Deuterium Measurements Research Articles

Solution and Gas-Phase H/D Exchange of Protein–Small-Molecule Complexes: Cex and Its Inhibitors

The properties of noncovalent complexes of the enzyme exo-1,4-β-D-glycanase ("Cex") with three aza-sugar inhibitors, deoxynojirimycin (X(2)DNJ), isofagomine lactam (X(2)IL), and isofagomine (X(2)IF), have been studied with solution and gas-phase hydrogen deuterium exchange (H/Dx) and measurements of collision cross sections of gas-phase ions. In solution, complexes have lower H/Dx levels than free Cex because binding the inhibitors blocks some sites from H/Dx and reduces fluctuations of the protein. In mass spectra of complexes, abundant Cex ions are seen, which mostly are formed by dissociation of complexes in the ion sampling interface. Both complex ions and Cex ions formed from a solution containing complexes have lower cross sections than Cex ions from a solution of Cex alone. This suggests the Cex ions formed by dissociation "remember" their solution conformations. For a given charge, ions of the complexes have greater gas-phase H/Dx levels than ions of Cex. Unlike cross sections, H/Dx levels of the complexes do not correlate with the relative gas-phase binding strengths measured by MS/MS. Cex ions from solutions with or without inhibitors, which have different cross sections, show the same H/Dx level after 15 s, indicating the ions may fold or unfold on the seconds time scale of the H/Dx experiment. Thus, cross sections show that complexes have more compact conformations than free protein ions on the time scale of ca. 1 ms. The gas-phase H/Dx measurements show that at least some complexes retain different conformations from the Cex ions on a time scale of seconds.

Overview of JT-60U results towards the resolution of key physics and engineering issues in ITER and JT-60SA

This paper presents an overview of recent results from JT-60U. Topics we particularly focus on are (1) the mechanism determining the rotation profile and the effect of rotation on/from transport and stability, (2) the edge localized mode (ELM) physics and active ELM control and (3) plasma–wall interactions. An analysis of the momentum transport showed that rotation with a high pressure gradient can be reproduced by introducing a residual stress term proportional to the momentum diffusivity and the pressure gradient. Also, the momentum diffusivity in an internal transport barrier (ITB) region was reduced to an order similar to that of the ion thermal diffusivity. A comparison of the edge pedestal characteristics between JT-60U and JET with matched shape and operational parameters showed that the edge pressure did not change with increasing toroidal field (TF) ripple up to 1%, whereas a linear shift of the rotation velocity to the counter-direction was observed with increasing TF ripple. The absolute evaluation of tungsten accumulation in the core plasma by a spectroscopic method clarified that tungsten accumulation increased with increasing toroidal rotation in the counter-direction while an H-mode was sustained even at a tungsten density of 10−3 times the electron density. Active control of neoclassical tearing mode (NTM) islands by the electron cyclotron current drive showed that the growth of NTM islands decelerated the plasma rotation. A transition to a low-rotation frequency state occurred for larger NTM islands. A statistical analysis of the precursor of type I ELM showed a small growth rate of γ/ωA ∼ 10−3 (where γ and ωA are the growth rate and Alfvén angular frequency, respectively). The measurement of the precursor at different toroidal locations showed that the toroidal mode number was 8–10 or 14–16. Energetic-particle-driven wall modes (EWMs) were found to trigger ELMs and decrease the ELM amplitude to half of that without EWMs. Enhancement of the ELM frequency by electron cyclotron heating in the edge region of the high-field side was observed, and the frequency increase was four times than that of neutral beam injection cases having the same absorption power. Laser scattering measurement of carbon dust generation showed that the dust distribution had a peak in the far scrape-off layer and penetration into the core plasma was not significant. Depth profile measurements of deuterium and carbon in tungsten-coated tiles (tungsten thickness: 50 µm) determined that the ratio of deuterium to carbon was 0.06 ± 0.02 over a 20 µm depth, suggesting deuterium trapping by carbon in the tungsten layer. Furthermore, new records for both the beam energy of negative-ion-based neutral beams (507 keV) and the output power of 110 GHz electron cyclotron waves (1.5 MW for 4 s from one gyrotron) were achieved, which confirmed and extended the heating and current drive capabilities of ITER and JT-60SA.

