Search

Physical chemistry, chemical physics 24(44), 27121 - 27127 (2022). doi:10.1039/D2CP02408J special issue: "Ions, electrons, coincidences and dynamics: Festschrift for John H.D. Eland", During the last decade, X-ray free-electron lasers (XFELs) have enabled the study of light–matter interaction under extreme conditions. Atoms which are subject to XFEL radiation are charged by a complex interplay of (several subsequent) photoionization events and electronic decay processes within a few femtoseconds. The interaction with molecules is even more intriguing, since intricate nuclear dynamics occur as the molecules start to dissociate during the charge-up process. Here, we demonstrate that by analyzing photoelectron angular emission distributions and kinetic energy release of charge states of ionic molecular fragments, we can obtain a detailed understanding of the charge-up and fragmentation dynamics. Our novel approach allows for gathering such information without the need of complex ab initio modeling. As an example, we provide a detailed view on the processes happening on a femtosecond time scale in oxygen molecules exposed to intense XFEL pulses., Published by RSC Publ., Cambridge

${\mathrm{D}}_{2}$ molecules, excited by linearly cross-polarized femtosecond extreme ultraviolet (XUV) and near-infrared (NIR) light pulses, reveal highly structured ${\mathrm{D}}^{+}$ ion fragment momenta and angular distributions that originate from two different four-step dissociative ionization pathways after four-photon absorption (one XUV $+$ three NIR). We show that, even for very low dissociation kinetic energy release $\ensuremath{\le}$ 240 meV, specific electronic excitation pathways can be identified and isolated in the final ion momentum distributions. With the aid of ab initio electronic structure and time-dependent Schr\"odinger equation calculations, angular momentum, energy, and parity conservation are used to identify the excited neutral molecular states and molecular orientations relative to the polarization vectors in these different photoexcitation and dissociation sequences of the neutral ${\mathrm{D}}_{2}$ molecule and its ${\mathrm{D}}_{2}^{+}$ cation. In one sequential photodissociation pathway, molecules aligned along either of the two light polarization vectors are excluded, while another pathway selects molecules aligned parallel to the light propagation direction. The evolution of the nuclear wave packet on the intermediate $B{\phantom{\rule{0.16em}{0ex}}}^{1}{\mathrm{\ensuremath{\Sigma}}}_{u}^{+}$ electronic state of the neutral ${\mathrm{D}}_{2}$ molecule is also probed in real time.

Aiming at the realisation of nuclear fusion reactors, the joining of W and steel parts is currently examined. Based on proposals to implement functionally graded steel/W materials (FGMs) in the joint to cope with thermal stresses, the present contribution introduces a novel fabrication method for steel/W FGMs. Electro Discharge Sintering (EDS) was used to consolidate Fe/W powders within milliseconds at atmosphere. Due to the short process time, the formation of detrimental intermetallic Fe-W precipitates is limited compared to established fabrication methods. The current work first presents results of the Fe/W powder processing, then a feasibility study regarding the fabrication of homogeneous and graded Fe/W composites with W volume fractions of 0, 25, 50 and 75 % via EDS is presented. Lastly, the composites are characterised microstructurally, thermo-physically, and mechanically in detail.

Author(s): Heck, S; Gatton, A; Larsen, KA; Iskandar, W; Champenois, EG; Strom, R; Landers, A; Reedy, D; Dailey, C; Williams, JB; Severt, T; Jochim, B; Ben-Itzhak, I; Moshammer, R; Dorner, R; Slaughter, DS; Weber, T | Abstract: We present an experimental investigation of symmetry breaking of H2 and D2 molecules after single photoionization due to the Coulomb field of the emitted slow electron interacting with the parent cation during dissociation. The experiments were carried out by measuring the three-dimensional momentum vectors of the photoelectron and recoiling ion in coincidence using a reaction microscope. For photon energies close to threshold, the low-energy photoelectron influences the dissociation process, which results in an asymmetric molecular frame photoelectron angular distribution. This can be explained by the retroaction of the Coulomb field of the photoelectron on its parent ion and has been recently experimentally demonstrated by M. Waitz et al. [Phys. Rev. Lett. 116, 043001 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.043001], confirming theoretical predictions by V. V. Serov and A. S. Kheifets [Phys. Rev. A 89, 031402(R) (2014)PLRAAN1050-294710.1103/PhysRevA.89.031402]. High-momentum resolution and a new series of photon energies just above the dissociation threshold enable the observation of a strong influence of the electron energy and nuclear kinetic energy on the electron localization process for energies below ∼100 meV, which so far has neither been observed nor discussed by theory. Exploring the limitations of the retroaction mechanism at our lowest photon energy, we are able to single out a sensitive testbed and present data of non-Born-Oppenheimer dynamics of the simplest molecular system for future benchmark computational treatments.

We present a combined experimental and theoretical investigation of the electron dynamics and body-frame angular dependence of valence photo-single ionization of CF4 and subsequent dissociation into CF3+ and F. Ionization from a valence t2 orbital shows overlapping shape resonances close to threshold that couple to the same total symmetry, leading to striking changes in the photoelectron angular distributions when viewed in the body-frame.

In this work we present a comprehensive and detailed study of Interatomic Coulombic Decay (ICD) occurring after irradiating argon dimers with XUV-synchrotron radiation. A manifold of different decay channels is observed and the corresponding initial and final states are assigned. Additionally, the effect of nuclear dynamics on the ICD electron spectrum is examined for one specific decay channel. The internuclear distance-dependent width Γ ( R ) of the decay is obtained from the measured kinetic energy release distribution of the ions employing a classical nuclear dynamics model.

