Sulfur dioxide absorption spectrum

Four IR absorption bands have been identified in the spectrum of the hydroxysulfonyl radical (HOSO 2) which has been obtained by the reaction of hydroxyl radicals with sulfur dioxide in argon matrix at 11 K16. The observed bands at 3539.9 and 759.5 cm 1 have been assigned to O—H and S—OH stretching modes while the bands at 1309.2 and 1097.3 cm-1 have been assigned to the asymmetric and symmetric stretching modes of the double bonded S02 moiety. These data are consistent with the theoretical prediction on the geometry of the hydroxysulfonyl radical12. 

A mixture of sulfur dioxide. S02. and sulfur vapor, at low pressure and with an electric discharge, forms sulfnr monoxide, SO Its presence is shown from its absorption spectrum, but upon separation it dispropor-tionates at once to sulfur and S02. Sulfur sesquioxide. S2Ojt, is formed by reaction of powdered sulfur with anhydrous SO3 S20 also dispropor-tionates (at 20°C in nitrogen) to sulfur and S02, Sulfur dioxide, S02, is... 

OP-UV spectrometry can be used to measure vapors or gases that have weak absorption characteristics, and therefore, low sensitivities in the IR spectrum. These include such compounds as nitrogen oxides, formaldehyde, ozone, sulfur dioxide, benzene, toluene, and xylenes, and also homonuclear diatomic molecules, such as chlorine. The compounds that can be determined by UV are much fewer (see Table 3.43) than those that are absorbing in the IR spectra. 

Cobalt is determined spectrophotometrically using the absorption spectrum of CoCU " in 10 M hydrochloric acid. Iodine is determined by precipitation of silver iodide after reduction of the complex with sulfur dioxide. Titratable H" " is determined by a potentiometric pH titration. AnaL Calcd. for H3[Co4l3024Hi2] 3H20 Co, 22.04 I, 35.59 titratable H+, 0.282 ratio CorlrH" " = 1 0.75 0.75. Found Co, 22.0 I, 35.45 titratable H", 0.285 ratio Co.T H = 1 0.75 0.75. 

Other studies on the chemistry and spectroscopy of pure SO2 cast further light on the question of the possible existence of an isomer of the form SOO. Norrish and Oldershaw flash-photolyzed sulfur dioxide and found that as the SO2 spectrum disappeared, a continuous absorption in the far uv appeared and faded slowly as the SO2 reappeared. There was little net chemical change as a result of the flash. They agreed that the intermediate spectrum might be due to an isomer of sulfur dioxide. However, both Herman et al., and Gaydon et al -, argued that the new spectrum could be due to heated SO2 alone, and no new species need be... 

The photooxidation of CS2 and COS has also been examined in flash photolysis studies. The spectra of a number of sulfur oxides have been detected. Both SO2 and SO have been definitely identified A system of absorption bands appearing between 2500 and 2400 A. have been assigned to the sulfur monoxide molecule, S2O, on the basis of mass spectrometric evidence. A transient spectrum observed in the wavelength region, 1840-1740 A., has been tentatively assigned to a short-lived isomeric form of sulfur dioxide, the structure of which may be SOO, sulfur superoxide. The probable precursor of all these species is the sulfur monoxide which arises from the reaction of atomic sulfur with O2. The overall reaction is complex a number of possible steps have been postulated to account for the intermediates, SO and SOO, as well as for the final products S2O and SO2. With triplet sulfur atom, the most likely reaction to produce SO is S( P) -H Ojf S,-) S0(32 ) -I- 0(V) (43)... 

Both technological and atmospheric radiation are mostly associated with water vapor and carbon dioxide, which are significant emitters and absorbers. Other examples of gases of significant emission and absorption properties are carbon monoxide, sulfur dioxide, ammonia, and hydrogen chloride. In general, radiation occurs over a number of discrete bands of the electromagnetic spectrum (recall Fig. 8.2). However,... 

Interferences caused by selective absorption by other molecules are minimized by judicious control of the thermal conditions at the lamp. The character and amplitude of the lamp s emission spectrum depend on the temperatiu-e. Interferences by sulfur dioxide and hydrocarbons... 

The adhesion of RFL-coated tire cords to rubber can be adversely affected if the dipped cords are exposed to ozone, UV light, nitrogen oxides, sulfur dioxide, or air before vulcanization into rubber. lyengar proposed that ozone exposure of RFL reduces adhesion because ozone attacks the double bonds of the butadiene component of the rubber latex and impairs its cocuring with the solid rubber compound. Infrared studies by Solomon reinforced this argument. When typical RFL films were exposed to ozone, the IR spectrum showed an increase in IR absorption at 1720 cm corresponding to an increase in the carbonyl content in the exposed film. An RFL film with no ozone exposure did not show this absorption at 1720 cm The increased carbonyl content is due to the reaction of some double bonds in the rubber with ozone and therefore, would leave fewer unsaturation sites for rubber crosslinking and adhesion. 

Signatures of water vapor are scattered throughout the terrestrial spectrum shown in Fig. 6.2.1 below 500 cm and between 1300 cm and 2000 cm the atmosphere is nearly opaque at low latitudes. Water vapor features also appear in the spectra of Mars and Venus, but are reduced in strength. The Venus spectrum also shows the broad absorption features of liquid sulfuric acid (H2SO4) clouds near 900 cm (Fig. 6.2.2) and possibly of sulfur dioxide (SO2) gas near 1360 cm (Fig. 6.2.3). In the Earth spectrum the strong vs-band of ozone (O3) at 1042 cm and the V4-band of methane (CH4) at 1306 cm can easily be identified. 

Fig. 6.5.1 Voyager 1 IRIS lo spectrum over the hot spot Loki Patera. The strong 1361 cm V3-band of sulfur dioxide (SO2) is seen in absorption (Pearl et al 1979). Synthetic spectra for two SO2 abundances are also shown for comparison.

Although many crystalline sulfur dioxide solvates of salts have been prepared (66), there appears to be no geometrical structural information on any of these substances. Spectroscopic evidence, however, indicates that their bonding is of the chai transfer variety. Thus alkali, ammonium, and alkaline earth iodides perturb the infrared spectrum of SO in acetonitrile to an extent which is essentially independent of the cation and in a fashion which is consistent with charge transfer complex formation (67). The absence of such perturbation by KBr and KCl is, presumably, due to their association constants being too low to permit observation of the infrared absorption spectra of the complexes. Spectroscopic evidence of complexation of SO with bromide and chloride ions has been obtained in the author s laboratory, however (68). In dilute (ca. solutions of SO in... 

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