Effective ion temperature

Gronert S 1998 Estimation of effective ion temperatures in a quadrupole ion trap J. Am. Soc. Mass Spectrom. 9 845-8... 

In the above expression, K is the measured ionic mobility, N is the gas number density, is the ion s effective temperature, p is the ion-gas reduced mass term, and Oj(T ) is the averaged ion collision cross section. The effective ion temperature is a composite of the drift gas temperature and the energy the ion gains from the electric field ... 

Monte Carlo sim u lat ion s pro vide an altern ate approach to the generation of stable con form ation s. As with HyperCh ern s o th er simulation methods, the effects of temperature changes and solvation arc easily incorporated into th c ealcii lation s. 

The catalysed reaction was considered to arise from the heterolysis of dinitrogen pentoxide induced by aggregates of molecules of nitric acid, to yield nitronium ions and nitrate ions. The reaction is autocatalytic because water produced in the nitration reacts with the pentoxide to form nitric acid. This explanation of the mechanism is supported by the fact that carbon tetrachloride is not a polar solvent, and in it molecules of nitric acid may form clusters rather than be solvated by the solvent ( 2.2). The observation that increasing the temperature, which will tend to break up the clusters, diminishes the importance of the catalysed reaction relative to that of the uncatalysed one is also consistent with this explanation. The effect of temperature is reminiscent of the corresponding effect on nitration in solutions of nitric acid in carbon tetrachloride ( 3.2) in which, for the same reason, an increase in the temperature decreases the rate. 

Schematic illustrations of the effect of temperature and surface density (time) on the ratio of two isotopes, (a) shows that, generally, there is a fractionation of the two isotopes as time and temperature change the ratio of the two isotopes changes throughout the experiment and makes difficult an assessment of their precise ratio in the original sample, (b) illustrates the effect of gradually changing the temperature of the filament to keep the ratio of ion yields linear, which simplifies the task of estimating the ratio in the original sample. The best method is one in which the rate of evaporation is low enough that the ratio of the isotopes is virtually constant this ratio then relates exactly to the ratio in the original sample.

The electrical characteristics of ceramic materials vary gteady, since the atomic processes ate different for the various conduction modes. The transport of current may be because of the motion of electrons, electron holes, or ions. Electrical ceramics ate commonly used in special situations where reftactoriness or chemical resistance ate needed, or where other environmental effects ate severe (see Refractories). Thus it is also important to understand the effects of temperature, chemical additives, gas-phase equilibration, and interfacial reactions. 

The equations generally developed include all forms of the conduction. Eor example, to determine the flux or conductivity of ions in a soHd electrolyte as compared to electrons in a semiconducting ceramic, two terms are of interest the number of charge carriers and the mobiUty. The effects of temperature, composition, and stmeture on each of these terms must also be considered. 

In the plasma, the sample is vaporized and chemical bonds are effectively broken resulting in free atoms and ions. Temperatures of 5000-9000 K have been measured in the plasma compared to typical temperatures of 2000-3000 K in flames and graphite furnaces. 

Penton and Zollinger (1979, 1981 b) reported that this could indeed be the case. The coupling reactions of 3-methylaniline and A,7V-dimethylaniline with 4-methoxy-benzenediazonium tetrafluoroborate in dry acetonitrile showed a number of unusual characteristics, in particular an increase in the kinetic deuterium isotope effect with temperature. C-coupling occurs predominantly (>86% for 3-methylaniline), but on addition of tert-butylammonium chloride the rate became much faster, and triazenes were predominantly formed (with loss of a methyl group in the case of A V-di-methylaniline). Therefore, the initial attack of the diazonium ion is probably at the amine N-atom, and aminoazo formation occurs via rearrangement. 

From the earliest days of radiation chemistry it has been known that acetylene polymerizes to a cuprene-like ( alprene ) solid (5, 6,25,28). The characteristics of the polymerization—e.g., lack of effect of temperature, doso rate, and pressure on polymer yield and negligible effect of radical scavengers—led Lind (24) to postulate an ion cluster mechanism. 

Effects of Temperature on Ionic Reactions in TD/D2 CH4/ CD4. Observation that the methanium ion proton (deuteron) transfer sequence fails to exhibit a temperature coefficient within experimental uncertainties leads unavoidably to the conclusion that none of the reactions from 1 to 12 requires thermal activation between —78° and 25°C. From Equations I, II, III, appropriate steady state assumptions, and representing both neutralization steps by kX2, we find that... 

Zinc sulfide, with its wide band gap of 3.66 eV, has been considered as an excellent electroluminescent (EL) material. The electroluminescence of ZnS has been used as a probe for unraveling the energetics at the ZnS/electrolyte interface and for possible application to display devices. Fan and Bard [127] examined the effect of temperature on EL of Al-doped self-activated ZnS single crystals in a persulfate-butyronitrile solution, as well as the time-resolved photoluminescence (PL) of the compound. Further [128], they investigated the PL and EL from single-crystal Mn-doped ZnS (ZnS Mn) centered at 580 nm. The PL was quenched by surface modification with U-treated poly(vinylferrocene). The effect of pH and temperature on the EL of ZnS Mn in aqueous and butyronitrile solutions upon reduction of per-oxydisulfate ion was also studied. EL of polycrystalline chemical vapor deposited (CVD) ZnS doped with Al, Cu-Al, and Mn was also observed with peaks at 430, 475, and 565 nm, respectively. High EL efficiency, comparable to that of singlecrystal ZnS, was found for the doped CVD polycrystalline ZnS. In all cases, the EL efficiency was about 0.2-0.3%. 

The stability of a carbanion (or ion pair) is increased by certain substituents and decreased by others. It is possible to rank the various structures in an order of increasing stability of the carbanion just as was done for carbonium ions. It will be recalled that our information about carbonium ions does not suffice for a prediction of the effect of temperature changes on the relative stabilities, and that it is unknown to what degree an increase in stability actually reflects a decrease in potential energy. The situation is similar in the case of carbanions the precise relationship of the stabilities is an unknown function of the temperature. It is also likely that the effects of structural changes are somewhat dependent on the solvent. Nevertheless it is possible to make valuable qualitative comparisionsof the various structures and to interpret them in terms of resonance and other potential energy quantities. 

The total electrical resistance at room temperature includes the contribution from scattering of conduction electrons by the vacancies as well as by ion-core and impurity scattering. If the experiment is repeated at a number of high temperature anneals, then the effects of temperature on the vacancy contribution can be isolated, since the other two terms will be constant providing that... 

The effect of temperature on distribution ratios has already been mentioned on page 91. Although the separation proceeds more quickly at elevated temperatures, resolution suffers because of increased rates of diffusion. However, in adsorption TLC only small increases in Rt values are observed even with a 20°C rise. Strict temperature control is not necessary if samples and standards are run at the same time, although large fluctuations should be avoided. The quality of the thin-layer materials, and in particular the presence of impurities in them, determine the extent to which partition, adsorption, ion-exchange and exclusion participate in the sorption process. These factors affect Rr values in an unpredictable manner. Thin layers should be of uniform thickness, between 0.2 and 0.3 mm with thinner layers, local variations in thickness can result in appreciable variations in Rf values. 

Adam, L.C. Gordon, G. (1999) Hypochlorite ion decomposition effects of temperature, ionic strength, and chloride ion. Inorganic Chemistry, 38, 1299-1304. 

M. F. Powell, Stabibty of Lidocain in Aqueous Solution Effect of Temperature, pH, Buffer, and Metal Ions on Amide Hydrolysis , Pharm. Res. 1987, 4, 42-45. 

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