Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/125/4/10.1063/1.2217738.Transient absorption measurements monitor the geminate recombination kinetics of solvated electrons following two-photonionization of liquid water at several excitation energies in the range from 8.3to12.4eV. Modeling the kinetics of the electron reveals its average ejection length from the hydronium ion and hydroxyl radical counterparts and thus provides insight into the ionization mechanism. The electron ejection length increases monotonically from roughly 0.9nm at 8.3eV to nearly 4nm at 12.4eV, with the increase taking place most rapidly above 9.5eV. We connect our results with recent advances in the understanding of the electronic structure of liquid water and discuss the nature of the ionization mechanism as a function of excitation energy. The isotope dependence of the electron ejection length provides additional information about the ionization mechanism. The electron ejection length has a similar energy dependence for two-photonionization of liquid D(2)O, but is consistently shorter than in H(2)O by about 0.3nm across the wide range of excitation energies studied

Observation of Crossover from Ballistic to Diffusion Regime for Excimer Molecules in Superfluid 4^4He

We have measured the temperature dependence of the time of flight of helium excimer molecules He2* in superfluid 4He and find that the molecules behave ballistically below 100mK and exhibit Brownian motion above 200 mK. In the intermediate temperature range the transport cannot be described by either of the models.Comment: 8 pages, 6 figures, submitted to the Proceedings of the International Conference on Quantum Fluids and Solids 201

Volume, enthalpy and entropy of activation of the diels-alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with 1-hexene

Pressure and temperature effects on the reaction rate of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with 1-hexene were investigated. The activation volume (-26.7 cm3 mol1, 298.1 K) is in agreement with the conservation of all four nitrogen atoms in transition state. Densitometry, 1H NMR and calorimetric studies of the reaction indicate nitrogen molecule loss by the intermediate just after its formation. Partial molar volumes in acetone of diene (127.2), 1-hexene (127.6) and the resulting adduct (206.9 cm3 mol-1) were determined

Volume parameters of some Diels - Alder reactions involving C=C, C=S, and N=N bonds

The effect of a hydrostatic pressure of up to 1000 kg cm-2 on the rate constants of the Diels - Alder reactions of maleic anhydride with 1,2,3,4-tetraphenylcyclopentadiene and with 6,13-dichloropentacene, of 4-phenyl-1,2,4-triazoline-3,5-dione with hexachlorocyclopentadiene, and of thiobenzophenone with isoprene was studied at 25°C. The volume parameters and ratios of the activation to reaction volumes make it possible to exclude electrostriction of the solvent during transition state solvation in all the reactions studied, which corresponds to the nonpolar nature of the transition state. © 2005 Springer Science+Business Media, Inc

Solvent effect on the heat of solution and partial molar volume of some non-electrolytes and lithium perchlorate

For several non-electrolytes and for lithium perchlorate the solvent effect on the heat of solution and partial molar volumes was studied. In the absence of the donor-acceptor and electrostatic interactions, clear proportionality can be seen only in the alkane solutions and these changes are defined by the non-alkane component. For solutions of π-acceptor (tetracyanoethylene) and v-acceptor (gallium chloride) in the presence of π,π-, π,V- and n,v-complexes, the relation between the changes of interaction energy and the values of the partial molar volumes can be seen. The maximum change in the value of partial molar volumes (up to 50cm mo1-1) was noted for lithium perchlorate in ten solvents. The volume change is proportional to the compressibility coefficients of the solvents and correlates less with the values of heat of solution and solvent permittivity. Copyright © 2006 John Wiley & Sons, Ltd

Effect of Elevated External Pressure on the Rate of the Diels-Alder Reaction of 9-Methylanthracene with Acrylonitrile, Catalyzed by Gallium Chloride

External pressure was found to similarly affect the rate of a gallium chloride-catalyzed Diels-Alder reaction between 9-methylanthracene with acrylonitrile and a noncatalyzed reaction of 9,10-dimethyl-anthracene with acrylonitrile. The observation of equal activation volumes is consistent with the assumption that elevated pressure very weakly affects the bond energy in the n,v complex of acrylonitrile with gallium chloride

Activation and reaction volumes for [4 + 2] and [3 + 2] additions involving maleic anhydride

The partial molar volumes of reactants and products of the [3 + 2] addition of C-(p-nitrophenyl)-N-phenylnitrone to maleic anhydride and of the [4 + 2] addition of 9,10-dimethylanthracene to the same dienophile were determined, and the reaction volumes were calculated. A new method was suggested for determining the reaction volume. The activation volumes of both reactions were calculated from the dependences of the reaction rates on the external pressure. The volume parameters of the reactions involving the reagents of close size are close. The ratios of the activation volumes to the reaction volumes are unity, which suggests a common concerted mechanism of the reactions. Factors that could be responsible for significant changes in the absolute values of the reaction volume parameters are discussed

Solvent effect on the volume of the DielsAlder reaction between tetracyanoethylene and trans,trans-1,4-diphenyl-1,3-butadiene

From the partial molar volumes of tetracyanoethylene, trans,trans-1,4-diphenyl-1,3-butadiene, and their Diels-Alder adduct, the volumes of the reaction in a series of solvents at 25°C (cm3 mol-1) were calculated: in dioxane, -26.4; in chloroform, -34.9; in ethyl acetate, -34.5; in acetonitrile, -4.4; in cyclohexanone, -34.0; in 1,2-dichloroethane, -31.8; in benzene, -26.9; in toluene, -24.5; in o-xylene, -21.1; and in mesitylene, -16.9. The solvent effects on the activation and reaction volumes and on the partial molar volumes of the reactants, activated complex, and adduct were discussed

Experimental study of the strength characteristics of fixation of the symphysis pubis with an original plate for the reconstruction of the anterior pelvic semi-ring

The destabilization of bone fixators has led to repeated surgical interventions that increased the risk of migrations of metal fixators, infectious and inflammatory complications as well. The modern trends in hip bone injury surgery are related to developing and using of metal fixators, which are effective in acute injury; however, sometimes the condition of the patient and the technical support of hospitals don’t allow performing surgery in the acute period, and these metal fixators are ineffective for chronic damage. Consequently, until now, the problem of finding the optimal design of structures for fixing chronic damage of anterior pelvic semi-ring which will be able to exclude its destabilization, is still of current interest.The purpose of the study: developing and experimental researching of durable features of original plate for reconstruction of the anterior pelvic semi-ring.Materials and methods: In order to ensure stable fixation of chronic pelvic injuries, the original metal plates have been worked out. They are made individually in accordance with the anatomical and functional structures of the anterior pelvic semi-ring of the patient with using additive technologies. The study of the reliability of the different variants of ostiosynthesis of the anterior pelvic semi-ring with using well-known pelvic plates and a new original design was carried out. Stability tests for different plate fixing methods and mechanical strength of metallophyxators were carried out on a universal test machine of LFM-50kN series.Results: one plate fixation in tensile test showed the lowest result – 0.341 kN, a low result of shear loads was received with the same object. The best result was shown by the polyaxial monolithic plate fixation in case of stretching – 0.51 kN at the shear loads – 0.591 kN. Necessary force applied to destabilizing of the metal structure while using a polyaxial monolithic plate was a half-higher than stretched, and a third higher than at shear loads, it demonstrates the benefits of using these metal fixators.Conclusion: It is experimentally confirmed that the polyaxial monolithic plate provides the highest stability of fixing anterior pelvic semi-ring indicator in contrast with fixing of one or two plates