Pressure dependence of Sm:YAG fluorescence to 50 GPa: A new calibration as a high pressure scale

1994 ◽  
Vol 75 (3) ◽  
pp. 1463-1466 ◽  
Author(s):  
Hitoshi Yusa ◽  
Takehiko Yagi ◽  
Haruo Arashi
Keyword(s):  
High Pressure ◽  
Pressure Dependence ◽  
Pressure Scale

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

Intermolecular Interactions of Xe Atoms Confined in One-dimensional Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene as Studied by High-pressure 129Xe NMR

2003 ◽  
Vol 58 (12) ◽  
pp. 727-734 ◽  
Author(s):  
Hirokazu Kobayashi ◽  
Takahiro Ueda ◽  
Keisuke Miyakubo ◽  
Taro Eguchi
Keyword(s):  
High Pressure ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Pressure Dependence ◽  
Average Distance ◽  
Chemical Shift Tensor ◽  
Axially Symmetric ◽  
One Dimensional ◽  
129Xe Nmr ◽  
The One

The pressure dependence of the 129Xe chemical shift tensor confined in the Tris(o-phenylenedioxy) cyclotriphosphazene (TPP) nanochannel was investigated by high-pressure 129Xe NMR spectroscopy. The observed 129Xe spectrum in the one-dimensional TPP nanochannel (0.45 nm in diameter) exhibits a powder pattern broadened by an axially symmetric chemical shift tensor. As the pressure increases from 0.02 to 7.0 MPa, a deshielding of 90 ppm is observed for the perpendicularcomponent of the chemical shift tensor δ⊥, whereas a deshielding of about 30 ppm is observed for the parallel one, δ‖. This suggests that the components of the chemical shift tensor, δ‖ and δ⊥, are mainly dominated by the Xe-wall and Xe-Xe interaction, respectively. Furthermore, the effect of helium, which is present along with xenon gas, on the 129Xe chemical shift is examined in detail. The average distance between the Xe atoms in the nanochannel is estimated to be 0.54 nm. This was found by using δ⊥ at the saturated pressure of xenon, and comparing the increment of the chemicalshift value in δ⊥ to that of a β -phenol/Xe compound.

XII.—On the Theory of Unimolecular Gas Reactions: A Quantum Harmonic Oscillator Model

1954 ◽  
Vol 64 (2) ◽  
pp. 161-174 ◽  
Author(s):  
N. B. Slater
Keyword(s):  
High Pressure ◽  
Classical Mechanics ◽  
Classical Case ◽  
Constant Factor ◽  
Quantum Case ◽  
Fundamental Vibration ◽  
Fixed Temperature ◽  
Dissociation Probability ◽  
Pressure Scale ◽  
Continuum Of States

SynopsisThe writer's theory of unimolecular dissociation rates, based on the treatment of the molecule as a harmonically vibrating system, is put in a form which covers quantum as well as classical mechanics. The classical rate formulæ are as before, and are also the high-temperature limits of the new quantum formulæ. The high-pressure first-order rate k∞ is found first from the Gaussian distribution of co-ordinates and momenta of harmonic systems, and is justified for the quantum-mechanical case by Bartlett and Moyal's phase-space distributions. This leads to a re-formulation of k∞ as a molecular dissociation probability averaged over a continuum of states, and to a general rate for any pressure of the gas.The high-pressure rate k∞ is of the form ve-F/kT, where v and F depend, in the quantum case, on the temperature T; but v is always between the highest and lowest fundamental vibration frequencies of the molecule. Concerning the decline of the general rate k with pressure at fixed temperature, k/k∞ is to a certain approximation the same function of as was tabulated earlier for the classical case, apart from a constant factor changing the pressure scale in the quantum case.

Free Activation Energies and Activation Volumes for the Amide Rotation in Some Peptides Studied by High Pressure 1H-High Resolution NMR

1982 ◽  
Vol 37 (1-2) ◽  
pp. 51-56 ◽  
Author(s):  
H. Hauer ◽  
H.-D. Lüdemann ◽  
R. Jaenicke
Keyword(s):  
High Pressure ◽  
High Resolution ◽  
Pressure Dependence ◽  
Nmr Spectra ◽  
Conformational Transition ◽  
Activation Energies ◽  
High Resolution Nmr ◽  
Maximum Contribution ◽  
The Given ◽  
Amide Rotation

From the pressure dependence of 1H high resolution NMR spectra of two dipeptides (glycylsarcosine and N-acetyl-ʟ-proline-NH-methylamide in the range 0.1 MPa ≤p ≤ 150 MPa the activation volumes ⊿V≠ for the amide rotation are derived. This conformational transition is characterized for glycylsarcosine by ⊿V≠ = 4 ± 1 cm3 · mol-1 and for. the proline derivative by ⊿V≠ = 7.5±1 cm3 · mol-1. From the given results the maximum contribution of proline cis ⇌ trans isomerisation to the pressure dependence of the rate of reactivation of proteins can be estimated to ~ - 30% per MPa and proline present.