Author(s): Iskandar, W; Gatton, AS; Gaire, B; Sturm, FP; Larsen, KA; Champenois, EG; Shivaram, N; Moradmand, A; Williams, JB; Berry, B; Severt, T; Ben-Itzhak, I; Metz, D; Sann, H; Weller, M; Schoeffler, M; Jahnke, T; Dorner, R; Slaughter, D; Weber, T | Abstract: We have conducted an experimental study on the photo double ionization (PDI) of carbon-dioxide dimers at photon energies of 37 and 55 eV and oxygen dimers at photon energies of 38, 41.5, and 46 eV, while focusing on the dissociation dynamics upon single-photon absorption. The investigation was performed by applying the cold-target recoil-ion momentum spectroscopy method in order to collect and record the three-dimensional momenta of the ionic fragments and emitted electrons from the dissociating dimer in coincidence. The kinetic-energy release upon fragmentation and the electron angular distributions in the laboratory and body-fixed frames, as well as the relative electron-electron emission angle, show unambiguous experimental evidence of intermolecular Coulombic decay (ICD) in carbon-dioxide dimers upon photoionization below and above the double-ionization threshold of CO2 monomers. The PDI of oxygen dimers is less conclusive and shows contributions from ICD and knock-off ionization mechanisms. As for atomic dimers, the present results reveal that ICD in CO2 dimers after valence PDI can also serve as a source for low-energy electrons, known to be very relevant in biological systems, cells, and tissues.

Functionally graded steel/tungsten layers may be used as interlayers in the first wall of future fusion reactors to balance thermally-induced stress peaks in the steel‑tungsten joint. In this work, a modified water-stabilized atmospheric plasma spraying set-up is used to deposit uniform and functionally graded steel/tungsten coatings at elevated substrate temperatures. Uniform coatings were used to characterise individual sublayers of graded coatings in detail. The thermal expansion, thermal conductivity, Young's modulus and yield strength of the layers are promising for the application in steel‑tungsten joints and can be explained by microstructural observations. Only at a substrate preheating temperature of 900 °C the formation of intermetallic precipitates during deposition was observed.

Gas-phase activation and liquid-phase activation were compared for a suite of CoMo/Al2O3 catalysts with phosphoric acid (PA) and/or citric acid (CA) as additives. Gas-phase activation was carried out in 1 or 20 bar H2/H2S(10%), whereas liquid-phase activation comprised sulfidation in a model diesel feed, spiked with dimethyldisulfide and 20 bar H2. Full sulfidation of calcined precursors was difficult to achieve (type I), as shown by XPS and EXAFS. CA addition slowed the sulfidation of cobalt and molybdenum in 1 bar H2/H2S compared to a catalyst with no additives, but it substantially increased sulfidation rates in 20 bar H2/H2S. This can be attributed to reduced support interactions and enhanced reducibility of molybdenum. Liquid-phase sulfidation was initiated by a release of H2S at ∼250 °C due to decomposition of the spiking agent dimethyldisulfide. The resulting active phase was composed of predominantly MoS2 single-layers, whereas stacked layers formed after gas-phase activation. Catalytic activity in thiophene and DBT HDS mainly depended on the number of promoted sites. Catalysts prepared with CA had the highest degree of promotion and were most active in thiophene and DBT HDS, whereas the catalyst with PA performed best in gas-oil HDS due to increased stability.

Synopsis We have conducted an experimental study on the photo double ionization (PDI) of carbon dioxide dimers and oxygen dimers, while focusing on the dissociation dynamics upon single photon absorption. The results in terms of the kinetic energy and angular distributions of the charged particles show unambiguous experimental evidence of intermolecular Coulombic decay (ICD) in carbon dioxide dimers. In the oxygen dimer, the results show that ICD is accompanied by knock-off ionization mechanisms.

Synopsis New experimental results are presented on the dissociation dynamics of small neutral molecules in time-resolved photoexcitation-photoionization experiments by ultrashort vacuum- and extreme-ultraviolet laser pulses and charged particle momentum imaging.

Author(s): Reedy, D; Williams, JB; Gaire, B; Gatton, A; Weller, M; Menssen, A; Bauer, T; Henrichs, K; Burzynski, P; Berry, B; Streeter, ZL; Sartor, J; Ben-Itzhak, I; Jahnke, T; Dorner, R; Weber, T; Landers, AL | Abstract: We demonstrate the use of cold target recoil ion momentum spectroscopy to perform state-selective measurements of the dissociative channels following single-photon double-ionization of H2O. The two dominant dissociation channels observed lead to two-body (OH++H++2e-) and three-body (2H++O+2e-) ionic fragmentation channels. In the two-body case we observe the presence of an autoionization process with a double-differential cross section that is similar to the single-photon double-ionization of helium well above threshold. In the three-body case, momentum and energy correlation maps in conjunction with new classical trajectory calculations in the companion theory paper by Z. L. Streeter et al. [Phys. Rev. A 98, 053429 (2018)10.1103/PhysRevA.98.053429] lead to the determination of the eight populated dication states and their associated fragmentation geometry. For the latter case, state-specific relative cross sections, median kinetic energy releases, and median angles between asymptotic proton momenta are presented. This benchmark-level experiment demonstrates that, in principle, state-selective fixed-frame triple-differential cross sections can be measured for some dication states of the water molecule.

