STRUCTURE OF CYCLOHEXANE t-BUTANOL MIXTURES FROM POSITRON ANNIHILATION AND ULTRASONIC VELOCITY MEASUREMENTS

The densities of and sound velocities in t-butyl alcohol solutions in cyclohexane were determined in the temperature range 25 to 45°C. From these data adiabatic compressibility coefficients of the solutions were calculated, as well as excess densities and compressibilities. The positron annihilation spectra of the solutions were measured at room temperature. The results plotted against alcohol concentration show structural processes, which can be attributed to dimerization of the solute molecules

Measurement of double beta decay of ¹⁰⁰Mo to excited states in the NEMO 3 experiment

The double beta decay of ¹⁰⁰Mo to the 0_{1}^{+} and 2_{1}^{+} excited states of ¹⁰⁰Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of ¹⁰⁰Mo to the excited 0_{1}^{+} state is measured to be T_{1/2}^{2v} = [5.7_{-0.9}^{+1.3} (stat.) ± 0.8 (syst.)] x 10²⁰ y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 0_{1}^{+} state has been found. The corresponding half-life limit is T_{1/2}^{0v} (0⁺→0_{1}^{+}) > 8.9 x 10²² y (at 90% C.L.). The search for the double beta decay to the 2_{1}^{+} excited state has allowed the determination of limits on the half-life for the two neutrino mode T_{1/2}^{0v} (0⁺→2_{1}^{+}) > 1.1 x 10²¹ y (at 90% C.L.) and for the neutrinoless mode T_{1/2}^{0v} (0⁺→2_{1}^{+}) > 1.6 x 10²³ y (at 90% C.L.)

Measurement of double beta decay of 100Mo to excited states in the NEMO 3 experiment

The double beta decay of 100Mo to the 0^+_1 and 2^+_1 excited states of 100Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of 100Mo to the excited 0^+_1 state is measured to be T^(2nu)_1/2 = [5.7^{+1.3}_{-0.9}(stat)+/-0.8(syst)]x 10^20 y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 0^+_1 state has been found. The corresponding half-life limit is T^(0nu)_1/2(0^+ --> 0^+_1) > 8.9 x 10^22 y (at 90% C.L.). The search for the double beta decay to the 2^+_1 excited state has allowed the determination of limits on the half-life for the two neutrino mode T^(2nu)_1/2(0^+ --> 2^+_1) > 1.1 x 10^21 y (at 90% C.L.) and for the neutrinoless mode T^(0nu)_1/2(0^+ --> 2^+_1) > 1.6 x 10^23 y (at 90% C.L.).Comment: 23 pages, 7 figures, 4 tables, submitted to Nucl. Phy

Structure of Carbon Tetrachloride + t-Butanol Mixtures from Positron Annihilation and Ultrasonic Velocity Measurements

The densities of and sound velocities in t-butyl alcohol solutions in CCl$\text{}_{4}$ were determined in temperature range 25 to 45°C. From these data the adiabatic compressibility coefficients of the solutions were calculated, as well as excess densities and compressibilities. The positron annihilation spectrum for this system in room temperature was measured. The results plotted against alcohol concentration suggest that the structural processes occurring in this system are caused by dimerization of the solute molecules

Structure of Cyclohexane + t-Butanol Mixtures from Positron Annihilation and Ultrasonic Velocity Measurements

The densities of and sound velocities in t-butyl alcohol solutions in cyclohexane were determined in the temperature range 25 to 45°C. From these data adiabatic compressibility coefficients of the solutions were calculated, as well as excess densities and compressibilities. The positron annihilation spectra of the solutions were measured at room temperature. The results plotted against alcohol concentration show structural processes, which can be attributed to dimerization of the solute molecules

Hydrophobic-Like Solvation in Non-Aqueous Solutions: Positron Annihilation in and Compressibility of Tert-butanol and Tetramethylurea in Ethylene Glycol

The pioneer experimental results of positron annihilation experiments in non-aqueous solutions of tetramethylurea and tert-butanol were compared to those of ultrasonic velocity. For tert-butanol, the positron annihilation results exclude existence of hydrophobic-like interactions and formation of weak, labile crystalline-like solvates in solution. For tetramethylurea solute the changes of annihilation parameters with concentration are minor and only limited conclusions can be drawn on this system, while they are stronger for tert-butanol solute. However, all the above is consistent with an assumption that the more hydrophobic solute (tert-butanol) should affect the original glycol structure stronger than that interacting with glycol via hydrogen bondings only. On the other hand, the ultrasonic data for the systems tested, although very precise, hardly confirm formation of any specific structure. It is possible, however, that the solvates do not differ in their compressibility from the pure liquids, and/or are formed only in very small amounts. Thus, usefulness of the positron annihilation method in investigation of liquid structure was proven

Structure of Aqueous Solutions of 1,2- and 1,3-Propanediol Investigated by Positron Annihilation and Ultrasonic Methods

The structure of aqueous solutions of 1,2-propanediol and 1,3-propane-diol was investigated using adiabatic compressibility measurements and positron annihilation methods. The experimental results are different than those obtained earlier for systems where hydrophobic hydration dominates. There are some evidences for increased rigidity of the water network, which can arise from the formation of hydrogen bonds between diols and water

Positron Annihilation in and Compressibility of Water-Organic Mixtures. The System Water-Acetamide

The experimental results of positron annihilation experiments in aqueous solutions of acetamide were compared to those of ultrasonic velocity. The system under investigation behaves untypically when changing acetamide concentration. From the point of view of surface tension it interacts with water like normal alcohols, while the positron annihilation and ultrasonic results suggest hydrophilic hydration and lack of hydrophobic interactions