ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Bulk electronic structure of SrTiO3: Experiment and theory (2001)

van Benthem, K. ; Elsässer, C.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 90 (2001), S. 6156-6164

add to mindlist on the mindlist

Details

ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: Valence electron-energy loss spectroscopy (VEELS) in a dedicated scanning transmission electron microscope, vacuum ultraviolet spectroscopy and spectroscopic ellipsometry, and ab initio band structure calculations in the local density approximation have been used to determine the optical properties and the electronic structure of SrTiO3. Assignments of the interband transitions in the electronic structure of bulk SrTiO3 have been determined quantitatively by comparison of VEELS spectra with vacuum ultraviolet spectra and with the ab initio calculated densities of states. The experimentally determined indirect band gap energy is 3.25 eV, while the direct band gap energy is 3.75 eV. The conduction bands in SrTiO3 correspond to the bands composed of mainly Ti 3d t2g and eg states, followed at higher energies by the bands of Sr 4d t2g and eg states, and free electron like states dominating at energies above 15 eV. The upper valence band (UVB) contains 18 electrons in dominantly O 2p states, hybridized with Ti and Sr states, and has a bandwidth of 5 eV. The interband transitions from the UVB to the Ti 3d bands and to the Sr 4d bands give rise to the transitions spanning from the indirect band gap energy of 3.25 eV up to 15 eV. The lower valence band contains 12 electrons in Sr 4p and O 2s states which are separated by 2 eV, while having a bandwidth of 5 eV. The interband transitions from the Sr 4p to the Ti 3d and Sr 4d bands give rise to transition energies spanning from 15 to 24 eV. Interband transitions from the O 2s band to the conduction bands appear at 26 eV. A very narrow band at −33 eV below the top of the valence band is composed of Sr 4s and Ti 3p states and contains eight electrons. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1415766

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Ab-Initio Investigation of Metal-Ceramic Bonding: M(001)/MgAl2O4(001), M = Al, Ag (2000)

Köstlmeier, S. ; Elsässer, C.

Springer

Interface science 8 (2000), S. 41-54

add to mindlist on the mindlist

Details

ISSN: 1573-2746

Keywords: metal-ceramic interfaces ; interfacial bonding ; work of adhesion ; local density functional theory ; mixed-basis pseudopotential method

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Abstract The optimised adhesion geometry and the work of adhesion were determined for the interface systems Al(001)/MgAl2O4(001) and Ag(001)/MgAl2O4(001) by ab-initio density-functional calculations. Al is bound strongly on-top of oxygen at reduced lattice spacing, whereas weak adhesion and no unique optimum structure are obtained for Ag. An analysis of the electronic structure shows that in both systems the metal-ceramic interaction is spatially confined to a narrow range along the interface layers. The weak adhesion of Ag on spinel is mediated by a polarisation of the metal film, which may be classified as an image-charge interaction. In the case of Al a weak image-charge contribution is dominated by a strong electron-density redistribution perpendicular to the interface, which leads to the formation of directional Al—O bonds.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1008731219968

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Unknown

Simulating ice core 〈sup〉10〈/sup〉Be on the glacial–interglacial timescale (2015)

Elsässer, C. ; Wagenbach, D. ; Levin, I. ; [et al.]

COPERNICUS GESELLSCHAFT MBH

In: EPIC3Climate of the Past, COPERNICUS GESELLSCHAFT MBH, 11(2), pp. 115-133, ISSN: 1814-9332

