ALCHEMI: an ALMA Comprehensive High-resolution Extragalactic Molecular Inventory. Survey presentation and first results from the ACA array

Phase contrast TEM has been the leading technique for high resolution imaging of materials for many years, whilst STEM has been the principal method for high-resolution microanalysis. However, it was demonstrated many years ago that low angle dark-field STEM imaging is a priori capable of almost 50% higher point resolution than coherent bright-field imaging (i.e. phase contrast TEM or STEM). This advantage was not exploited until Pennycook developed the high-angle annular dark-field (ADF) technique which can provide an incoherent image showing both high image resolution and atomic number contrast.This paper describes the design and first results of a 300kV field-emission STEM (VG Microscopes HB603U) which has improved ADF STEM image resolution towards the 1 angstrom target. The instrument uses a cold field-emission gun, generating a 300 kV beam of up to 1 μA from an 11-stage accelerator. The beam is focussed on to the specimen by two condensers and a condenser-objective lens with a spherical aberration coefficient of 1.0 mm.

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Imaging of polymer single crystals in low-voltage, high-resolution scanning electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178665 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1106-1107

Author(s):

W.W. Adams ◽

G. Price ◽

A. Krause

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

High Resolution ◽

Single Crystals ◽

Low Voltage ◽

Polymer Surface ◽

Beam Current ◽

Image Features ◽

First Results ◽

Scanning Electron

It has been shown that there are numerous advantages in imaging both coated and uncoated polymers in scanning electron microscopy (SEM) at low voltages (LV) from 0.5 to 2.0 keV compared to imaging at conventional voltages of 10 to 20 keV. The disadvantages of LVSEM of degraded resolution and decreased beam current have been overcome with the new generation of field emission gun SEMs. In imaging metal coated polymers in LVSEM beam damage is reduced, contrast is improved, and charging from irregularly shaped features (which may be unevenly coated) is reduced or eliminated. Imaging uncoated polymers in LVSEM allows direct observation of the surface with little or no charging and with no alterations of surface features from the metal coating process required for higher voltage imaging. This is particularly important for high resolution (HR) studies of polymers where it is desired to image features 1 to 10 nm in size. Metal sputter coating techniques produce a 10 - 20 nm film that has its own texture which can obscure topographical features of the original polymer surface. In examining thin, uncoated insulating samples on a conducting substrate at low voltages the effect of sample-beam interactions on image formation and resolution will differ significantly from the effect at higher accelerating voltages. We discuss here sample-beam interactions in single crystals on conducting substrates at low voltages and also present the first results on HRSEM of single crystal morphologies which show some of these effects.

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Cryogenic vitrification and 3D serial sectioning using high resolution cryo-FIB SEM technology for brine-filled grain boundaries in halite: first results

Geofluids ◽

10.1111/j.1468-8123.2007.00205.x ◽

2008 ◽

Vol 8 (1) ◽

pp. 60-72 ◽

Cited By ~ 41

Author(s):

G. DESBOIS ◽

J. L. URAI ◽

C. BURKHARDT ◽

M. R. DRURY ◽

M. HAYLES ◽

...

Keyword(s):

High Resolution ◽

Grain Boundaries ◽

Serial Sectioning ◽

First Results

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Masses and ages for metal-poor stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834081 ◽

2019 ◽

Vol 627 ◽

pp. A173 ◽

Cited By ~ 4

Author(s):

M. Valentini ◽

C. Chiappini ◽

D. Bossini ◽

A. Miglio ◽

G. R. Davies ◽

...

Keyword(s):

