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•Complex Ru(NO)(NO2)2(μ-NO2)(μ−CH3COO)(μ-O)VO(dbbpy)·CH3CN is platform, releasing NO in a solution under light exposure.•The irradiation of complex in solid state induce formation of ...Ru-ON linkage isomer reversibly decays to Ru-NO at 120−140 K.•The presence of vanadium influences the photochemical properties of ruthenium nitrosyl both in solid phase and in solution.
The work is devoted to the preparation and photochemical investigations of the novel binuclear heterometallic complex Ru(NO)(NO2)2(μ-NO2)(μ−CH3COO)(μ-O)VO(dbbpy)·CH3CN (dbbpy - 4,4′-di-tert-butyl-2,2′-bipyridyl), which is obtained with quantitative yield. The structure of the complex is determined by single crystal X-ray diffraction and by DFT calculations. On the one hand, irradiation at 445 nm of an acetonitrile solution of the complex leads to a NO photo-release reaction. The light excitation induces the charge transfer from NO2 and dbbpy ligands to the antibonding orbitals of ON-Ru-O-V chain, leading to the NO release, which is confirmed by the DFT. The quantum yield of the Ru-NO photo-cleavage is 0.57 ± 0.05 %. The products of the photolysis (NO and paramagnetic RuIII complex) are confirmed by the Griess test and EPR-spectroscopy. On the other hand, the irradiation of the complex in the solid phase at 10 K results in the formation of the metastable bond isomer Ru-ON (MS1), which is detected by the infrared spectroscopy. The stretching vibration of the ν(NO) band of MS1 (1750 cm−1) is shifted by 150 cm−1 to lower energy with respect to the ν(NO) band of the ground state GS (1900 cm−1). The population of the MS1 is about 5%. MS1 thermally decays at 120−140 K back to the GS. Hence, this complex represents a bifunctional platform, which can release nitric oxide in solution and reversibly switch the NO ligand coordination in the solid state. It is shown, that the presence of vanadium strongly influences the photochemical properties of ruthenium nitrosyl both in the solid phase and in solution.
In this work, a consolidated experimental apparatus for measuring the density of liquids, such as high pressure and metastable states, based on the isochoric method, was exploited to measure thermal ...properties of seawater. Density of standard seawater was measured in a wide range of temperature and pressure, specifically from (261.15 to 313.15) K and up to 110 MPa. All terms contributing to the uncertainty in determining the volume and the mass of the specimen were evaluated, obtaining a relative expanded uncertainty of seawater density around 0.03% (k=2). Experimental results were fitted by using a 8-parameters function of specific volume as a function of temperature and pressure. Using the obtained expression, density, isobaric thermal expansion, and isothermal compressibility of seawater were calculated from (263.15 to 313.15) K and for pressures between (1 and 105) MPa. A comparison with the predictions obtained by the Thermodynamic Equation of Seawater - 2010 (TEOS-10) shows a general good agreement that worsens when metastable states are considered.
•Density measurements of standard seawater from (261.15 to 313.15) K and up to 110 MPa.•Estimation of the relative uncertainty of seawater density.•Comparison between the experimental results and the reference equation of state.•Implementation of a 8-parameters function of specific volume to calculate density.•Calculation of seawater isobaric thermal expansion and isothermal compressibility.
We investigate dissociation in flight of metastable molecular dications formed by ultrashort, intense laser pulses using the cold target recoil ion momentum spectroscopy technique. A method for ...retrieving the lifetime(s) of the transient metastable state(s) as well as the complete three-dimensional momenta of the dissociating fragments is presented. Specifically, we demonstrate and discuss this approach by focusing on dissociation in flight of the ethylene dication going to the deprotonation channel. Two lifetimes are found to be associated with this process, C2H 4 2 + → C2H3+ + H+: τ 1 = 202 10 ns and τ 2 = 916 40 ns. For the corresponding channel in deuterated ethylene, lifetimes of τ 1 = 269 29 ns and τ 2 = 956 83 ns are obtained.
