Iodine spectrum

Figure 10. Experimental CIS spectra of the 6 s (y = K = 4, + l) - 62 1 (upper trace) transition and the 6lb2( b = 0), (J = K = 4, +1) - 6262(1 = 0) transition (lower trace) in ben2ene-Ar (C H6 -Ar). Four dips in each spectrum ate shown indicating single rovibrational transitions with different Hoenl London factors. The iodine spectrum on top of each spectrum was synchronously recorded for absolute frequency calibration.

The glucosidase activity alone was measured by 14C-glucose incorporation into polymer (16) and the transferase activity alone was measured by the change in the iodine spectrum of amylopectin (20). 

Like the lecithins (see Fig. 4), lipids appear to behave as electron donors [1]. With I2, Rosenberg et al. [132,133] observed that lecithin yielded 2 1 iodine complexes with the appearance of the triodide spectrum, and a decrease of the iodine spectrum, similar to the changes caused by amino acids [134]. 

Fig. 23.—Absorption (--) and ORD spectra of the amylose-iodine spectrum. (Reprinted...

Figure B2.5.12 shows the energy-level scheme of the fine structure and hyperfme structure levels of iodine. The corresponding absorption spectrum shows six sharp hyperfme structure transitions. The experimental resolution is sufficient to detennine the Doppler line shape associated with the velocity distribution of the I atoms produced in the reaction. In this way, one can detennine either the temperature in an oven—as shown in Figure B2.5.12 —or the primary translational energy distribution of I atoms produced in photolysis, equation B2.5.35.

It turns out that the CSP approximation dominates the full wavefunction, and is therefore almost exact till t 80 fs. This timescale is already very useful The first Rs 20 fs are sufficient to determine the photoadsorption lineshape and, as turns out, the first 80 fs are sufficient to determine the Resonance Raman spectrum of the system. Simple CSP is almost exact for these properties. As Fig. 3 shows, for later times the accuracy of the CSP decays quickly for t 500 fs in this system, the contribution of the CSP approximation to the full Cl wavefunction is almost negligible. In addition, this wavefunction is dominated not by a few specific terms of the Cl expansion, but by a whole host of configurations. The decay of the CSP approximation was found to be due to hard collisions between the iodine atoms and the surrounding wall of argons. Already the first hard collision brings a major deterioration of the CSP approximation, but also the role of the second collision can be clearly identified. As was mentioned, for t < 80 fs, the CSP... 

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

Worenine. This alkaloid, also obtained by Kitasato from Coptis japonica was isolated as the tetrahydro-base, C,oHjg04N, which crystallises from alcohol in colourless prisms, m.p. 212-3°, and is oxidised by iodine in alcohol to worenine iodide, yellow crystals from which worenine chloride, thin orange-yellow prisms, m.p. 295° (dec.), can be obtained. Tetrahydro-worenine behaves as a tertiary base, contains methylenedioxy- but no methoxyl groups, and its absorption spectrum closely resembles that of tetrahydrocoptisine from which it differs in empirical composition by. CHj. Worenine is, therefore, represented by (XXX), the alternative position (a) for the methyl group being untenable, since a-methyltetra-hydrocoptisine obtained by Freund s method is not identical with... 

TLC analysis of the crude product (elution with 50 1 pentane ether, visualization with iodine) showed three non-baseline spots Rf 0.65 (cis isomer), Rf 0.52 (unknown impurity), and Rf 0.32 (trans isomer). The unknown impurity is intensely sensitive to iodine and largely coelutes with the cw-isomer in the subsequent column chromatography. However, the ll NMR spectrum of this isomer shows excellent purity despite the presence of this spot on TLC. In 100 1 pentane ether, Rf values of the cis and trans isomers are about 0.50 and 0.15, respectively. 

Most recently, we have been able to obtain the in situ surface EXAFS spectrum of a half-monolayer of underpotentially deposited copper on a bulk Pt(lll) single crystal pretreated with iodine. The spectrum shown in Fig. 23 is a bit noisy (due to limited number of scans) but at least five well-defined oscillations can be observed. Preliminary data analysis indicates that the copper adatoms sit on threefold hollow sites with copper neighbors at 2.80 0.03 A. This distance is very close to the Pt—Pt distance in the (111) direction and indicates the presence of a commensurate... 

Figure 23. In situ X-ray absorption spectrum for half a monolayer of copper underpotentially deposited on a bulk Pt (111) electrode pretreated with iodine.

A number of workers have used the GA to find values for the set of parameters in some predefined model. Hartfield s work on the interpretation of the spectrum of molecular iodine is typical.9 A particular difficulty with such an application is that the problem may well be deceptive, but because this may not be obvious from the form of the problem, the fit may be of lower quality than anticipated. 

Figure lb reports the UV-Visible spectrum of the liquid 1,4-bis(triethoxysilyl)benzene, the precursor of the phenylene-bridged PMO, into which traces of iodine have been dissolved. Only one band due to iodine is visible at 362 nm. We suggest this band to be due to I3" ion, which in aqueous solution absorbs at 355 nm [8], The presence of a band at the same wavelength in the case of I2 adsorbed onto AW-Ph-HMM reveals, also in... 

Beattie, I.R., Ozin, G.A., and Perry, R.O., Gas phase Raman spectra of P4, P2, As4 and As2. Resonance fluorescence spectrum of 80Se2. Resonance fluores-cence-Raman effects in the gas-phase spectra of sulfur and iodine. Effect of pressure on the depolarization ratios for iodine,. Chem. Soc., Perkin I, 2071, 1970. 

Soon after Dennison had deduced from the specific-heat curve that ordinary hydrogen gas consists of a mixture of two types of molecule, the so-called ortho and para hydrogen, a similar state of affairs in the case of iodine gas was demonstrated by direct experiment by R. W. Wood and F. W. Loomis.1 In brief, these experimenters found that the iodine bands observed in fluorescence stimulated by white light differ from those in the fluorescence excited by the green mercury line X 5461, which happens to coincide with one of the iodine absorption lines. Half of the lines are missing in the latter case, only those being present which are due to transitions in which the rotational quantum number of the upper state is an even integer. In other words, in the fluorescence spectrum excited by X 5461 only those lines appear which are due to what we may provisionally call the ortho type of iodine molecule. 

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