We present a combined experimental and theoretical investigation of the electron dynamics and body-frame angular dependence of valence photo-single ionization of CF4 and subsequent dissociation into CF3+ and F. Ionization from a valence t2 orbital shows overlapping shape resonances close to threshold that couple to the same total symmetry, leading to striking changes in the photoelectron angular distributions when viewed in the body-frame.

This paper describes the main activities carried out in the frame of EU-DA prequalification for the supply of Normal Heat Flux (NHF) First Wall (FW) panels to ITER. A key part of these activities is the manufacturing development, the fabrication and the factory acceptance tests of a reduced scale FW prototype (Semi-Prototype (SP)) of the NHF design. The SP has a dimension of 221 mm × 665 mm, corresponding to about 1/6 of a full-scale panel, with six full-scale “fingers” and bearing a total of 84 beryllium tiles. It has been manufactured by the AREVA Company in France. The manufacturing process has made extensive use of Hot Isostatic Pressing, which was developed over more than a decade during the ITER Engineering Design Activity phase. The main manufacturing steps for the Semi-Prototype are recalled, with a summary of the lessons learned and the implications with regard to the design and manufacturing of the full-scale prototype and of the series fabrication of the EU-DA share of the ITER first wall (215 NHF panels). The fabricated SP is then tested under High Heat Flux (HHF) in the dedicated test facility of JUDITH-II in Forschungszentrum Julich, Germany. The objective of the HHF testing is the demonstration of achieving the requested performance under thermal fatigue. The test protocol and facility qualification are presented and the behaviour of the fingers under the 7500 cycles at 2 MW/m2 is described in detail.

An in situ characterization of heterogeneous catalysts under industrial operating conditions may involve high pressure and reactants in both the gas and the liquid phase. In this paper, we describe an in situ XAS flow reactor, which is suitable to operate under such conditions (pmax 20 bar, Tmax 350 °C) and report its use in studying hydrodesulfurization (HDS) catalyst activation. The effect of pressure (1 or 20 bar) and sulfiding agent on the sulfidation rate of a CoMo/Al2O3 catalyst prepared with phosphate and polyethyleneglycol is determined from in situ XANES at the Co and Mo K-edges. Cobalt is sulfided substantially faster in 20 bar compared to 1 bar H2/H2S (gas phase activation), whereas the effect of pressure on molybdenum sulfidation is smaller. Liquid phase activation in 20 bar H2 and a model diesel feed (n-hexadecane/tert-nonylpolysulfide (TNPS)) starts at 190 °C, initiated by the in situ formation of H2S from TNPS, and is rapidly completed. Thus, pressure and sulfiding agent have a substantial effect on the sulfidation rate of HDS catalysts. The in situ XAS approach introduced here enables studying catalysts under industrial operating conditions and is applicable to not only hydrodesulfurization catalysts, but to any other catalytic system that requires high pressure and reactants in a gas/liquid mixture.

We used ultrashort femtosecond vacuum ultraviolet (VUV) and infrared (IR) pulses in a pump-probe scheme to map the dynamics and nonequilibrium dissociation channels of excited neutral H2 molecules. A nuclear wave packet is created in the BΣu+1 state of the neutral H2 molecule by absorption of the ninth harmonic of the driving infrared laser field. Due to the large stretching amplitude of the molecule excited in the BΣu+1 electronic state, the effective H2+ ionization potential changes significantly as the nuclear wave packet vibrates in the bound, highly electronically and vibrationally excited B potential-energy curve. We probed such dynamics by ionizing the excited neutral molecule using time-delayed VUV-or-IR radiation. We identified the nonequilibrium dissociation channels by utilizing three-dimensional momentum imaging of the ion fragments. We found that different dissociation channels can be controlled, to some extent, by changing the IR laser intensity and by choosing the wavelength of the probe laser light. Furthermore, we concluded that even in a benchmark molecular system such as H2∗, the interpretation of the nonequilibrium multiphoton and multicolor ionization processes is still a challenging task, requiring intricate theoretical analysis, We acknowledge many fruitful discussions and advice from R. Dorner, M. S. Schoffler, L. Ph. Schmidt, and Wei Cao. We are indebted to O. Jagutzki and A. Czasch from Roentdek GmbH and T. Jahnke from Cronologic GmbH for outstanding support for their momentum imaging detectors readout and software. F.S. acknowledges financial support by Studienstiftung des deutschen Volkes. A.P. and F.M.acknowledge the European COST Action XLIC CM1204, the European Research Council Advanced Grant XCHEM No. 290853, and the MINECO Project No. FIS2013-42002-R. X.M.T. was supported by a Grand-in-Aid for Scientific Research from the Japan Society for the Promotion of Science and Interdisciplinary Computational Science Program in Center for Computational Sciences, University of Tsukuba. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, and by the Division of Chemical Sciences, Geosciences, and Biosciences of the U.S. Department of Energy at LBNL under Contract No. DE-AC02-05CH11231