When liquids are cooled sufficiently rapidly below their melting temperature, they may bypass crystalization and, instead, enter a long-lived metastable supercooled state that has long been the focus ...of intense research. Although they exhibit strikingly different properties, both the (i) long-lived supercooled liquid state and (ii) truly equilibrated (i.e., conventional equilibrium fluid or crystalline) phases of the same material share an identical Hamiltonian. This suggests a mapping between dynamical and other observables in these two different arenas. We formalize these notions via a simple theorem applicable to general systems and illustrate that given a Hamiltonian defining the dynamics: (1) the reduced probability densities of all possible stationary states are linear combinations of reduced probability densities associated with thermal equilibria at different temperatures, chemical potentials, etc. (2) Excusing special cases, amongst all of these stationary states, a clustering of correlations is only consistent with conventional thermal equilibrium states (associated with a sharp distribution of the above state variables). (3) Other stationary states may be modified so as to have local correlations. These deformations concomitantly lead to metastable (yet possibly very long-lived) states. Since the lifetime of the supercooled state is exceptionally long relative to the natural microscopic time scales, their reduced probability densities may be close to those that we find for exact stationary states (i.e., a weighted average of equilibrium probability densities at different state variables). This form suggests several new predictions such as the existence of dynamical heterogeneity stronger than probed for thus far and a relation between the specific heat peak and viscosities. Our theorem may further place constraints on the putative “ideal glass” phase.
•We link reduced probability densities of long-lived states to those in equilibrium.•This relates supercooled liquids to their equilibrium (solid and fluid) counterparts.•This framework suggests non-Maxwellian velocities in supercooled liquids.•A prediction for the viscosity conforms with all available experimental data.
We performed spectroscopic measurements of the 3snp (21 ≤ n ≤ 51) 3P° and the 3snf (26 ≤ n ≤ 55) 3F° Rydberg states of magnesium (Mg) atom using two-step laser resonant excitation of Mg in the ...3s3p3P° metastable states. The metastable states of Mg were produced in a pulsed discharge, which was initiated each time a Mg rod was ablated by a pulsed Nd:YAG laser in between low-voltage electrodes. The quantum defects of the 3snp3P0,1∘ and the 3snf3F2,3∘ states were determined as 1.114(6) and 0.04(1), respectively.
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•Systematic laser spectroscopy of Mg triplet 3snp and 3snf Rydberg states has been done.•Triplet Rydberg states have been excited starting from the triplet metastable states.•The metastable Mg atoms are produced using laser-ablation initiated discharge.
The search for low-energy antideuterons in cosmic rays allows the addressing of fundamental physics problems testing for the presence of primordial antimatter and the nature of Dark Matter. The ...PHeSCAMI (Pressurized Helium Scintillating Calorimeter for AntiMatter Identification) project aims to exploit the long-living metastable states of the helium target for the identification of low-energy antideuterons in cosmic rays. A space-based pressurized helium calorimeter would provide a characteristic identification signature based on the coincident detection of a prompt scintillation signal emitted by the antideuteron energy loss during the slowing-down phase in the gas, and the (≈µs) delayed scintillation signal provided by the charged pions produced in the subsequent annihilation. The performance of a high-pressure (200-bar) helium scintillator prototype, tested in the INFN-TIFPA laboratory, will be summarized.
•Unified equation of state for a liquid and vapor Lennard-Jones (LJ) mixture obtained.•The mechanical and diffusion stability conditions of binary LJ mixtures are considered.•The phase equilibrium ...parameters are calculated.•The diffusion and mechanical spinodals of the mixture were determined.
The mechanical and diffusion stability conditions of binary Lennard-Jones mixtures with respect to infinitesimal changes in state parameters are considered. In stable and metastable states, by molecular dynamics method, the pressure is determined as a function of temperature, density and composition of a Lennard-Jones mixture simulating the methane–nitrogen system. The phase equilibrium parameters are calculated. Based on the data obtained, a unified mixture state equation for liquid and vapor was created. The diffusion and mechanical spinodals of the mixture were determined.
•The effect of a polarized current on Néel vector transitions are considered.•Quantum and thermal transition rates are derived.•Dependence on temperature, magnetic field and polarized current are ...given.•The effect of dissipation can be diminished by a polarized current.•The results extend macroscopic quantum phenomena in spintronics.
We study transitions of the Néel vector out of a metastable state to a more stable one in the presence of a polarized current. The discussion is general although the system considered is an antiferromagnetic spintronic. The presence of the current allows one to study transitions of the Néel vector as a function of temperature with the effect of dissipation that can be varied from positive to negative depending on the sign of the current. This is different than the usual case where one only has one type of positive dissipation when only magnetic field is being applied to an antiferromagnet. Using the method of path integral, we derive the expression for the rate of transitions of the Néel vector. A cross-over temperature T0 between quantum and thermal transitions is determined. The expressions for the rates of quantum transitions below the cross-over temperature, and of thermal transitions at and above it are presented. The expression of the polarized current that diminishes the effect of dissipation is also presented as a function of temperature.
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