Distinct Purine Distribution in Carbonaceous Chondrites

Carbonaceous chondrite meteorites are known to contain a diverse suite of organic compounds, many of which are essential components of biochemistry. Amino acids, which are the monomers of proteins, have been extensively studied in such meteorites (e.g. Botta and Bada 2002; Pizzarello et aI., 2006). The origin of amino acids in meteorites has been firmly established as extraterrestrial based on their detection typically as racemic mixtures of amino acids, the presence of many non-protein amino acids, and non-terrestrial values for compound-specific deuterium, carbon, and nitrogen isotopic measurements. In contrast to amino acids, nucleobases in meteorites have been far less studied. Nucleobases are substituted one-ring (pyrimidine) or two-ring (purine) nitrogen heterocyclic compounds and serve as the information carriers of nucleic acids and in numerous coenzymes. All of the purines (adenine, guanine, hypoxanthine, and xanthine) and pyrimidines (uracil) previously reported in meteorites are biologically common and could be interpreted as the result of terrestrial contamination (e.g. van del' Velden and Schwartz, 1974.) Unlike other meteoritic organics, there have been no observations of stochastic molecular diversity of purines and pyrimidines in meteorites, which has been a criterion for establishing extraterrestrial origin. Maltins et al. (2008) performed compound-specific stable carbon isotope measurements for uracil and xanthine in the Murchison meteorite. They assigned a non-terrestrial origin for these nucleobases; however, the possibility that interfering indigenous molecules (e.g. carboxylic acids) contributed to the 13C-enriched isotope values for these nucleobases cannot be completely ruled out. Thus, the origin of these meteoritic nucleobases has never been established unequivocally. Here we report on our investigation of extracts of II different carbonaceous chondrites covering various petrographic types (Cl, CM, and CR) and degrees of aqueous alteration (l, 2, and 3) and one ureilite. Analysis via liquid chromatography coupled with electrospray triple-stage mass spectrometry or orbitrap mass spectrometry employed a targeted approach for analysis focused on the five canonical RNA/DNA nucleobases as well as 14 non-canonical pyrimidines and purines, which have bcen observed under plausible prebiotic reactions.

Links between MIS 11 millennial to sub-millennial climate variability and long term trends as revealed by new high resolution EPICA Dome C deuterium data – A comparison with the Holocene

Abstract. We expand here the description of the Antarctic temperature variability during the long interglacial period occurring ~400 thousand years before the present (Marine Isotopic Stage, MIS 11). Our study is based on new detailed deuterium measurements conducted on the EPICA Dome C ice core, Antarctica, with a ~50 year temporal resolution. Despite an ice diffusion of a length reaching ~8 cm at MIS 11 depth, the data allow us to highlight a variability at multi-centennial scale for MIS 11, as it has already been observed for the Holocene period (MIS 1). The differences between MIS 1 and MIS 11 are analysed regarding the links between multi-millennial trends and sub-millennial variability. The EPICA Dome C deuterium record shows an increased variability and the onset of millennial to sub-millennial periodicities at the beginning of the final cooling phase of MIS 11. Our findings are robust with respect to sensitivity tests on the somewhat uncertain MIS 11 duration.

Measured deuterium in water vapour concentration does not improve the constraint on the partitioning of evapotranspiration in a tall forest canopy, as estimated using a soil vegetation atmosphere transfer model