Organic additives and phosphoric acid are often reported to enhance the catalytic activity of MoS2-based hydrodesulfurization (HDS) catalysts, although the origin of their effect is not well understood. We did a systematic study on the effect of chelating and non-chelating additives on catalyst activation (1 bar and 20 bar H2/H2S) and on structure and activity of sulfided Mo/Al2O3 and CoMo/Al2O3 catalysts. Phosphoric acid (PA) lowers the activity of Mo/Al2O3 catalysts but does increase the activity of CoMo/Al2O3 catalysts due to reduced Co9S8 formation and improved promotion by cobalt. Organic additives enhance the activity of promoted catalysts more than those of unpromoted ones, indicating that their main role is to improve Cosingle bondMo interaction. Catalysts prepared with α-hydroxycarboxylic acids (citric acid and related compounds) are more active than those prepared with aminopolycarboxylic acids (NTA, EDTA). The α-hydroxycarboxylic acids improve sulfidation of molybdenum and cobalt by forming weak complexes that can be readily sulfided, yielding catalysts with optimal Cosingle bondMo interaction. It is proposed that promoted sites in alumina-supported catalysts are in centrosymmetric sulfur coordination with a Cosingle bondS CN > 4, which excludes tetrahedral Cosingle bondMosingle bondS sites.

We have developed a delay-line read-out technique for microchannel plate detectors with an increased acceptance for multiple hit events compared to standard two-layer delay-line anodes. This technique allows unambiguous determination of arrival time and position of at least four simultaneously detected particles, and/or to detect an even larger number of particles in a shower, as long as any two particles do not arrive both at the same time and at the same position within certain limits. We demonstrate and discuss the abilities and limitations of this technique and the relevance for certain experimental tasks.

© 2016 Author(s). We present a new experimental setup for measuring ultrafast nuclear and electron dynamics of molecules after photo-excitation and ionization. We combine a high flux femtosecond vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) source with an internally cold molecular beam and a 3D momentum imaging particle spectrometer to measure electrons and ions in coincidence. We describe a variety of tools developed to perform pump-probe studies in the VUV-XUV spectrum and to modify and characterize the photon beam. First benchmark experiments are presented to demonstrate the capabilities of the system.

Background In this multi-centre, randomised, placebo-controlled pilot trial, we investigated the clinical and haemodynamic effects of the endothelin-receptor blocker Bosentan in patients with heart failure, preserved ejection fraction and pulmonary hypertension (PH-HFpEF). Materials and Methods Eligible patients received either 12 weeks of Bosentan therapy, or a placebo drug. Patients were thereafter followed for a further period of 12 weeks without the study medication. At three points during the study (study Commencement, Week 12 and Week 24), a six-minute walk test (6MWT), echocardiographic and laboratory assessments were performed, as well as a quality of life survey. Right heart catheterisation (RHC) was undertaken at commencement only. The study was aborted early, after an interim analysis favoured the placebo. Results Six-minute walk distance (6MWD) did not change in the Bosentan group (309.7 ± 96.3m (Commencement), 317.0 ± 126.1m (Week 12), 307.0 ± 84.4m (Week 24); p = 0.86), but almost reached statistical significance in the placebo group from 328.8 ± 79.6m, to 361.6 ± 98.2m and 384.0 ± 74.9m (Week 24); p = 0.075. In the placebo group, estimated systolic pulmonary artery pressure (measured via echocardiography) significantly decreased (from 62.3 ± 16.7 mmHg [Commencement], 45.3 ± 13.9 mmHg [Week 12], to 44.6 ± 14.5 mmHg [Week 24]; p = 0.014) as did right atrial pressure (13.1 ± 5.3 [Commencement], 10.0 ± 3.8 [Week 12], to 9.4 ± 3.2 [Week 24]; p = 0.046). Conclusion Despite this study's limited sample size and premature cessation, it nevertheless suggests that endothelin receptor blockade in patients with PH-HFpEF may have no beneficial effects and could even be detrimental in comparison to a placebo.

DEMO is the name for the first stage prototype fusion reactor considered to be the next step after ITER towards realizing fusion. For the realization of fusion energy especially, materials questions pose a significant challenge already today. Heat, particle and neutron loads are a significant problem to material lifetime when extrapolating to DEMO. For many of the issues faced, advanced materials solutions are under discussion or already under development. In particular, components such as the first wall and the divertor of the reactor can benefit from introducing new approaches such as composites or new alloys into the discussion. Cracking, oxidation as well as fuel management are driving issues when deciding for new materials. Here composites as well as strengthened CuCrZr components together with oxidation resilient tungsten alloys allow the step towards a fusion reactor. In addition, neutron induced effects such as transmutation, embrittlement and after-heat and activation are essential. Therefore, when designing a component an approach taking into account all aspects is required.

State-of-the-art multi-fragment imaging techniques like the COLTRIMS reaction microscope unveil the complete momentum pattern in low-energy atomic and molecular many-particle fragmentation processes much like the bubble chamber in high-energy particle physics. The excellent momentum resolution far below 1 m e a 0 E h/ħ (1 a.u.) and the high multi-fragment detection efficiency of the COLTRIMS technique reveal the dynamic correlation of bound many-particle systems as they are fragmented into the continuum. For the fragmentation process of carbon monoxide following carbon K-shell ionization using 306 eV photons (right and left circularly polarized) hν + CO → ephoto + O+ + C+ + eK-Auger, the vector correlations between all fragments were measured in coincidence for each event. According to the common view of this process, the photoelectron and Auger electron emission probe different aspects of the time-dependent fragmentation process, i.e. the ‘time evolution’ of fragmentation. Based on measured vectors and v...

