Absorption spectra vapor phase

The ultraviolet absorption spectrum of thiazole was first determined in 1955 in ethanolic solution by Leandri et al. (172), then in 1957 by Sheinker et al. (173), and in 1967 by Coltbourne et al. (174). Albert in 1957 gave the spectrum in aqueous solution at pH 5 and in acidic solution (NHCl) (175). Nonhydroxylic solvents were employed (176, 177), and the vapor-phase spectrum was also determined (123). The results summarized in Table 1-15 are homogeneous except for the first data of Leandri (172). Both bands A and B have a red shift of about 3 nm when thiazole is dissolved in hydrocarbon solvents. This red shift of band A increases when the solvent is hydroxylic and, in the case of water, especially when the solution becomes acidic and the extinction coefficient increases simultaneously. 

Valence Vibrations. pCH and pCD. In the 3100 cm region the infrared spectrum of thiazole shows only two absorptions at 3126 and 3092 cm F with the same frequencies as the corresponding Raman lines (201-4) (Fig. I-IO and Table 1-23). In the vapor-phase spectrum of... 

The proton magnetic resonance spectrum (carbon tetrachloride) consists of a broad methine signal centered at S 2.55 and a methyl singlet at 8 1.53 superimposed upon a methylene absorption at 8 1.25-1.85. Vapor phase chromatographic analysis denoted a purity of >98%. 

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]. 

The following physico-chemical properties of the analyte(s) are important in method development considerations vapor pressure, ultraviolet (UV) absorption spectrum, solubility in water and in solvents, dissociation constant(s), n-octanol/water partition coefficient, stability vs hydrolysis and possible thermal, photo- or chemical degradation. These valuable data enable the analytical chemist to develop the most promising analytical approach, drawing from the literature and from his or her experience with related analytical problems, as exemplified below. Gas chromatography (GC) methods, for example, require a measurable vapor pressure and a certain thermal stability as the analytes move as vaporized molecules within the mobile phase. On the other hand, compounds that have a high vapor pressure will require careful extract concentration by evaporation of volatile solvents. 

One of the first applications of this chopped-beam irradiation technitriplet spectra was reported by Labhart From a knowledge of the intensity of the irradiation light, he determined the quantum yield of triplet generation to be 0.55 0.11 for outgassed solutions of 1,2-benzanthrazene in hexane at room temperature. Hunziker 32) has applied this method to the study of the gas-phase absorption spectrum of triplet naphthalene. A gas mixture of 500 torr Na, 0.3 mtorr Hg, and about 10 mtorr naphthalene was irradiated by a modulated low-pressure mercury lamp. The mercury vapor in the cell efficiently absorbed the line spectrum of the lamp and acted as a photosensitizer. The triplet state of naphthalene was formed directly through collisional deactivation of the excited mercury atoms. 

The spectrum of 1,2,3-triazole has been recorded in solution and in the vapor phase, and an analysis made of the absorption bands. The conclusion is drawn that the asymmetric (fH-) structure is present in the vapor phase and in dilute solution (although a criticism of this interpretation has appeared ). A similar conclusion is reached concerning the structure of 4-phenoxytriazole. ... 

The NH stretching band in triazole appears in the vapor phase at 3522 cm and in carbon tetrachloride at 3470 cm in the solid phase the NH absorption is a broad band at 2400-3300 cm (for 4-phenyl-triazole). The CH stretching frequency of 4- or 5-unsubstituted triazoles is at 3100-3140 cm (liquid phase).In-plane and out-of-plane deformation bands of the CH bond have also been distinguished at 1237 and 1076 cm (in the solution spectrum of 1,2,3-triazole), at 1290-1150 and 850-700 cm (for various substituted triazoles) and at 1149—1074 and 855-825 cm (for 2-aryltriazoles). ... 

Benzo[c]furan (4) exhibits a long-wave absorption band of medium intensity in the region of 340 nm. Lack of solvent dependence together with mirror relationship to the fluorescence spectrum signifies a tt-ti band a rotational analysis of the vapor phase spectrum led to an assignment as 82 <- Ap 1,3-Diaryl-substituted benzo[c]furans show a strong absorption band in the region of 415 nm in sterically hindered compounds, this... 

Electronic Spectra of d6 Metal Hexacarbonyls and Hexacyanides. A. Metal Hexacarbonyls-—The electronic spectrum of Cr(CO)6 in the vapor phase shows two intense absorption bands at 35,780 and 44,480... 

The ultraviolet absorption spectra of cyclohexanone in the vapor phase and in heptane solution appear to be identical and are situated in the same region of the spectrum as that of cyclopentanone, although more band structure is apparent in the latter instance (24). 

Fig. 6. The vapor-phase absorption spectrum of isoquinoline-d7 in the region of the lowest singlet system...

Tellurium-oxygen system comprises a wide number of phases. Tellmium monoxide TeO probably exists only in the gas phase. No evidence of its existence in the solid state has been obtained. The He(I) photoelectron spectrum of the molecular beam that has been formed by heating Te02 in vacuo indicates that TeO is the dominant species in the vapor phase.Studies of the absorption and emission spectra of TeO(g) have yielded the bond dissosiation energy of263.2kJmoU. The Te=0 bond length of 1.828 A. is estimated from the rotational fine structme of the electronic absorption spectrum. 

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