High Resolution ◽

Seismic Data ◽

Age Determination ◽

High Resolution Spectroscopy ◽

Chemical Abundances ◽

Abundance Pattern ◽

Halo Stars ◽

Stellar Ages ◽

First Results ◽

Detailed Chemical

Context. Very metal-poor halo stars are the best candidates for being among the oldest objects in our Galaxy. Samples of halo stars with age determination and detailed chemical composition measurements provide key information for constraining the nature of the first stellar generations and the nucleosynthesis in the metal-poor regime. Aims. Age estimates are very uncertain and are available for only a small number of metal-poor stars. We present the first results of a pilot programme aimed at deriving precise masses, ages, and chemical abundances for metal-poor halo giants using asteroseismology and high-resolution spectroscopy. Methods. We obtained high-resolution UVES spectra for four metal-poor RAVE stars observed by the K2 satellite. Seismic data obtained from K2 light curves helped improve spectroscopic temperatures, metallicities, and individual chemical abundances. Mass and ages were derived using the code PARAM, investigating the effects of different assumptions (e.g. mass loss and [α/Fe]-enhancement). Orbits were computed using Gaia DR2 data. Results. The stars are found to be normal metal-poor halo stars (i.e. non C-enhanced), and an abundance pattern typical of old stars (i.e. α and Eu-enhanced), and have masses in the 0.80−1.0 M⊙ range. The inferred model-dependent stellar ages are found to range from 7.4 Gyr to 13.0 Gyr with uncertainties of ∼30%−35%. We also provide revised masses and ages for metal-poor stars with Kepler seismic data from the APOGEE survey and a set of M4 stars. Conclusions. The present work shows that the combination of asteroseismology and high-resolution spectroscopy provides precise ages in the metal-poor regime. Most of the stars analysed in the present work (covering the metallicity range of [Fe/H] ∼ −0.8 to −2 dex) are very old >9 Gyr (14 out of 19 stars), and all of the stars are older than >5 Gyr (within the 68 percentile confidence level).

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Multi-Wavelength High-Resolution Spectroscopy for Exoplanet Detection: Motivation, Instrumentation and First Results

Geosciences ◽

10.3390/geosciences8080289 ◽

2018 ◽

Vol 8 (8) ◽

pp. 289 ◽

Cited By ~ 1

Author(s):

Serena Benatti

Keyword(s):

High Resolution ◽

Near Infrared ◽

Giant Planet ◽

High Resolution Spectroscopy ◽

M Dwarfs ◽

Low Mass Stars ◽

First Results ◽

Multi Wavelength ◽

Low Mass ◽

Rocky Planets

Exoplanet research has shown an incessant growth since the first claim of a hot giant planet around a solar-like star in the mid-1990s. Today, the new facilities are working to spot the first habitable rocky planets around low-mass stars as a forerunner for the detection of the long-awaited Sun-Earth analog system. All the achievements in this field would not have been possible without the constant development of the technology and of new methods to detect more and more challenging planets. After the consolidation of a top-level instrumentation for high-resolution spectroscopy in the visible wavelength range, a huge effort is now dedicated to reaching the same precision and accuracy in the near-infrared. Actually, observations in this range present several advantages in the search for exoplanets around M dwarfs, known to be the most favorable targets to detect possible habitable planets. They are also characterized by intense stellar activity, which hampers planet detection, but its impact on the radial velocity modulation is mitigated in the infrared. Simultaneous observations in the visible and near-infrared ranges appear to be an even more powerful technique since they provide combined and complementary information, also useful for many other exoplanetary science cases.

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UTE‐SENCEFUL: first results for 3D high‐resolution lung ventilation imaging

Magnetic Resonance in Medicine ◽

10.1002/mrm.27576 ◽

2018 ◽

Vol 81 (4) ◽

pp. 2464-2473 ◽

Cited By ~ 10

Author(s):

L. Mendes Pereira ◽

T. Wech ◽

A.M. Weng ◽

C. Kestler ◽

S. Veldhoen ◽

...

Keyword(s):

High Resolution ◽

Lung Ventilation ◽

Ventilation Imaging ◽

First Results ◽

Lung Ventilation Imaging

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ACTIVE TARGET AS A TOOL FOR NUCLEAR SPECTROSCOPY AND REACTIONS

International Journal of Modern Physics E ◽

10.1142/s0218301309014159 ◽

2009 ◽

Vol 18 (10) ◽

pp. 1997-2002

Author(s):

◽

PATRICIA ROUSSEL-CHOMAZ ◽

HERVE SAVAJOLS

Keyword(s):

High Resolution ◽

Time Projection Chamber ◽

First Generation ◽

Rare Events ◽

Nuclear Spectroscopy ◽

Next Generation ◽

Active Target ◽

First Results ◽

Time Projection

By the very nature of secondary beams, their intensity is limited, particularly for beams of the highest interest - farthest away from stability. Active targets, which can be described as time projection chamber (TPC)-like detectors in which the detector gas is the target, have been shown to have the highest sensitivity for quantitative high resolution studies of rare events. The physics cases that can be addressed with these devices are reviewed and some of the first results obtained with first generation active targets are detailed. Finally some general ideas on the next generation of active targets are presented.

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Decadal changes in the Atlantic Meridional Overturning Circulation in high-resolution simulations of the subpolar North Atlantic

10.5194/egusphere-egu21-7789 ◽

2021 ◽

Author(s):

Claus W. Böning ◽

Arne Biastoch ◽

Klaus Getzlaff ◽

Patrick Wagner ◽

Siren Rühs ◽

...