Damit sich neue Werkstoffvarianten durchsetzen, muss bei allen an der Herstellung und Verarbeitung beteiligten Akteuren neben der technischen auch die wirtschaftliche Vorteilhaftigkeit gegeben sein, die wiederum wesentlich von der Effizienz der neu zu gestaltenden bzw. zu verandernden Prozessketten beeinflusst wird. Eine werkstoffbezogene Wirtschaftlichkeitsbewertung muss daher auch die Prozessketten der Werkstoffherstellung und -verarbeitung umfassen. Die Bewertung von Prozessketten ist allerdings oft eine komplexe Aufgabenstellung, da diese sich aus vielfaltigen Prozessen, Teilprozessen und weiteren untergeordneten Prozessen zusammensetzen, auf die eine Vielzahl verschiedenartiger Grosen einwirkt. Gerade bei derartigen komplexen Problemstellungen besteht Bedarf an einem (kosten-)theoretisch fundierten Instrumentarium, das es ermoglicht, systematisch und strukturiert aussagekraftige Aufgabenlosungen zu erreichen. Im vorliegenden Beitrag soll daher ein entsprechendes Vorgehensmodell mit methodenbezogenen Vorschlagen zur Bewertung von Prozessketten zunachst konzipiert und anschliesend am Beispiel ausgewahlter Prozessketten der Verarbeitung von (im SFB 692 erforschten) aluminiumbasierten Leichtbauwerkstoffen veranschaulicht werden. To become widely accepted, new materials have to be technically and economically advantageous from the perspective of all companies which are involved in materials production and processing. Since economic advantages, caused by materials, are influenced by the efficiency of new or modified process chains of materials production and processing to a considerable degree, the appraisal of materials has to include these process chains. However, the evaluation of process chains is a complex task because they consist of varied processes, sub-processes and further subordinated processes which are influenced by a huge number of heterogeneous variables. Especially in case of such complex problems, instruments which are substantiated by (cost) theory can provide approaches to achieve conclusive solutions in a systematic and structured way. Therefore, in this paper a procedure model and methodological proposals for evaluation of process chains are conceptualized and illustrated by the evaluation of selected chains of processing of aluminum-based light weight materials which are objects of research within SFB 692.

Der Lebenszykluserfolg von Werkstoffen wird nicht nur durch deren Kosten, sondern auch durch die in Abhangigkeit von ihnen erzielbaren Erlose masgeblich beeinflusst. Daher ist es notig, sowohl diese Erlose als auch die Kundenanforderungen, deren Erfullung wiederum fur die Erloserzielung masgeblich ist, systematisch und strukturiert in werkstoffbezogenen Entscheidungsprozessen zu berucksichtigen. Diesem bisher weitgehend vernachlassigten Aufgabengebiet widmet sich der Aufsatz, in dem zunachst die Schrittfolge eines werkstoffbezogenen Anforderungsmanagements sowie die potentiellen Beitrage der Conjoint-Analyse und des Quality Function Deployment zu diesem dargestellt und diskutiert werden. Danach werden mit dem Conjoint+ Cost und dem Target Costing zwei Ansatze vorgestellt, die zur Prognose und gezielten Beeinflussung werkstoffabhangiger Erlose nutzbar sind. The life cycle profit of materials is considerably influenced not only by their costs, but also by revenues which can be generated with them. Therefore, it is necessary to integrate systematically these revenues as well as customer requirements, whose fulfillment affects revenues to a high degree, into material-referred decision-making processes. This paper applies to this hitherto largely neglected field of activity. Initially, steps of a material-specific requirements management as well as potential contributions to this by Conjoint Analysis and Quality Function Deployment are presented and discussed. Subsequently, Conjoint+Cost and Target Costing are introduced as two approaches which can be used to forecast and to specifically influence material-referred revenues.

Eine langfristig erfolgreiche Entwicklung, Herstellung und Verwendung von (neuen) Werkstoffen setzt voraus, dass die daran beteiligten, auf wirtschaftlichen Erfolg angewiesenen Unternehmen mit diesen Werkstoffen einen positiven monetaren Lebenszykluserfolg erzielen. Die Ermittlung eines solchen Lebenszykluserfolgs ist allerdings eine komplexe Aufgabenstellung, wird dieser doch durch eine Vielzahl verschiedenartiger unternehmensexterner und -interner Grosen beeinflusst. Gerade bei derartigen komplexen Problemstellungen bietet es sich an, Vorgehensmodelle fur eine systematische und strukturierte Problemanalyse und -zerlegung sowie die darauf basierende Bildung und Auswertung von monetaren Lebenszyklusmodellen zu nutzen. Im vorliegenden Beitrag soll daher ein Vorgehensmodell zur Ermittlung und Analyse des Lebenszykluserfolgs von Werkstoffen zunachst konzipiert und anschliesend anhand eines Fallbeispiels veranschaulicht werden. Long-term successful development, production and use of (new) materials presuppose that involved companies achieve a positive monetary life cycle benefit with these materials. However, the appraisal of this life cycle profit is a demanding task, since the profit is influenced by a huge number of different internal and external variables. Especially in case of such complex problems procedure models can support the systematic and structured analysis and decomposition of the problems as well as the creation and evaluation of monetary life cycle models basing on that. Therefore, this paper offers a suitable modeling approach for the life cycle profit of materials, which is illustrated by a case study.