High-pressure dependence of Raman phonons of R MnO 3 ( R=Pr,Tb )

2003 ◽  
Vol 171 (1-2) ◽  
pp. 313-316 ◽  
Author(s):  
L. Martín-Carrón ◽  
J. Sánchez-Benítez ◽  
A. de Andrés
Keyword(s):  
High Pressure ◽  
Pressure Dependence

The Pressure Dependence of the Rotation of the N-Aralkyl- pyridinium Moiety in a Synthetic NAD+ Model System Studied by High Pressure HRNMR

1981 ◽  
Vol 36 (5-6) ◽  
pp. 366-368 ◽  
Author(s):  
Johann Hauer ◽  
Hans-Dietrich Lüdemann ◽  
J. W. Verhoeven
Keyword(s):  
High Pressure ◽  
Pressure Dependence ◽  
Activation Volume ◽  
Model System

Abstract High Pressure, NMR, NAD +-Model, Activation Volume The activation volume ⊿V* for the rotation of the N -aralkylpyridinium moiety in a synthetic NAD + model was studied by high pressure HRNMR. From the pressure dependence of the proton spectra a negative ⊿V* of -3 cm3 · mol-1 is derived. It is concluded from this result, that the rotation of the N -aralkylpyridinium ring occurs in a complex geared m otion and not in 180°-flips.

scholarly journals High temperature superconductivity in sulfur hydride under ultrahigh pressure: A complex superconducting phase beyond conventional BCS

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Annette Bussmann-Holder ◽  
Jürgen Köhler ◽  
M.-H. Whangbo ◽  
Antonio Bianconi ◽  
Arndt Simon
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Transition Temperature ◽  
Hydrogen Bonds ◽  
Pressure Dependence ◽  
High Temperature Superconductivity ◽  
Superconducting Phase ◽  
Ultrahigh Pressure ◽  
Phonon Modes ◽  
Interband Coupling

AbstractThe recent report of superconductivity under high pressure at the record transition temperature of Tc =203 K in pressurized H2S has been identified as conventional in view of the observation of an isotope effect upon deuteration. Here it is demonstrated that conventional theories of superconductivity in the sense of BCS or Eliashberg formalisms cannot account for the pressure dependence of the isotope coefficient. The only way out of the dilemma is a multi-band approach of superconductivity where already small interband coupling suffices to achieve the high values of Tc together with the anomalous pressure dependent isotope coefficient. In addition, it is shown that anharmonicity of the hydrogen bonds vanishes under pressure whereas anharmonic phonon modes related to sulfur are still active.

Photolyse de l'isoprène gazeux entre son seuil d'absorption (ca. 255 nm) et 147.0 nm

1978 ◽  
Vol 56 (14) ◽  
pp. 1864-1870 ◽  
Author(s):  
Rosaire Demers ◽  
Guy J. Collin ◽  
H. Gagnon-Deslauriers
Keyword(s):  
High Pressure ◽  
Pressure Dependence ◽  
Lower Energy ◽  
Main Product ◽  
Pressure Effect

We studied the photolysis of isoprene at wavelengths between the absorption threshold (ca. 255 nm) and 147.0 nm. The pressure effect was studied between 30 and 2660 N m−2. At the lower energy, light products are formed and their yields decrease with an increase in the pressure. From Stern–Volmer plots, we have concluded that the photoexcited molecule is collision stabilized at high pressure. Less pressure dependence was observed at 174 and at 163.3 nm. At these energies, and at 147 nm, all of the photoexcited molecules decompose. At 147 nm, no pressure effect was observed, and the main product is vinylacetylene (Ф = 0.66). The formation of this product was explained on the basis of the CH3—C4H5 split followed by the fragmentation of the excited C4H5* radicals. At 174 nm, this last radical is collisionally stabilized. Finally we have measured the ratio k(CH3 + H2S)/k(CH3 + isoprene) = k1/k12 and k1/k12 = 41 + 3

Sign in / Sign up

Export Citation Format

Share Document