Keyword(s):

High Resolution ◽

North Atlantic ◽

Deep Convection ◽

Alternative Interpretation ◽

Meridional Overturning Circulation ◽

Global Ocean ◽

Labrador Sea ◽

Overturning Circulation ◽

First Results ◽

Meridional Overturning

A series of global ocean - sea ice model simulations is used to investigate the spatial structure and temporal variability of the sinking branch of the meridional overturning circulation (AMOC) in the subpolar North Atlantic. The experiments include hindcast simulations of the last six decades based on the high-resolution (1/20&#176;) VIKING20X-model forced by the CORE and JRA55-do reanalysis products, supplemented by sensitivity studies with a 1/4&#176;-configuration (ORCA025) aimed at elucidating the roles of variations in the wind stress and buoyancy fluxes. The experiments exhibit different multi-decadal trends in the AMOC, reflecting the well-known sensitivity of ocean-only models to subtle details in the configuration of the subarctic freshwater forcing. All experiments, however, concur in that the dense, southward branch of the overturning is mainly fed by &#8220;sinking&#8221; (in density space) in the Irminger and Iceland Basins, in accordance with the first results of the OSNAP observational program. Remarkably, the contribution of the Labrador Sea has remained small throughout the whole simulation period, even during the phase of extremely strong convection in the early 1990s: i.e., the rate of deep water exported from the subpolar North Atlantic by the DWBC off Newfoundland never differed by more than O(1 Sv) from the DWBC entering the Labrador Sea at Cape Farewell. The model solutions indicate a particular concentration of the sinking along the deep boundary currents south of the Denmark Straits and south of Iceland, pointing to a prime importance for the AMOC of the outflows from the Nordic Seas and their subsequent enhancement by the entrainment of intermediate waters. Since these include the water masses formed by deep convection in the Labrador and southern Irminger Seas, our study offers an alternative interpretation of the dynamical role of decadal changes in Labrador Sea convection intensity in terms of a remote effect on the deep transports established in the outflow regimes.

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Seismic structure of the Cheb Basin from high resolution surveying – data quality assessment and first results

10.5194/egusphere-egu21-10124 ◽

2021 ◽

Author(s):

Natalia Banasiak ◽

Florian Bleibinhaus

Keyword(s):

High Resolution ◽

Earthquake Activity ◽

Seismic Structure ◽

North West ◽

The North ◽

Eger Rift ◽

First Results ◽

Ground Roll ◽

Variscan Granites ◽

Cheb Basin

In this study we present data and preliminary results from several shallow high-resolution seismic surveys in the Cheb Basin, CR, a small intracontinental basin in the North-West Bohemian Massif, located at the Western end of the Cenozoic Eger Rift. The area is well known for its intense earthquake activity, with the largest instrumentally recorded magnitude of ML=4.6. Macroseismic reports of local seismicity date back to the early 19th century, with magnitudes possibly above 5. Quaternary volcanoes, CO2-rich moffettes, and the swarm-like occurrence of the earthquakes suggest they are being triggered by crustal fluids. In contrast, most focal mechanisms show a dominant strike-slip component, indicative of tectonics. Investigating the role of fluids in triggering those earthquakes is one of the objectives of an ongoing ICDP program.We expect high-resolution images of the basin structure to provide additional constraints regarding the importance of tectonic faulting. To that end, we surveyed several up to 3-km-long reflection and refraction profiles in the basin center across the putative Po&#269;&#225;tky-Plesn&#225; Fault, and at its edge, across the basin-bounding Mari&#225;nsk&#233; L&#225;zn&#283; Fault. The up to 350-m-thick basin sediments are mostly of Miocene and Quaternary origin, overlying Paleozoic Variscan units and post-Variscan granites. The main reflectors are around 200-400 ms. The data were collected with a 500-m-long split-spread of single geophones at 2 m spacing, and the raw shots are dominated by ground roll. In this presentation, we will show an overview of the field campaigns and present first results.

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First Results on High Resolution Seismic Survey in the Arkona Basin, Baltic Sea

10.3997/2214-4609-pdb.299.35 ◽

1997 ◽

Author(s):

F. Theilen ◽

A. Ayres ◽

G. Lange ◽

M. Reidel ◽

C. Papenberg ◽

...

Keyword(s):

High Resolution ◽

Baltic Sea ◽

Seismic Survey ◽

First Results ◽

Arkona Basin

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