add to mindlist on the mindlist

Details

Publication Date: 2016-11-14

Description: 10Be ice core measurements are an important tool for paleoclimate research, e.g., allowing for the reconstruction of past solar activity or changes in the geomagnetic dipole field. However, especially on multi-millennial timescales, the share of production and climate-induced variations of respective 10Be ice core records is still up for debate. Here we present the first quantitative climatological model of the 10Be ice concentration up to the glacial–interglacial timescale. The model approach is composed of (i) a coarse resolution global atmospheric transport model and (ii) a local 10Be air–firn transfer model. Extensive global-scale observational data of short-lived radionuclides as well as new polar 10Be snow-pit measurements are used for model calibration and validation. Being specifically configured for 10Be in polar ice, this tool thus allows for a straightforward investigation of production- and non-production-related modulation of this nuclide. We find that the polar 10Be ice concentration does not immediately record the globally mixed cosmogenic production signal. Using geomagnetic modulation and revised Greenland snow accumulation rate changes as model input, we simulate the observed Greenland Summit (GRIP and GISP2) 10Be ice core records over the last 75 kyr (on the GICC05modelext timescale). We show that our basic model is capable of reproducing the largest portion of the observed 10Be changes. However, model–measurement differences exhibit multi-millennial trends (differences up to 87% in case of normalized to the Holocene records) which call for closer investigation. Focusing on the (12–37) b2k (before the year AD 2000) period, mean model–measurement differences of 30% cannot be attributed to production changes. However, unconsidered climate-induced changes could likely explain the model–measurement mismatch. In fact, the 10Be ice concentration is very sensitive to snow accumulation changes. Here the reconstructed Greenland Summit (GRIP) snow accumulation rate record would require revision of +28% to solely account for the (12–37) b2k model–measurement differences.

Repository Name: EPIC Alfred Wegener Institut

Type: Article , isiRev

Format: application/pdf

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

PDF

Fulltext

4

Unknown

Continuous 25-years aerosol records at coastal Antarctica: 1. Inter-annual variability of ionic compounds and links to climate indices. (2011)

Weller, Rolf ; Wagenbach, D. ; Legrand, M. ; [et al.]

Wiley-Blackwell

In: EPIC3Tellus., Wiley-Blackwell, 63B(5), pp. 901-919

add to mindlist on the mindlist

Details

Publication Date: 2019-12-03

Description: The aerosol climatology at the coastal Antarctic Neumayer Station (NM) was investigated based on continuous, 25 years long observations of biogenic sulfur components (methanesulfonate and non sea salt sulfate), sea salt and nitrate. Whilst significant long-term trends could only be detected for nitrate (-3.6±2.5% per year between 1983 and 1993 and +4.0±3.2% per year from 1993-2007), non-harmonic periodicities between 2 and 5 years were typical for all species. Dedicated time series analyses revealed that relations to sea ice extent and various circulation indices are weak at best or not significant. In particular, no consistent link between sea ice extent and sea salt loadings was evident suggesting only a rather local relevance of the NM sea salt record. Nevertheless, a higher Southern Annular Mode index tended to entail a lower biogenic sulfur signal. In examining the spatial uniformity of the NM findings we contrasted them to respective 17 years records from the coastal Dumont d’Urville Station (DDU). We found similar long term trends for nitrate, indicating an Antarctic-wide but not identifiable atmospheric signal, though any significant impact of solar activity or pollution could be ruled out. No inter-site variability on the multi annual scale was evident for the other ionic compounds.

Repository Name: EPIC Alfred Wegener Institut

Type: Article , isiRev

Format: application/pdf

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

PDF

Fulltext

5

Unknown

Long term variability of cosmogenic and terrigenous radionuclides observed in the coastal Antarctic troposphere (2010)

Elsässer, C. ; Wagenbach, D. ; Levin, I. ; [et al.]

In: EPIC3EGU General Assembly 2010, Vienna, AustriaMay 2010., 02

add to mindlist on the mindlist

Details

Publication Date: 2019-12-03

Repository Name: EPIC Alfred Wegener Institut

Type: Conference , notRev

Format: application/pdf

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

PDF

Fulltext

6

Unknown

Continuous 25-years aerosol records at coastal Antarctica: Part 2. Variability and climate implications of 7Be, 10 Be and 210Pb (2011)

Elsässer, C. ; Wagenbach, D. ; Weller, Rolf ; [et al.]

