Abstract Due to its high energy efficiency and environmental friendliness, solid-state cooling based on the barocaloric (BC) effect represents a promising alternative traditional refrigeration technologies relying greenhouse gases. Plastic crystals displaying orientational order-disorder solid-solid phase transitions have emerged among most gifted materials which realize full potential of BC cooling. However, comprehensive understanding atomistic mechanisms effects are sustained is still...

The motion of phospholipids has previously been studied on many time scales due to the significance for living cells and technological applications. motions a pico- nanosecond scale were determined by quasielastic neutron scattering (QENS) be much faster than ones microsecond covered fluorescence recovery after photobleaching (FRAP). This was explained assuming that molecules rattle fast in cage neighbors (observed with QENS) from which they escape once while; this then primary step slower...

SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German source FRM II and operated by Jülich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, dynamic range of ± 31 signal-to-noise ratio up to 1750:1.

In recent years, orientationally disordered crystals, or plastic have transformed the field of solid-state cooling due to significant latent heat and entropy changes associated with their temperature induced molecular order-disorder phase transition, which can produce colossal caloric effects under external stimuli. However, mechanisms underlying these huge remain inadequately understood, general principles for enhancing performance crystals are lacking. Previous studies predominantly...

The dynamics of a simple rigid pseudoglobular molecule (2-adamantanone) has been studied by means dielectric spectroscopy and examined under the constraints imposed space group crystal structure determined x-ray powder diffraction. low-temperature monoclinic 2-adamantanone, with one per asymmetric unit (${Z}^{\ensuremath{'}}=1$), displays statistical intrinsic disorder, concerning site occupancy oxygen atom along three different sites. Such physically identifiable disorder gives rise to...

Both structural glasses and disordered crystals are known to exhibit anomalous thermal, vibrational, acoustic properties at low temperatures or energies, what is still a matter of lively debate. To shed light on this issue, we studied the halomethane family ${\mathrm{CBr}}_{n}{\mathrm{Cl}}_{4\ensuremath{-}n}$ ($n=0,1,2$) temperature where, despite being perfectly translationally ordered stable monoclinic crystals, glassy dynamical features had been reported from experiments molecular...

A new type of materials combining a high-temperature plastic phase and low-temperature ferroelectric phase, the crystals, are promising for application in refrigeration systems based on solid-state caloric effects.

We have performed a detailed dielectric investigation of the relaxational dynamics glass-forming benzophenone. Our measurements cover broad frequency range $0.1\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}120\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$ and temperatures from far below glass temperature well up into region small-viscosity liquid. With respect to $\ensuremath{\alpha}$ relaxation this material can be characterized as typical...

The dynamics of simple molecular systems showing glassy properties has been explored by dielectric spectroscopy and nuclear quadrupole resonance (NQR) on the halogenomethanes CBr2Cl2 CBrCl3 in their low-temperature monoclinic phases. spectra display features which correspond to alpha- beta-relaxation processes, commonly observed canonical glass formers. NQR experiments, also performed ergodic phase CCl4, enable determination microscopic mechanism underlying beta these model glasses:...

The microscopic structure of the tryptophan side chain, indole, in an amphiphilic environment has been investigated using a combination neutron diffraction measurements and simulations solution. results show that indole is preferentially solvated by hydrogen bonding interactions between water alcohol -OH groups rather than interaction being dominated indole-methyl interactions. This implications for understanding how interacts with amphipathic membrane to anchor proteins into membranes,...

The stable solid polymorphism of cyclooctanol $({\mathrm{C}}_{8}{\mathrm{H}}_{16}\mathrm{O},$ for short ${\mathrm{C}}_{8}--\mathrm{OH})$ is revealed to be a complex problem and only two phases, denoted on cooling from the liquid as phases I II, are found using static (thermodynamic x-ray diffraction) well dynamic (dielectric spectroscopy) experimental techniques. Both known exhibit glass transitions if they cooled down fast enough prevent transition ordered crystalline states. Although...

The thermal conductivity $\ensuremath{\kappa}(T)$ of the fully ordered stable phase II, metastable III, orientationally disordered (plastic) I, as well nonergodic orientational glass (OG) phase, former cyclohexanol (C${}_{6}$H${}_{11}$OH) has been measured under equilibrium vapor pressure within 2--200 K temperature range. main emphasis is here focused on influence conformational disorder upon properties this material. Comparison results with those regarding cyanoclyclohexane...

