A Connection between Twistors and Superstring Sigma Models on Coset Superspaces (2009)
We consider superstring sigma models that are based on coset superspaces G/H in which H arises as the fixed point set of an order-4 automorphism of G. We show by means of twistor theory that the...
Marginal Deformations and 3-Algebra Structures (2009)
Akerblom, Nikolas, Saemann, Christian, Wolf, Martin
We study marginal deformations of superconformal Chern-Simons matter theories that are based on 3-algebras. For this, we introduce the notion of an associated 3-product, which captures very general...
Bovensiepen, Uwe, Declair, Stefan, Lisowski, Martin, Loukakos, Panagiotis A., Hotzel, Arthur, Richter, Marten, ...
We propose an approach to address ultrafast charge-carrier dynamics of metals by analyzing the momentum change in photoelectrons interacting with a transient optical grating at a metal surface....
A Dynamic Landscape from Femtoseconds to Minutes for Excess Electrons at Ice-Metal Interfaces (2009)
Bovensiepen, Uwe, Gahl, Cornelius, Stähler, Julia, Bockstedte, Michel, Meyer, Michael, Baletto, Francesca, ...
Stabilization of excess electrons is studied at crystalline ice-metal interfaces by femtosecond time-resolved two-photon photoelectron spectroscopy and ab initio calculations. Following optical...
Molecular switches represent a fascinating class of functional molecules, whose properties can be reversibly changed between different molecular states by excitation with light or other external...
Reactivity of water–electron complexes on crystalline ice surfaces (2009)
Bertin, Mathieu, Meyer, Michael, Stähler, Julia, Gahl, Cornelius, Wolf, Martin, Bovensiepen, Uwe
The interactions between long-living electrons trapped in defects of crystalline D2O and electronegative molecules have been investigated using two-photon photoemission spectroscopy. When covered by...
Ultrafast far-infrared optics of carbon nanotubes (2009)
Frischkorn, Christian, Kampfrath, Tobias, Perfetti, Luca, Von Volkmann, Konrad, Wolf, Martin
The optical properties of single-wall carbon nanotube sheets in the far-infrared (FIR) spectral range from few THz to several tens of THz have been investigated with terahertz spectroscopy both with...
Wagner, Steffen, Leyssner, Felix, Kördel, Christian, Zarwell, Sebastian, Schmidt, Roland, Weinelt, Martin, ...
Sum-frequency generation (SFG) vibrational spectroscopy is employed to investigate the reversible, photoinduced trans/cis isomerization of an azobenzene-functionalized self-assembled monolayer (SAM)...
Ultrafast dynamics of coherent optical phonons in α-quartz (2009)
Von Volkmann, Konrad, Kampfrath, Tobias, Krenz, Marcel, Wolf, Martin, Frischkorn, Christian
Piantek, Marten, Schulze, Gunnar, Koch, Matthias, Franke, Katharina J., Leyssner, Felix, Krüger, Alex, ...
The ring-opening/closing reaction between spiropyran (SP) and merocyanine (MC) is a prototypical thermally and optically induced reversible reaction. However, MC molecules in solution are...
Dual Superconformal Symmetry from AdS5 x S5 Superstring Integrability (2008)
Beisert, Niklas, Ricci, Riccardo, Tseytlin, Arkady, Wolf, Martin
We discuss 2d duality transformations in the classical AdS5 x S5 superstring and their effect on the integrable structure. T-duality along four directions in Poincare parametrization of AdS5 maps the...
Dual superconformal symmetry from AdS(5) x S-5 superstring integrability (2008)
Beisert, Niklas, Ricci, Riccardo, Tseytlin, Arkady A., Wolf, Martin
We discuss 2d duality transformations in the classical AdS5 x S5 superstring and their effect on the integrable structure. T-duality along four directions in Poincare parametrization of AdS5 maps the...
Transient electronic structure and melting of a charge density wave in TbTe3 (2008)
Schmitt, Felix, Kirchmann, Patrick S., Bovensiepen, Uwe, Moore, Rob G., Rettig, Laurenz, Krenz, Marcel, ...
Obtaining insight into microscopic cooperative effects is a fascinating topic in condensed matter research because, through self-coordination and collectivity, they can lead to instabilities with...