Partitioning the evapotanspiration ( ET) flux in a forest into its component fluxes is important for understanding the water and carbon budgets of the ecosystem. We use non-linear parameter estimation to determine the vertical profile of the Lagrangian timescale ( T L ) and partitioning of ET that simultaneously optimise agreement between modelled and measured vertical profiles of temperature, water vapour, carbon dioxide concentrations, and deuterated water vapour for a two-week period in November 2006. High precision real-time trace gas measurements were obtained by FTIR spectroscopy. Modelled temperature and concentration profiles are generated using a Lagrangian dispersion theory combined with source/sink distributions of HDO, H 2O, sensible heat, and CO 2. These distributions are derived from an isotopically enabled multilayer Soil Vegetation Atmospheric Transfer (SVAT) model subject to multiple constraints. The soil component of the model was tested in isolation using measured deuterium content of soil chamber evaporate, while the leaf component was tested using isotopic analyses of leaf and xylem water, combined with leaf-level gas exchange measurements. Optimisation of T L and the partition of ET was performed twice: once using only temperature, H 2O and CO 2 profiles and a second time including HDO as well. The modelled vertical concentration profiles resulting from inclusion of HDO in the cost function demonstrate our ability to make consistent estimates of both the scalar source distributions and the deuterium content of the water vapour sources. However, introducing measurements of deuterium in water vapour does not significantly alter resulting estimates of normalised T L (0.4 ± 0.1 at canopy top) and the partition of ET (85 ± 2% transpiration), suggesting that the additional data and modelling required to use deuterium are not warranted for the purpose of partitioning ET using the framework presented here.

Small-angle neutron scattering measurements of hydrogen and deuterium trapping at dislocations in deformed single-crystalline Pd at low temperature

Small-angle neutron scattering (SANS) measurements of hydrogen and deuterium trapped at dislocation defects in deformed single-crystalline Pd have been performed at 15, 100, and 200 K at total interstitial solute concentrations of order ${10}^{\ensuremath{-}3}$. This work supports recent incoherent inelastic neutron scattering measurements of the vibrational density of states of trapped hydrogen under similar concentration-temperature conditions [Heuser et al., Phys. Rev. B 78, 214101 (2008)]. The measured net absolute macroscopic differential scattering cross sections have been fitted with a cylindrical form factor representing solute-decorated dislocation line segments. Generally, very little difference in the measured cross sections was observed with temperature for a given solute type, while a significant change was observed between hydrogen- and deuterium-loaded samples. The latter difference is understood within a cross-section model that takes into account the local lattice dilatation associated with solute segregation at dislocations. The application of the model cross section to the net PdH${}_{0.0013}$ SANS response yields an effective trapping radius of $R$ \ensuremath{\sim} 10 \AA{} and dislocation density of ${\ensuremath{\rho}}_{d}~{10}^{10}$ cm${}^{\ensuremath{-}2}$. Analysis of the SANS response allowed the local trapped solute concentration (\ensuremath{\sim}0.5 [H]/[Pd]) and volumetric dilatation (\ensuremath{\Delta}\ensuremath{\nu}/\ensuremath{\Omega} \ensuremath{\sim} 1.1) to be determined with the constraint that the system locally satisfies the known lattice expansion of Pd hydride (i.e., Vegard's law).

KAONIC HELIUM MEASUREMENTS IN THE SIDDHARTA EXPERIMENT

The SIDDHARTA experiment (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) had the aim to perform kaonic atoms X-ray transitions measurements, to better understand aspects of the low-energy QCD in the strangeness sector. The experiment combined the excellent low-energy kaon beam generated at DAΦNE, allowing to use gaseous targets, with excellent fast X-rays detectors: Silicon Drift Detectors. SIDDHARTA was installed on DAΦNE in autumn 2008 and took data till late 2009. Apart of the kaonic hydrogen and kaonic deuterium measurements, we have performed the kaonic helium transitions to the 2p level ( L -lines) measurements: for the first time in a gaseous target for helium4 and for the first time ever for kaonic helium3. The interest for such type of measurement was rather high, being it triggered by two reasons: the so-called "kaonic helium puzzle" (even if this was solved by KEK-PS E570 experiment, but a cross-check was useful) and some theoretical predictions of possible high energy shift (at the level of 10 eV). In this paper the preliminary results for the measurements to the 2p level ( L -series) for kaonic helium4 and kaonic helium3 are presented.