Analysis of the electrons ionized from water dimers suggests that the energy absorbed by one molecule is rapidly transmitted to the second molecule from which the electron is ejected. This process, referred to as intermolecular Coulombic decay, is a qualitatively different source of low-energy electrons to conventional direct ionization processes. At the transition from the gas to the liquid phase of water, a wealth of new phenomena emerge, which are absent for isolated H2O molecules. Many of those are important for the existence of life, for astrophysics and atmospheric science. In particular, the response to electronic excitation changes completely as more degrees of freedom become available. Here we report the direct observation of an ultrafast transfer of energy across the hydrogen bridge in (H2O)2 (a so-called water dimer). This intermolecular coulombic decay leads to an ejection of a low-energy electron from the molecular neighbour of the initially excited molecule. We observe that this decay is faster than the proton transfer that is usually a prominent pathway in the case of electronic excitation of small water clusters and leads to dissociation of the water dimer into two H2O+ ions. As electrons of low energy (∼0.7–20 eV) have recently been found to efficiently break-up DNA constituents1,2, the observed decay channel might contribute as a source of electrons that can cause radiation damage in biological matter.

Intermolecular Coulombic decay transfers excess energy to neighbouring molecules, which then lose a low-energy (and, hence, genotoxic) electron; here the process is experimentally confirmed to be site-selective and highly efficient, possibly enabling more targeted radiation therapy. The irradiation of matter with light tends to electronically excite atoms and molecules. What happens to the resulting excitation energy depends on the nature of the relaxation pathway and the energy of the electrons and ions produced. In one such pathway, known as intermolecular Coulombic decay (ICD), excess energy is transferred to neighbouring atoms or molecules that then lose an electron and become ionized. ICD electrons have relatively low energy, prompting suggestions that they might be harnessed as a form of Auger therapy — cancer treatment that uses large numbers of genotoxic low-energy electrons to damage cancer cells. In a pair of papers [in this issue of Nature] published online this week, Gokhberg et al. propose that ICD can be triggered upon relaxation of an initial resonant core excitation, and Trinter et al. confirm the existence of the proposed excitation experimentally. The efficiency of this relaxation cascade and the fact that it can be tuned to directly control the generation site and the energy of the electrons raise the prospect of the development of more targeted cancer radiotherapy, and possibly new spectroscopic techniques. In 1997, it was predicted1 that an electronically excited atom or molecule placed in a loosely bound chemical system (such as a hydrogen-bonded or van-der-Waals-bonded cluster) could efficiently decay by transferring its excess energy to a neighbouring species that would then emit a low-energy electron. This intermolecular Coulombic decay (ICD) process has since been shown to be a common phenomenon2,3,4,5,6,7,8,9,10,11,12, raising questions about its role in DNA damage induced by ionizing radiation, in which low-energy electrons are known to play an important part13,14. It was recently suggested15 that ICD can be triggered efficiently and site-selectively by resonantly core-exciting a target atom, which then transforms through Auger decay into an ionic species with sufficiently high excitation energy to permit ICD to occur. Here we show experimentally that resonant Auger decay can indeed trigger ICD in dimers of both molecular nitrogen and carbon monoxide. By using ion and electron momentum spectroscopy to measure simultaneously the charged species created in the resonant-Auger-driven ICD cascade, we find that ICD occurs in less time than the 20 femtoseconds it would take for individual molecules to undergo dissociation. Our experimental confirmation of this process and its efficiency may trigger renewed efforts to develop resonant X-ray excitation schemes16,17 for more localized and targeted cancer radiation therapy.

Das Target Costing – in der Betriebswirtschaftslehre ein Standardinstrument des Kostenmanagement – findet in der wirtschaftlich orientierten Literatur zu den Werkstoffwissenschaften bisher kaum Erwahnung. Dabei bestehen auch fur die Entwickler, Hersteller oder Verwender von Werkstoffen grose Potentiale im Hinblick auf die Sicherung bzw. Verbesserung der Wirtschaftlichkeit. Daran setzt der vorliegende Beitrag an. In diesem werden zunachst diese Potentiale eines werkstoffbezogenen Target Costing herausgearbeitet. Dann wird aufgezeigt, wie die allgemeine Methodik des Target Costing aus der Sicht von Werkstoffverwendern einerseits und Werkstoffentwicklern/-herstellern andererseits zu modifizieren ist, um den Besonderheiten von Werkstoffen gerecht zu werden. Target Costing for Materials – Potentialities and Methodology Target Costing is a standard instrument of cost management in business administration, but hardly mentioned in the economic oriented literature on material sciences. Nevertheless there are high potentialities for developers, producers, or users of materials regarding the improvement of efficiency. Therefore, this article will present these potentialities of a material oriented Target Costing. Besides, the general methodology of Target Costing will be modified to meet the specifics of materials from the perspectives of users of materials on the one hand and developers respectively producers of materials on the other.

We report on fully differential cross sections for double ionization of H2 by a single circularly polarized photon of 160 eV energy. For an unequal sharing of the energy between the two electrons and a particular geometry where the influence of electron/electron interaction is constant, we find a four-lobe structure in the molecular frame angular distribution of the faster electron. This structure is interpreted to be due to a coherent emission of the electron from the two atomic centers of the molecule. This Young-type interference pattern is lost for other geometries, where electron-electron interaction plays a major role. Furthermore, we show that the interference structure depends strongly on the internuclear distance.