Perfetti, Luca, Loukakos, Panagiotis A., Lisowski, Martin, Bovensiepen, Uwe, Wolf, Martin, Berger, Helmuth, ...
Photoexcitation of the Mott insulator 1T-TaS2 by an intense laser pulse leads to an ultrafast transition toward a gapless phase. Beside the collapse of the electronic gap, the sudden excitation of...
Meyer, Michael, Stähler, Julia, Kusmierek, Daniela O., Wolf, Martin, Bovensiepen, Uwe
We investigate the binding site of solvated electrons in amorphous D2O clusters and D2O wetting layers adsorbed on Cu(111) by means of two-photon photoelectron (2PPE) spectroscopy. On the basis of...
Kirchmann, Patrick S., Rettig, Laurenz, Nandi, Dhananjay, Lipowski, Uwe, Wolf, Martin, Bovensiepen, Uwe
We developed a time-of-fight photoelectron spectrometer that simultaneously analyzes low energy electrons photoemitted from solid surfaces in an energy- and angle-resolved manner. To achieve this, a...
A femtosecond X-ray/optical cross-correlator (2008)
Gahl, Cornelius, Azima, Armin, Beye, Martin, Deppe, Martin, Döbrich, Kristian, Hasslinger, Urs, ...
For a fundamental understanding of ultra fast dynamics in chemistry, biology and materials science it has been a longstanding dream to record a molecular movie, where both the atomic trajectories and...
Stähler, Julia, Meyer, Michael, Kusmierek, Daniela O., Bovensiepen, Uwe, Wolf, Martin
Electron transfer (ET) dynamics at molecule-metal interfaces plays a key role in various fields as surface photochemistry or the development of molecular electronic devices. The bare transfer process...
Óvári, László, Schwarz, Jutta, Peters, Maike V., Hecht, Stefan, Wolf, Martin, Tegeder, Petra
High resolution electron energy loss spectroscopy (HREELS) is employed to analyze reversible changes in the geometrical structure of the molecular switch di-methoxy- tetra-tert-butyl-azobenzene...
Wagner, Steffen, Öström, Henrik, Kaebe, Alexander, Krenz, Marcel, Wolf, Martin, Luntz, Alan C., ...
The femtosecond-laser induced associative desorption of CO from a C/O coadsorbate on Ru(001) has been investigated. The recombination of the atomic reactants is found to originate predominantly from...
Mechanism of the Far-Infrared Absorption of Carbon-Nanotube Films (2008)
Kampfrath, Tobias, Von Volkmann, Konrad, Aguirre, C. M., Desjardins, Patrick, Martel, Richard, Krenz, Marcel, ...
The far-infrared conductivity of single-wall carbon-nanotube ensembles is dominated by a broad absorption peak around 4THz whose origin is still debated. We observe an overall depletion of this peak...
Hagen, Sebastian, Kate, Peter, Peters, Maike V., Hecht, Stefan, Wolf, Martin, Tegeder, Petra
Two-photon photoemission (2PPE) spectroscopy is employed to quantify the photochemically and thermally induced trans ⇌ cis isomerization of the molecular switch tetra-tert-butyl-azobenzene (TBA)...
Hagen, Sebastian, Kate, Peter, Leyssner, Felix, Nandi, Dhananjay, Wolf, Martin, Tegeder, Petra
Two-photon photoemission (2PPE) spectroscopy is employed to elucidate the electronic structure and the excitation mechanism in the photoinduced isomerization of the molecular switch...
Terahertz coherent control of optically dark paraexcitons in Cu2O (2008)
Leinß, Silvan, Kampfrath, Tobias, Von Volkmann, Konrad, Wolf, Martin, Steiner, Johannes T., Kira, Mackillo, ...
Intense multiterahertz fields of order megavolts per centimeter are used to coherently promote optically dark and dense paraexcitons in Cu2O from the 1s into the 2p state. The nonlinear field...
On T-Duality and Integrability for Strings on AdS Backgrounds (2007)
Ricci, Riccardo, Tseytlin, Arkady A., Wolf, Martin
We discuss an interplay between T-duality and integrability for certain classical non-linear sigma models. In particular, we consider strings on the AdS_5 x S^5 background and perform T-duality along...