Kaon-nucleon/nuclei interaction studies by kaonic atoms measurements: the SIDDHARTA experiment at DAΦNE

The SIDDHARTA experiment (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) had the aim to perform a precise measurement of K-series kaonic hydrogen x-rays and the first-ever measurement of the kaonic deuterium x-rays to determine the strong-interaction energy-level shifts and widths of the lowest lying atomic states. These measurements offer a unique possibility to precisely determine the isospin-dependent kaon-nucleon(KN) scattering lengths which are directly connected with the physics of the KN interaction. The experiment combined the excellent low-energy kaon beam generated at DAΦNE, allowing to use gaseous targets, with excellent fast X-rays detectors: Silicon Drift Detectors. SIDDHARTA was installed on DAΦNE in autumn 2008 and took data till late 2009. Apart of the kaonic hydrogen and kaonic deuterium measurements, we have performed the kaonic helium transitions to the 2 p level (L-lines) measurements: for the first time in a gaseous target for kaonic helium 4 and for the first time ever for kaonic helium 3. In this paper, an overview of this experiment and preliminary results are presented, together with future plans.

Investigating Inner-Sphere Reorganization via Secondary Kinetic Isotope Effects in the C−H Cleavage Reaction Catalyzed by Soybean Lipoxygenase: Tunneling in the Substrate Backbone as Well as the Transferred Hydrogen

This work describes the application of NMR to the measurement of secondary deuterium (2° (2)H) and carbon-13 ((13)C) kinetic isotope effects (KIEs) at positions 9-13 within the substrate linoleic acid (LA) of soybean lipoxygenase-1. The KIEs have been measured using LA labeled with either protium (11,11-h2-LA) or deuterium (11,11-d2-LA) at the reactive C11 position, which has been previously shown to yield a primary deuterium isotope effect of ca. 80. The conditions of measurement yield the intrinsic 2° (2)H and (13)C KIEs on k(cat)/K(m) directly for 11,11-d2-LA, whereas the values for the 2° (2)H KIEs for 11,11-h2-LA are obtained after correction for a kinetic commitment. The pattern of the resulting 2° (2)H and (13)C isotope effects reveals values that lie far above those predicted from changes in local force constants. Additionally, many of the experimental values cannot be modeled by electronic effects, torsional strain, or the simple inclusion of a tunneling correction to the rate. Although previous studies have shown the importance of extensive tunneling for cleavage of the primary hydrogen at C11 of LA, the present findings can only be interpreted by extending the conclusion of nonclassical behavior to the secondary hydrogens and carbons that flank the position undergoing C-H bond cleavage. A quantum mechanical method introduced by Buhks et al. [J. Phys. Chem. 1981, 85, 3763] to model the inner-sphere reorganization that accompanies electron transfer has been shown to be able to reproduce the scale of the 2° (2)H KIEs.

Kaon-nucleon strong interaction in kaonic atoms

The SIDDHARTA experiment (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) aims to perform a precise measurement of the X-ray K-series of kaonic hydrogen and the first-ever measurement of kaonic deuterium, to obtain the strong-interaction energy-level shifts and widths of the lowest lying atomic states. The measurements will allow the determination of the isospin-dependent kaon-nucleon (KN) scattering lengths, directly connected to the physics of the KN interaction. The experiment uses the low-energy kaon beam generated at DAΦNE collider, high-density cryogenic targets and fast, large area X-ray spectroscopic detectors. In addition to the kaonic hydrogen and kaonic deuterium, the collaboration performed measurements of the kaonic Helium transitions to the 2p level (L-lines). Kaonic Helium 4 was measured for the first time in a gaseous target while the kaonic Helium 3 was mesured for the first time ever.

Electroweak Nuclear Response in the Quasielastic Regime

The availability of the double-differential charged-current neutrino cross section, measured by the MiniBooNE Collaboration by using a carbon target, allows for a systematic comparison of nuclear effects in quasielastic electron and neutrino scattering. The results of our study, based on the impulse approximation scheme and a state-of-the-art model of the nuclear spectral functions, suggest that the electron cross section and the flux averaged neutrino cross sections, corresponding to the same target and comparable kinematical conditions, cannot be described within the same theoretical approach using the value of the nucleon axial mass obtained from deuterium measurements. We analyze the assumptions underlying the treatment of electron-scattering data and argue that the description of neutrino data will require a new paradigm, suitable for application to processes in which the lepton kinematics is not fully determined.