Molecular interactions for proline in a highly concentrated aqueous solution (up to 1:5 proline:water molecular ratio) have been investigated using variety of experimental and computational techniques. Rather than the containing either small crystallites or large aggregates proline, three-dimensional structural analysis reveals presence proline-proline dimers. These dimers appear be formed by cyclic electrostatic between CO2(-) NH2(+) groups on neighboring molecules, which causes ring motifs...

The polymorphism of bromotrichloromethane (CBrCl3) has been investigated by X-ray powder diffraction and high-pressure density experiments. Phase transitions as a function temperature pressure between the different phases have characterized at normal well high pressures (up to 300 MPa). From p−v−T diagram (and derived p−T diagram) volume variations transition points calculated compared with those obtained means characterization. Special attention is given lattice symmetry orientational...

We present a thorough dielectric investigation of the relaxation dynamics plastic crystalline Freon112, which exhibits freezing orientational degrees freedom into glassy crystal below 90K. Among other crystals, Freon112 stands out by being relatively fragile within Angell’s [Relaxations in Complex Systems, edited K. L. Ngai and G. B. Wright (NRL, Washington, DC, 1985), p. 3] classification scheme showing an unusually strong β relaxation. Comparing results to those on Freon112a, having only...

The thermal conductivity, specific heat, and volume of the orientational glass former 1,1,2-trichloro-1,2,2-trifluoroethane (CCl2F-CClF2, F-113) have been measured under equilibrium pressure within low-temperature range, showing thermodynamic anomalies at ca. 120, 72, 20 K. results are discussed together with those pertaining to structurally related 1,1,2,2-tetrachloro-1,2-difluoroethane (CCl2F-CCl2F, F-112), which also shows 130, 90, 60 rich phase behavior these compounds can be accounted...

Investigations on the β-turn forming peptide, GPG, suggest that urea denatures proteins by replacing water molecules and subsequently weakening peptide bonds as a possible mechanism of protein denaturation urea.

We present a dynamic and thermodynamic study of the orientational glass former Freon 113 (1,1,2-trichloro-1,2,2-trifluoroethane, ${\mathrm{CCl}}_{2}\mathrm{F}\text{\ensuremath{-}}{\mathrm{CClF}}_{2}$) in order to analyze its kinetic fragilities. displays internal molecular degrees freedom that promote complex energy landscape. Experimental specific heat microscopic origin, vibrational density states from inelastic neutron scattering, together with dynamics obtained by means dielectric...

We report a thorough characterization of the glassy dynamics benzophenone by broadband dielectric spectroscopy. detect well-pronounced beta relaxation peak developing into an excess wing with increasing temperature. A previous analysis results from Optical-Kerr-effect measurements this material within mode-coupling theory revealed high-frequency Cole-Cole peak. address question if phenomenon also may explain Johari-Goldstein relaxation, so-far unexplained spectral feature inherent to...

We report on the interplay between short-range order of molecules in liquid phase 1,1,2,2-tetrachloro-1,2-difluoroethane and possible molecular conformations, trans gauche. Two complementary approaches have been used to get a comprehensive picture: analysis neutron-diffraction data by Bayesian fit algorithm dynamics simulation. The results both show that population gauche conformers state can only correspond conformer being more stable than conformer. Distinct geometries induce distinct...

Glassy dynamics of rigid molecules is still a matter controversy: the physics behind relaxation process at time scales faster than that ruled by viscosity, so called Johari-Goldstein process, not known. In this work we unravel mechanism such using simple molecular model in which centers mass are forming an ordered lattice, and reorientation performed jumps between equilibrium orientations. We have studied quasi-tetrahedral CBr(n)Cl(4-n), n = 0, 1, 2, their monoclinic phases means dielectric...

The heat capacity and thermal conductivity of the monoclinic fully ordered orthorhombic phases 2-adamantanone (C10H14O) have been measured for temperatures between 2 150 K. capacities both are shown to be strikingly close regardless site disorder present in crystal which arises from occupancy three nonequivalent sites oxygen atom. curves also well accounted by an evaluation carried out within harmonic approximation terms g(ω) vibrational frequency distributions means inelastic neutron...

A combination of neutron diffraction and computation has been used to investigate the atomic scale structure cocaine in aqueous solutions.

Abstract Water is the most important plasticizer of biological and organic hydrophilic materials, which generally exhibit enhanced mechanical softness molecular mobility upon hydration. The enhancement dynamics mixing with water, in glass-forming systems implies a lower glass transition temperature ( T g ), considered universal result In fact, even cases where hydration or humidification an sample stiffer properties, almost always increases increasing water content, its decreases...