption, and infrared spectroscopy. Some representative barriers are listed in Table 2.1. As with ethane, the barriers in methylamine and methanol appear to be dominated by hyperconjugative stabilization of the anti conformation. The barrier decreases (2.9 2.0 1.1) in proportion to the number of anti H-H arrangements (3 2 1). (See Topic 1.1 for further discussion.) ... 

Multiphoton infrared excitation of the sulfoxide stretching chromophore (ca. 1100 cm ) of DMSO also leads to production of CH3 and SO in their respective electronic ground states [120]. The direct formation of ethane was once again eliminated, this time by product analysis from double label experiments with DMSO and its Dg isotopomer. Time resolved detection of IR absorptions was used to analyze products. Though, once again, CHjSO- was not directly observed, these authors favor a stepwise decomposition because of a nonthermal rotational level distribution of the SO fragment. 

Frantz et al. (1966) have isolated a sterol from the skin of rats treated with triparanol (l-[p-( S-diethylaminoethoxy)phenyl]-l-(p-tolyl)-2-(p-chlorophenyl)ethan-ol). Infrared and NMR spectroscopy were used to characterize the new compound. The close similarity of the spectra of A -cholesten-3p-ol and A -cholestadien-3) -ol was proof of the presence of the bond and of the identity of the ring system in the two compounds. The diminution in the absorption at 1368 cm", prominent in cholesterol, A -cholesten-3j8-ol, and other sterols with a saturated side chain, was evidence for the absence of the isopropyl group and compatible with the presence of a or A bond. The absence of a band at 887 cm" eliminated the latter possi-... 

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