New MIS 19 EPICA Dome C high resolution deuterium data: Hints for a problematic preservation of climate variability at sub-millennial scale in the “oldest ice”

Marine Isotope Stage 19 (MIS 19) is the oldest interglacial period archived in the EPICA Dome C ice core (~ 780 ky BP) and the closest “orbital analogue” to the Holocene — albeit with a different obliquity amplitude and phase with precession. New detailed deuterium measurements have been conducted with a depth resolution of 11 cm (corresponding time resolution of ~ 130 years). They confirm our earlier low resolution profile (55 cm), showing a relatively smooth shape over the MIS 20 to MIS 18 time period with a lack of sub-millennial climate variability, first thought to be due to this low resolution. The MIS 19 high resolution profile actually reveals a strong isotopic diffusion process leading to a diffusion length of at least ~ 40 cm erasing sub-millennial climate variability. We suggest that this diffusion is caused by water-veins associated with large ice crystals at temperatures above −10 °C, temperature conditions in which the MIS 19 ice has spent more than 200 ky. This result has implications for the selection of the future “oldest ice” drilling site.

Measurements of deuterium in the Milky Way

AbstractIn this article I review measurements of deuterium in the Milky Way.

Metabolic precursors of surfactant disaturated-phosphatidylcholine in preterms with respiratory distress

Our objective was to study the metabolic precursors of surfactant disaturated-phosphatidylcholine (DSPC) in preterm infants with respiratory distress syndrome (RDS) on mechanical ventilation. We performed 46 DSPC kinetic studies in 23 preterms on fat-free parenteral nutrition and mechanical ventilation (birth weight = 1167 +/- 451 g, gestational age = 28.5 +/- 2.0 weeks). Eight infants received a simultaneous intravenous infusion of U(13)C-glucose and [16,16,16](2)H-palmitate, eight infants received U(13)C-glucose and (2)H(2)O, and seven received U(13)C-palmitate and (2)H(2)O. Surfactant DSPC kinetics were calculated from the isotopic enrichments of DSPC-palmitate from sequential tracheal aspirates and its metabolic precursors in plasma or urine. DSPC fractional synthesis rate (FSR) was 17 +/- 11, 21 +/- 16, and 15 +/- 6%/day from glucose, palmitate, and body water, respectively (P = 0.36). DSPC-FSR from U(13)C-glucose and (2)H(2)O were significantly correlated and yielded similar estimates (difference of -0.1 +/- 3%) (P = 0.91). The difference in the 15 infants receiving palmitate versus (2)H(2)O or palmitate versus glucose was +6.0 +/- 12%/day (P = 0.21). There was a significant correlation between DSPC-FSRs from plasma glucose and plasma FFA. The contribution of glucose versus palmitate to DSPC-FSR was 49 +/- 20% versus 51 +/- 20%, respectively. Plasma glucose and FFA showed similar contributions to DSPC-FSR in infants with RDS and fat-free parenteral nutrition. FSRs from (2)H(2)O or glucose were highly correlated.

Surrogate H/D Detection Strategy for Protein Conformational Analysis Using MS/MS Data