Interatomic Coulombic decay (ICD) in Ar2, ArKr and Kr2 following Ar 2p or Kr 3d Auger decay has been investigated by means of momentum-resolved electron-ion-ion coincidence spectroscopy. This sequen- tial decay leads to Coulombic dissociation into dication and monocation. Simultaneously determining the kinetic energy of the ICD electron and the kinetic energy release between the two atomic ions, we have been able to unambiguously identify the ICD channels. We find that, in general, spin-conserved ICD, in which the singlet (triplet) dicationic state produced via the atomic Auger decay preferentially decays to the singlet (triplet) state, transferring the energy to the other atom, is faster than spin-flip ICD, in which the Auger final singlet (triplet) dicationic state decays to the triplet (singlet) state. However, spin-flip ICD may take place when spin-conserved ICD becomes energetically forbidden. Dipole-forbidden ICDs from Kr2+(4s− 21 S)-B (B = Ar or Kr) to Kr2+(4p− 21 D, 3P)-B + are also observed.

Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question with an experiment that uses Auger electron angular emission patterns from molecular nitrogen after inner-shell ionization as an ultrafast probe of hole localization. The experiment, along with the accompanying theory, shows that observation of symmetry breaking (localization) or preservation (delocalization) depends on how the quantum entangled Bell state created by Auger decay is detected by the measurement.

A patient with high-grade osteoporosis had elevated levels of ACTH, cortisol and carcinoembryonic antigen (CEA). Computed tomography demonstrated enlarged adrenal glands. Despite intensive search no ACTH-producing tumour was found. A central Cushing's syndrome was thus possible, and a radiologically normal sella turcica made a microadenoma of the hypophysis a possibility. However, a one-time hypertensive crisis with elevated catecholamines raised the suspicion of an additional phaeochromocytoma and thus provided the first pointer to a multiple endocrine neoplasia. Bilateral phaeochromocytomas, discovered at adrenalectomy, as well as raised serum-calcitonin levels, strongly suggested coexistence of a C-cell carcinoma, which previously had not been demonstrated either by thyroid scanning or fine-needle biopsy. A total thyroidectomy revealed a multifocal and metastasizing C-cell carcinoma. On extraction it contained a high concentration of calcitonin, typical for a C-cell carcinoma. An unusual finding was of ACTH in extracts of both the C-cell carcinoma and the phaeochromocytoma. It was immunologically identical with the synthetic ACTH used as a standard.

In two female patients with hypothalamic-hypophyseal Cushing's syndrome who had not taken oral contraceptives, upper abdominal sonography showed three liver tumours as chance findings. In one case the left lobe was involved alone and in one case both lobes. None of the three tumours could be demonstrated by means of computer assisted tomography. Autopsy in one case and liver arteriography and scan in other other led to the diagnosis of focal nodular hyperplasia of the liver. These cases demonstrate the importance of sonography in the recognition of liver tumours. A connection between the overpopulation of adrenocorticosteroids and the formation or enlargement of focal nodular hyperplasia of the liver cannot be excluded.

H 2 , the smallest and most abundant molecule in the universe, has a perfectly symmetric ground state. What does it take to break this symmetry? We found that the inversion symmetry can be broken by absorption of a linearly polarized photon, which itself has inversion symmetry. In particular, the emission of a photoelectron with subsequent dissociation of the remaining H + 2 fragment shows no symmetry with respect to the ionic H + and neutral H atomic fragments. This lack of symmetry results from the entanglement between symmetric and antisymmetric H + 2 states that is caused by autoionization. The mechanisms behind this symmetry breaking are general for all molecules.

The fragmentation pathways and dynamics of ethylene molecules after core ionization are explored using coincident measurements of the Auger electron and fragment ions by employing the cold target recoil-ion momentum spectroscopy method. The influence of several factors on the dynamics and kinematics of the dissociation is studied. These include propensity rules, ionization mechanisms, symmetry of the orbitals from which the Auger electrons originate, multiple scattering, conical intersections, interference, and possible core-hole localization for the double ionization of this polyatomic molecule. Energy correlation maps allow probing the multidimensional potential energy surfaces and, in combination with our multiconfiguration self-consistent field calculations, identifying the populated electronic states of the dissociating dication. The measured angular distributions of the Auger electrons in the molecular frame further support and augment these assignments. The deprotonation and molecular hydrogen ion elimination channels show a nearly isotropic Auger electron angular distribution with a small elongation along the direction perpendicular to the molecular axis. For the symmetric breakup the angular distributions show a clear influence of multiple scattering on the outgoing electrons. The lowest kinetic energy release feature of the symmetric breakup channel displays a fingerprint of entangled Auger and photoelectron motion in the angular emission pattern identifying this transition as an excellent candidate to probe core-hole localization at a conical intersection of a polyatomic molecule.

Many-particle dynamics in atomic and molecular physics has been investigated by using the COLTRIMS reaction microscope. The COLTRIMS technique visualizes photon and ion induced many-particle fragmentation processes in the eV and milli-eV regime. It reveals the complete momentum pattern in atomic and molecular many-particle reactions comparable to the bubble chamber in nuclear physics.  2005 Elsevier B.V. All rights reserved.

Correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short as an attosecond) of the correlated dynamics between electrons and nuclei have been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics.

We present a joint experimental and theoretical study for the fully differential cross section of the photo double ionization (PDI) of helium with linearly polarized light at the excess energies Eexc = 100 eV and 450 eV above the threshold. The fully differential cross section is obtained by measuring the three-dimensional momentum vectors of one electron and the He 2+ ion in coincidence using the COLTRIMS method. We give an overview of the momentum distribution of the three-body continuum 100 eV above the threshold. We show angular distributions for both electrons for various energy sharings at Eexc = 100 eV and 450 eV. The experimental results are well reproduced by a set of convergent close-coupling (CCC) calculations.

