Aqueous solutions linewidth

In aqueous solution both the tetramer and the pentamer have cyclical structures (Fig. 6) as shown by the narrow 51V NMR linewidths indicating high symmetry around vanadium (29). The relative amounts of the species are concentration dependent but under moderate concentrations the tetramer is the most important (Figs. 2 and 3). The hexamer [V60i8]6 is a very minor species under most conditions, but it becomes somewhat more prominent at high concentrations and high ionic strength (8, 10, 15, 32). Indications are that it has a cyclic structure in aqueous solution (10). 

The broadening of the heme proton-resonances is mainly due to the increase in the rotational correlation time of the heme inside micelle. The increase in linewidth, Aoobs of a paramagnetic complex inside micelles compared to that in simple aqueous or non-aqueous solution is given as [20-22] ... 

Lithographic Characterization. Electron-beam exposures were conducted on an EBES system operating at 20 kV, with a beam address and spot size both equal to 0.25 ym. Electron response parameters were evaluated using linewidth control patterns. P(SI-CMS) was spray developed after exposure using an APT Model 915 resist processor in toluene-methanol (1 1) for 30 sec followed by a methanol rinse for 45 sec. Aqueous solutions of tetramethylammonium hydroxide (TMAH, 25% in water, Fluka Inc.) were used for the novolac resist development. Exposed films were dip-developed for 20 sec. in TMAH-water (1 2.5) solutions. 

As in the case of the concentration dependence of the chemical shift, the H and 13C band shapes of the surfactant resonance peaks are also concentration dependent. Analysis of H NMR band shapes for large aggregates of a cetyl trimethyl ammonium bromide-water system results in a CMC of 1.0 mM this is consistent with the value measured by other methods.57 The H NMR bands of alkyl trimethyl ammonium salicylate and hexadecyl pyridinium salicylate aqueous systems start to broaden at concentrations just above the CMC. The broadening continues up to a concentration above which the band shape is almost constant, as the concentration is further increased.-58 I3C NMR linewidth analysis of sodium octanoate in aqueous solution gives reasonable estimated CMC values.59... 

Complexes of MV+- radical cations included in cyclodextrin (CDx) were observed both in methanol/aqueous solutions and as microcrystalline powder.21 In the former situation, the spectral linewidth did not decrease monotonically with temperature, as is the case in the absence of CDx. The linewidth decrease... 

In these studies we have used solution NMR to study structure formation and the intermolecular interactions between the polymer and the matrix during the cure that affect the miscibility. The triblock copolymers form micelles in aqueous solution with the propylene oxide block at the center and the ethylene oxide block at the exterior (6), and micelle formation can be monitored via the proton linewidths. The NMR studies show that the triblock copolymers do not form micelles in the butanol solutions used for solution casting films of the low-k dielectrics, or in neat mixtures of the triblock copolymers with the methyl silsesquioxane. The methyl silsesquioxane starting material contains a... 

ABSTRACT. Raman spectra of several organic molecules which form hydrate clathrates have been measured in aqueous solution, and the.hydration structure around those molecules has been investigated from the analysis of Raman linewidth data. 

In this study, we succeeded in the observation of Raman spectra of benzene, cyclohexane and chloroform in aqueous solution. These molecules are known to form hydrate clathrates of type M 1TH20[2], and were selected because of their high solubilities in water, relative to other saturated hydrocarbons, and because of their strong Raman lines. It may be expected that the iceberg structure formed around the solute in aqueous solution affects the rotational motion of the solute molecule. Thus the rotational diffusion constants have been determined from the linewidths of the isotropic and anisotropic Raman spectra, and the effect of the iceberg structures on the rotational motion of the solute molecules is discussed from a comparison of the rotational diffusion constants in various solutions. 

The vibrational modes of the Raman lines used in this experiment belong to the totally symmetric species, so that the rotational diffusion constant obtained from their Raman linewidths is for the rotational motion (tumbling motion) of the solute molecule around the x axis perpendicular to the molecular z axis. Figs. 1-3 show the rotational diffusion constants obtained for benzene, cyclohexane and chloroform-d in aqueous solution and reference solution plotted against the reciprocal viscosity of the solvent. 

Figs. i+-5 show the isotropic Raman linewidths of t-butyl alcohol and isopropyl alcohol in aqueous solution and in nonpolar reference solvent, measured at a variety of concentrations. At first, the concentration dependence of the linewidths in nonpolar solvents is considered here. 

Figure Isotropic Raman linewidths of t-butyl alcohol in aqueous solution (closed circle) and in cyclohexane solution (open circle).

From these facts, it may he reasonably considered that the hydration structure around the alcohol molecules in aqueous solution is similar to the crystal structure of the hydrate clathrates. That is, around 0.05 mole fraction in aqueous solution, alcohol molecules are encaged in so limited spaces that the content of hydrogen bonded molecules is the largest, giving rise to the largest isotropic Raman linewidths. 

In this study, Raman spectra of several organic molecules have been measured in aqueous solution, and their linewidths have been analysed. As a result, it is concluded that the hydration structure like the crystal structure of the hydrate clathrate is formed around the solute molecules in aqueous solution. The results obtained in this study indicate that the Raman linewidth well reflects the hydration structure of organic molecules in aqueous solution. 

Assignment could be reversed. ) Spectrum of Cu(II) complex. Spectrum in da(N)/dr=0.189pTK- for CCI4 and 0 Line shape measurements of nitroxide ad pyridine has linewidth 6.2 mT.. 202nTK- for CH3OCH2CH2OCH3. sorbed onto silica gel in aqueous solution. ... 

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