Amide hydrogen/deuterium exchange (H/DX) measurements by mass spectrometry provide a powerful tool for probing the structure and dynamics of proteins. In order to extend such measurements to complex multiprotein systems, new methods for delivering higher sensitivity and sequence coverage are required. In this study, we investigated the utility of tandem mass spectrometry (MS/MS) for providing an alternative to the conventional MS mode of operation applied to bottom-up H/DX experiments. Specifically, we aimed to determine whether differential deuteration measurements of collisionally induced dissociation (CID)-generated product ions can serve as effective surrogates for their corresponding intact peptide, thus providing an additional dimension for analysis. Replicate deuterium measurements of calmodulin (in its apo and holo forms) were obtained from peptic digests in both the MS and MS/MS domains and studied as a function of % deuteration, fragment ion selection, and contaminant level. We show that successful acquisition of MS/MS data for deuterated peptides requires controlled expansion of the isotopic envelope by limiting the range of deuterium label applied in the exchange-in reaction (< or = 50%) and that automation of ion selection via data-dependent acquisition is ultimately dependent upon peak detection algorithms. Upon full transmission of the isotopic envelope, fragment data demonstrate that all ions, with the exception of neutral loss fragment ions, return deuteration ratios reflecting the apo/holo transition that are in general agreement with values obtained from the corresponding precursor ions. The agreement is limited primarily by the ion statistics for each fragment, as the base peak in the MS/MS spectra provided the best correlation regardless of its m/z. We highlight that the freedom to select the base peak as a surrogate for the precursor ion derives from extensive H/D scrambling inducible under conventional CID conditions. When spectral interference prohibits conventional H/DX-MS measurements, we further show that the surrogate approach recovers accurate and precise per-peptide deuteration levels. Thus, a generalized strategy is presented in which CID-based automated H/DX-MS/MS acquisition can be used to extend measurements to complex protein systems, exceeding the peptide capacity of conventional H/DX-MS alone.

New X-Ray Detectors for Exotic Atom Research

Hadronic atoms being Coulomb-bound systems in which the electron is substituted by a hadron like a negatively charged K meson are perfect probes for the study of strong interaction at lowest energies using x-ray spectroscopy. New large area x-ray detectors (silicon drift detectors, SDDs) were developed to provide excellent energy resolution as well as timing capability. For the first time large area SDDs were employed to measure the L-lines of kaonic helium at high precision thus succeeding in clarifying a puzzle persisting for 30 years since the 70's. An array of about 200 even more sophisticated SDDs (1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> SDDs with monolithically integrated FET) will be used to perform precision measurements (i.e., at the eV level) of kaonic hydrogen and kaonic deuterium at the DAFNE Phi factory of LNF/Italy. The new x-ray detectors and their performance for precision experiments in the accelerator environment are presented.

Galactose oxidase as a model for reactivity at a copper superoxide center.

The mononuclear copper enzyme, galactose oxidase, has been investigated under steady-state conditions via O(2)-consumption assays using 1-O-methyl-alpha-D-galactopyranoside as the sugar substrate to produce an aldehyde at the C-6 position. The rate-determining step of the oxidative half-reaction was probed through the measurement of substrate and solvent deuterium and O-18 isotope effects on k(cat)/K(m)(O(2)). The reaction conforms to a ping-pong mechanism with the kinetic parameters for the reductive half, k(cat)/K(m)(S) = 8.3 x 10(3) M(-1) s(-1) at 10 degrees C and pH 7.0, comparing favorably to literature values. The oxidative half-reaction yielded a value of k(cat)/K(m)(O(2)) = 2.5 x 10(6) M(-1) s(-1). A substrate deuterium isotope effect of 32 was measured for the k(cat)/K(m)(S), while a smaller, but significant value of 1.6-1.9 was observed on k(cat)/K(m)(O(2)). O-18 isotope effects of 1.0185 with either protiated or deuterated sugar, together with the absence of any solvent isotope effect, lead to the conclusion that hydrogen atom transfer from reduced cofactor to a Cu(II)-superoxo intermediate is fully rate-determining for k(cat)/K(m)(O(2)). The measured O-18 isotope effects provide corroborative evidence for the reactive superoxo species in the dopamine beta-monooxygenase/peptidylglycine alpha-hydroxylating monooxygenase family, as well as providing a frame of reference for copper-superoxo reactivity. The combination of solvent and substrate deuterium isotope effects rules out solvent deuterium exchange into reduced enzyme as the origin of the relatively small substrate deuterium isotope effect on k(cat)/K(m)(O(2)). These data indicate fundamental differences in the hydrogen transfer step from the carbon of substrate vs the oxygen of reduced cofactor during the reductive and oxidative half-reactions of galactose oxidase.