We present a joint experimental and theoretical study of the gerade and ungerade amplitudes of the photo double ionization of helium at excess energies of 100 eV and 450 eV above the threshold. We describe a method of extracting the amplitudes from a COLTRIMS data set. The experimental results are well reproduced by convergent close-coupling (CCC) calculations. The fully differential cross section data underlying this study can be found in our companion papers immediately preceding this one.

The timing of molecular rearrangements can be followed in the time domain on a femtosecond scale by using momentum imaging techniques. Three examples are discussed in this paper: first, the diffraction of electrons ejected from the K-shell of one of the atomic constituents of the molecule takes a 'picture' of the molecule, and the correlation between the momentum vector of the photoelectron and the subsequent fragmentation pattern is used to estimate the time delay which accompanies the latter process. Second, the kinetic energy release of proton pairs from the double ionization of hydrogen by fast laser pulses is timed using the optical cycle as a clock. The mechanisms of rescattering, sequential and enhanced ionization are clearly identified in the momentum spectra. Third, the operation of rescattering double ionization in the case of nitrogen and oxygen molecules is discussed.

The nuclear motion and geometry in core-excited CO2 are probed using a multiple-ion-coincidence imaging technique. We demonstrate that CO2 has a linear stable geometry in the C/O 1s −1 core-ionized state and a bent geometry in the C/O 1s −1 * core-excited state. The molecules in the C/O 1s −1 *A 1 and B1 Renner–Teller states are probed to be bent in the A1 state and linear in the B1 state. The O O correlation angle distributions are well reproduced using a Coulomb explosion model which takes account of the zero point bending motion in the ground state, the classical bending motion along the potential energy curve of the core-excited state within the core-hole lifetime and the initial inhomogeneous charge distribution in the multiply charged molecular ion just before the dissociation. When the photon energy is tuned to be higher (lower) energy than the 1s −1 * resonance center, the events for the 1s −1 *A 1 states that result in the low O O correlation angle distribution are suppressed (enhanced).

This report will introduce the reader to the method of measuring electron and ion momentum distributions from fixed-in-space molecules using modified versions of the COLTRIMS technique. Following the introduction and a description of the working principles of this technique, a detailed discussion of the design of the electron and the ion detection part of the spectrometer will be presented. The actual measurement represents only a minor fraction of a COLTRIMS-like experiment. We therefore give an in-depth view at the basics of the offline-analysis for the field of detecting multiple particles from a Coulomb exploding molecule. Achievable resolutions, the possibilities of background suppression via multiparticle software coincidence methods, and the improvement of electron momentum resolution by center-of-mass-correction will be discussed, followed by an example of a setup for low energy electrons (

Fully differential cross-sections in momentum space for multiple ionization processes of atoms and molecules have been investigated by a multi-coincidence imaging technique, called COLTRIMS (cold target recoil ion momentum spectroscopy) (J. Phys. B 30 (1997) 2917; Nucl. Instrum. Methods B 108 (1996) 425; In: Ullrich, J., Shevelko, V.P. (Eds.), Many Particle Quantum Dynamics in Atomic Fragmentation, Series Atomic, Optical, and Plasma Physics, Vol. 35. Springer, Berlin, 2003; Phys. Rep. 330 (2000) 95). This technique is as powerful as the bubble chamber system in high-energy physics. It has opened a new observation window into the hidden world of many-particle dynamics: correlated many-particle dynamics in Coulombic systems can now be experimentally approached with unprecedented completeness and precision. The principle of the method, namely measuring the momentum of the emitted charged particles from an atomic or molecular fragmentation process, is as simple as determining the trajectory of a thrown stone. From knowing the position from where the stone was slung and where it hits the target, as well as measuring its time-of-flight, the trajectory of the stone and thus its initial velocity vector can be determined precisely. Furthermore, in order to achieve good precision we have to know whether the person, who throws the stone, was at rest in the frame of observation or with which relative velocity this person was moving. Thus, to obtain optimal momentum resolution for the exploding fragments one has to bring the fragmenting object to a complete rest in the frame of measurement before the reaction occurs, i.e. if the object is a gas atom or molecule one has to cool it down to sub-milli Kelvin temperatures.

Viscosity measurements of GaInSn eutectic alloys were performed in a homebuilt device for low (9%) and high (95%) relative humidity for shorter (450 min) and longer (1800 min) time periods. At constant exposure time a characteristic increase of viscosity is observed with increasing humidity. For high humidity, high viscosity is obtained after a short time. Assuming that the measured viscosity change is strongly related to the absorption of oxygen, XPS was applied to the chemical and quantitative analysis of differently prepared samples. In all cases, Ga is predominantly oxidized at the surface whereas Ga atoms in the metallic state are located deeper inside. Besides Ga 2 O 3 (the most stable oxide phase), the less stable Ga 2 O is detected. Indium and tin are almost stable in their metallic state. With increasing humidity the thickness of the oxide film increases in our case from about 19 A to 25 A, assuming a layer-by-layer model. The presented results confirm our assumption of the increase in viscosity of the GaInSn system as a consequence of the preferential oxidation of gallium in the near-surface region.