UV absorption spectrum

C3Hj C(HS. 03, liq, bp 70° at 0.5 mm, d 1.1361 at 20°, d 1-5132 at 20°. Can be prepd by ozonization of allylbenzene using the method of Harries (Ref 1 for oconization of org compds. A detailed description of its prepn is given by Ryffel(Ref 3). Briner et al (Ref 4) detd the following props of allylbenzeneozonide soly in benz, Raman spectra, UV absorption spectra, dielectric constants and dipole moments Note According to Dr H. Walter of PicArs this ozonide is an explosive... 

UV-Vis Spectra UV absorption of the molecule takes place and the molecules were promoted from the ground state to an excited state. Each electron vibrates and rotates to each other. 

Computed optical properties tend not to be extremely accurate for polymers. The optical absorption spectra (UV/VIS) must be computed from semiempiri-cal or ah initio calculations. Vibrational spectra (IR) can be computed with some molecular mechanics or orbital-based methods. The refractive index is most often calculated from a group additivity technique, with a correction for density. 

Bromine Pentafluoride. Bromine pentafluoride is a colorless Hquid having the molecular stmeture of a tetragonal pyramid (5). The index of refraction is 1.3529 (33). Infrared spectra (13,34), the uv-absorption spectmm (35), and vapor pressure data (11) are all available. 

Chlorine Pentafluoride. Chlorine pentafluoride is a colorless gas at room temperature. The ir and Raman spectra of the Hquid and gas phase have been studied (34,39). The uv absorption spectmm (45) and vapor pressure data may be found in the Hterature (18). 

Pteridine pAT, max UV absorption spectra loge pH Solubility 20 °C in H2O 100 °C Melting point (°C)... 

As a class the penicillins do not have a characteristic UV absorption spectrum. UV spectra did, however, play an important role in the structure elucidation of some of the penicillin degradation products during the early structure studies (B-49MI51104). 

The triarylmethyl cations are particularly stable because of the conjugation with the aryl groups, which delocalizes the positive charge. Because of their stability and ease of generation, the triarylmethyl cations have been the subject of studies aimed at determining the effect of substituents on carbocation stability. Many of these studies used the characteristic UV absorption spectra of the cations to determine their concentration. In acidic solution, equilibrium is established between triarylearbinols and the corresponding carbocations. 

Figure 13.37 shows the UV spectrum of the conjugated diene cis,trans-, 3-cyc o-octadiene, measured in ethanol as the solvent. As is typical of most UV spectra, the absorption is rather broad and is often spoken of as a band rather than a peak. The wavelength at an absorption maximum is refened to as the X ax of the band. There is only one band in the UV spectrum of 1,3-cyclooctadiene its X ax is 230 ran. In addition to UV-VIS bands are characterized by their- absorbance (A), which is a measure of how much of the radiation that passes through the sfflnple is absorbed. To correct for concentration and path length effects, absorbance is converted to molar absorptivity (e) by dividing it by the concentration c in moles per liter and the path length I in centimeters. 

The UV absorption spectra of most alkynylpyrazoles are quite similar to those of the corresponding pyrazoles. In general, they show a shift toward the visible [see (76T1293 98JCS(P1)3233)]. The UV spectra and nonlinear optical properties have been reported for 4-(4-methoxyphenylethynyl)-l-(4-nitrophenyl)-l/7-pyrazole and related compounds (94MI29). 

Ultraviolet spectra of heteropyrans have been used mainly for characterization purposes. No theoretical calculations of the spectral patterns have yet been done. Typical UV absorption characteristics of some thiopyrans and teluropyrans are collected in Table IX. Analogous insight into the UV absorption of selenopyrans is still lacking. 

Equilibrium constants for complex formation (A") have been measured for many donor-acceptor pairs. Donor-acceptor interaction can lead to formation of highly colored charge-transfer complexes and the appearance of new absorption bands in the UV-visible spectrum may be observed. More often spectroscopic evidence for complex formation takes the font) of small chemical shift differences in NMR spectra or shifts in the positions of the UV absorption maxima. In analyzing these systems it is important to take into account that some solvents might also interact with donor or acceptor monomers. 

Optical Spectral Properties. Mullen Orloff (Ref 100) give the uv absorption spectra of PETN in MeCN soin from 1825 to 3900A. 

The UV absorption spectra of sodium nitrite in aqueous solutions of sulfuric and perchloric acids were recorded by Seel and Winkler (1960) and by Bayliss et al. (1963). The absorption band at 250 nm is due either to the nitrosoacidium ion or to the nitrosyl ion. From the absorbancy of this band the equilibrium concentrations of HNO2 and NO or H20 —NO were calculated over the acid concentration ranges 0-100% H2S04 (by weight) and 0-72% HC104 (by weight). For both solvent systems the concentrations determined for the two (or three) equilibrium species correlate with the acidity function HR. This acidity function is defined for protonation-dehydration processes, and it is usually measured using triarylcarbinol indicators in the equilibrium shown in Scheme 3-15 (see Deno et al., 1955 Cox and Yates, 1983). 

To confirm these phenomena the UV absorption spectra of lithium polyisoprene of high and of low molecular weights dissolved in cyclohexane were re-examined over... 

Emission Spectra. The excited states of quinoxaline and several derivatives have been studied by means of their UV absorption and emission spectra. ... 

The metal-atom reactions of Cu (98), Ag (134), and Au (135) with O provided interesting results, especially when these were compared with the results from the nickel triad (137). As shown by standard matrix-techniques, Ag forms two O2 complexes that are best formulated as Ag 02 and Ag+Oj, based on the absence of visible absorptions and the similarity of the IR spectra to those of Cs" 02 and Cs Oj (3a,b). The UV absorptions for Ag(02) and AgiOJ, at 275 and 290 nm, respectively, could be associated with the O2 and O4 anions. The shifts in the IR spectra on going from Ag(02) to Ag(04) also argue against an (02)Ag(02) formulation for the latter complex, being in the opposite sense to those observed for Pd(02)ian[Pg.139]

Raman spectra of S2 in its triplet ground state have been recorded both in sulfur vapor and after matrix isolation using various noble gases. The stretching mode was observed at 715 cm in the gas phase [46], and at 716 cm in an argon matrix [71]. From UV absorption and fluorescence spectra of sulfur vapor the harmonic fundamental mode of the S2 ground state was derived as t e = 726 cm . The value corrected for anharmonicity is 720 cm [26, 27]. Earlier reports on the infrared absorption spectrum of 2 in matrix isolated sulfur vapor [72] are in error the observed bands at 660, 668 and 680 cm are due to S4 [17] and other species [73]. 

Platz J, OJ Nielsen, J Sehested, TJ Wallington (1995) Atmospheric chemistry of l,Ll-trichloroethane UV absorption spectra and self-reaction kinetics of CCljCHj and CCI3CH2O2 radicals, kinetics of the reactions of the CCljCHjOj radical with NO and NOj, and the fate of alkoxy radical CCI3CH2O. J Phys Chem 99 6570-6579. 

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