Deuterium Measurements of Raptor Feathers: Does a Lack of Reproducibility Compromise Geographic Assignment?

Abstract.— Despite the widespread use of stable isotopes in studies of avian movement, key assumptions on which the methodology is based remain unsubstantiated, including the assumption that measurements of stable hydrogen isotopes in feathers (δDf) are consistent across time within the same laboratory or among laboratories using the same analytical protocols and keratin standards. We tested this assumption by remeasuring δDf from 211 raptor feathers within and between laboratories. Initial and repeat samples were prepared and analyzed using identical protocols but analyzed in distinct automated runs with laboratory staff blind to sample identity. Reproducibility of δDf measurements varied significantly and substantially among nine independent sample groups. Feather δD measurements among sample groups exhibited average isotopic shifts from -15.6%‰ to +27.5%‰ (an absolute difference of 43.1%‰), with standard deviations from 6.0%‰ to 12.4%‰. Therefore, despite existing analytical protocols to address issues...

The trapping behavior of deuterium in F82H ferritic/martensitic steel

In the present work, the trapping behavior of deuterium in F82H under irradiation were studied by means of thermal desorption spectrometry (TDS) and TEM. The specimens were first irradiated with 5 keV He + at 600 °C followed by the additional D 2 + irradiations with the energy of 0.5 keV at RT. Some of the specimens were also irradiated with relatively higher energy of 1 MeV for He + and 650 keV for D 2 + ions. According to thermal desorption measurements of deuterium and helium after irradiations, deuterium desorption peak shift to higher temperatures of about 30 K were observed for the case with helium irradiations, which attributed to the deuterium trapped by a surroundings of the helium bubbles. In addition, it is also concluded from the thermal desorption measurements of deuterium on re-tempered and as-received specimens without helium irradiations that the latently existing carbides can acts as a potential trapping site for deuterium in F82H.

Time-resolved optical spectroscopy measurements of shocked liquid deuterium

Time-resolved optical spectroscopy has been used to measure the shock pressure steadiness, emissivity, and temperature of liquid deuterium shocked to 22--90 GPa. The shock was produced using magnetically accelerated flyer plate impact, and spectra were acquired with a suite of four fiber-optic-coupled spectrometers with streak camera detectors. The shock pressure changes by an average of $\ensuremath{-}1.2%$ over the 10--30 ns cell transit time, determined from the relative changes in the shock front self-emission with time. The shock front reflectivity was measured from $5140\text{ }\text{\AA{}}$ and $5320\text{ }\text{\AA{}}$ laser light reflected from the ${D}_{2}$ shock. The emissivity inferred from the reflectivity measurements was in reasonably good agreement with quantum molecular dynamics simulation predictions. The spectral radiance wavelength dependence was found to agree well (average normalized ${\ensuremath{\chi}}^{2}=1.6$) with a Planckian multiplied by the emissivity. The shock front temperature was determined from the emissivity and the wavelength-dependent shock self-emission. Thirty-seven temperature measurements spanning the 22--90 GPa range were accumulated. The large number of temperature measurements enables a comparison of the scatter in the data with expectations for a Gaussian distribution. This facilitates determination of uncertainties that incorporate both apparatus contributions and otherwise unquantified systematic effects that cause self-emission variations from one experiment to another. Agreement between temperatures determined from the absolute spectral radiance and from the relative shape of the spectrum further substantiates the absence of systematic biases. The weighted mean temperature uncertainties were as low as $\ifmmode\pm\else\textpm\fi{}3--4%$, enabling the discrimination between competing models for the ${D}_{2}$ equation of state (EOS). The temperature results agree well with models that predict a maximum compression of $\ensuremath{\sim}4.4$. Softer models that predict approximately sixfold compression are inconsistent with the data to a very high statistical confidence level. Previous analysis [D. Saumon and T. Guillot, Astrophys. J. 609, 1170 (2004)] of Jupiter's internal structure has shown that the core mass is restricted to be less than approximately three times the mass of the Earth, if EOS models consistent with these temperature measurements are employed.