Wiley-Blackwell

In: EPIC3Tellus., Wiley-Blackwell, 63B(5), pp. 920-934

add to mindlist on the mindlist

Details

Publication Date: 2019-12-03

Description: We investigated the variability of 210Pb, 7Be and 10Be in coastal Antarctica aerosol samples based on continuous, monthly and annually resolved time series which we obtained from Neumayer Station over the period 1983 to 2008. Clear seasonal cycles peaking in the local summer half year stands out in being common to all three radionuclide records. However, MC-SSA time series analyses suggest that significant multi-annual changes are confined to a 4-5 years periodicity resembling that of the SAM circulation index in case of 210Pb and to the expected solar decadal cycle in case of the cosmogenic Be-isotopes. Both, changes in the meridional transport and surface inversion strength appear to drive the seasonal 210Pb cycle which generally peaks in November. In contrast, stratospheric air mass intrusion are proved to be the main reason for the Be-isotopes seasonality as revealed by enhanced 10Be/ 7Be ratios occurring broadly concurrently with the individual Be-isotopes and the 7Be/210Pb ratios during late summer/early autumn. Although both, the (annual) 10Be and the monthly 7Be records reflects the decadal solar modulated production signal the detailed pattern of their decadal changes essentially deviate for unknown reasons, though a substantial excess 7Be production by solar energetic particles could be ruled out.

Repository Name: EPIC Alfred Wegener Institut

Type: Article , isiRev

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

Fulltext

7

Unknown

Observations of atmospheric radionuclide cycles: The benefit for global paleoclimate studies (2011)

Elsässer, C. ; Wagenbach, D. ; Levin, I. ; [et al.]

In: EPIC3CTBTO Preparatory Commission, Vienna International Center, Austria.

add to mindlist on the mindlist

Details

Publication Date: 2019-07-17

Repository Name: EPIC Alfred Wegener Institut

Type: Conference , notRev

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

Fulltext

8

Unknown

Year-round record of bulk and size-segregated aerosol composition in central Antarctica (Concordia site) Part 2: Biogenic sulfur (sulfate and methanesulfonate) aerosol (2017)

Legrand, Michel ; Preunkert, Susanne ; Weller, Rolf ; [et al.]

COPERNICUS GESELLSCHAFT MBH

In: EPIC3Atmospheric Chemistry and Physics, COPERNICUS GESELLSCHAFT MBH, 17, pp. 14055-14073, ISSN: 1680-7316

add to mindlist on the mindlist

Details

Publication Date: 2019-12-03

Description: Multiple year-round (2006-2015) records of the bulk and size-segregated composition of aerosol were obtained at 15 the inland site of Concordia located in East Antarctica. The well-marked maximum of non-sea-salt sulfate (nssSO4) in January (84 ± 25 ng m-3 against 4.4 ± 2.3 ng m-3 in July) is consistent with observations made at the coast (280 ± 78 ng m-3 in January against 16 ± 9 ng m-3 in July at Dumont d’Urville, for instance). In contrast, the well-marked maximum of MSA at the coast in January (60 ± 23 ng m-3 at Dumont d’Urville) is not observed at Concordia (4.6 ± 2.4 ng m-3 in January). Instead, the MSA level at Concordia peaks in October (5.6 ± 1.9 ng m-3) and March (13.2 ± 6.1 ng m-3). As a result, a surprisingly low MSA to nssSO4 ratio (RMSA) is observed at Concordia in mid-summer (0.05 ± 0.02 in January against 0.25 ± 0.09 in March). We find that the low value of RMSA in mid-summer at Concordia is mainly driven by a drop of MSA levels that takes place in submicron aerosol (0.3 μm diameter). The drop of MSA coincides with periods of high photochemical activity as indicated by high ozone levels, strongly suggesting the occurrence of an efficient chemical destruction of MSA over the Antarctic plateau in mid-summer. The relationship between MSA and nssSO4 levels is examined separately for each season and indicates that concentration of non-biogenic sulfate over the Antarctic plateau does not exceed 1 ng m-3 in fall and winter and remains below 5 ng m-3 in spring. This weak non-biogenic sulfate level is discussed in the light of radionuclides (210Pb, 10Be, and 7Be) also measured on bulk aerosol samples collected at Concordia. The findings highlight the complexity in using MSA in deep ice cores extracted from inland Antarctica as a proxy of past DMS emissions from the southern ocean.

Repository Name: EPIC Alfred Wegener Institut

Type: Article , isiRev

Format: application/pdf

Permalink