Twistor Actions for Self-Dual Supergravities (2007)
Mason, Lionel J., Wolf, Martin
We give holomorphic Chern-Simons-like action functionals on supertwistor space for self-dual supergravity theories in four dimensions, dealing with N=0,...,8 supersymmetries, the cases where...
Self-Dual Supergravity and Twistor Theory (2007)
By generalizing and extending some of the earlier results derived by Manin and Merkulov, a twistor description is given of four-dimensional N-extended (gauged) self-dual supergravity with and without...
On supertwistor geometry and integrability in super gauge theory (2006)
In this thesis, we report on different aspects of integrability in supersymmetric gauge theories. The main tool of investigation is twistor geometry. In trying to be self-contained, we first present...
Hidden Symmetries and Integrable Hierarchy of the N=4 Supersymmetric Yang-Mills Equations (2006)
Popov, Alexander D., Wolf, Martin
We describe an infinite-dimensional algebra of hidden symmetries of N=4 supersymmetric Yang-Mills (SYM) theory. Our derivation is based on a generalization of the supertwistor correspondence. Using...
Presentations from the Repository Bridge publicity events (2006)
Lewis, Stuart, Bell, Jonathan, Wolf, Martin, Tedd, Lucy A.
Presentations from the Repository Bridge publicity events run on the 26th July 2006 in Bangor and the 3rd August 2006 in Cardiff.
Twistors and Aspects of Integrability of self-dual SYM Theory (2005)
With the help of the Penrose-Ward transform, which relates certain holomorphic vector bundles over the supertwistor space to the equations of motion of self-dual SYM theory in four dimensions, we...
Popov, Alexander D., Saemann, Christian, Wolf, Martin
In the recent paper hep-th/0502076, it was argued that the open topological B-model whose target space is a complex (2|4)-dimensional mini-supertwistor space with D3- and D1-branes added corresponds...
On Hidden Symmetries of a Super Gauge Theory and Twistor String Theory (2004)
We discuss infinite-dimensional hidden symmetry algebras (and hence an infinite number of conserved nonlocal charges) of the N-extented self-dual super Yang-Mills equations for general N\leq4 by...
Denzler,Daniel N., Frischkorn,Christian, Wolf,Martin, Ertl,Gerhard
Absorption of femtosecond near-infrared laser pulses in the surface near region of Ru(001) covered with atomic hydrogen induces recombinative desorption of its molecular species. The ultrafast time...
Topological B-Model on Weighted Projective Spaces and Self-Dual Models in Four Dimensions (2004)
Popov, Alexander D., Wolf, Martin
It was recently shown by Witten on the basis of several examples that the topological B-model whose target space is a Calabi-Yau (CY) supermanifold is equivalent to holomorphic Chern-Simons (hCS)...
Dephasing of highly vibrationally excited molecules at surfaces: CO/Ru(001) (2004)
Bonn,Mischa, Hess,Christian, Roeterdink,Wim G., Ueba,Hiromu, Wolf,Martin
Constraint and Super Yang-Mills Equations on the Deformed Superspace R^(4|16)_\hbar (2004)
Saemann, Christian, Wolf, Martin
It has been known for quite some time that the N=4 super Yang-Mills equations defined on four-dimensional Euclidean space are equivalent to certain constraint equations on the Euclidean superspace...
Dephasing of highly vibrationally excited molecules at surfaces: CO/Ru(001) (2004)
Bonn, Mischa, Hess, Christian, Roeterdink, Wim G., Ueba, Hiromu, Wolf, Martin
Denzler, Daniel N., Frischkorn, Christian, Wolf, Martin, Ertl, Gerhard
Absorption of femtosecond near-infrared laser pulses in the surface near region of Ru(001) covered with atomic hydrogen induces recombinative desorption of its molecular species. The ultrafast time...
Globalization and Global Economic Governance (2004)
This article focuses on the World Trade Organization (WTO) and the International Monetary Fund (IMF). It starts by noting that the case for creating such institutions is not self-evident, since the...
Electronic excitation and dynamic promotion of a surface reaction (2003)
Denzler,Daniel N., Frischkorn,Christian, Hess,Christian, Wolf,Martin, Ertl,Gerhard
The mechanism of recombinative desorption of hydrogen from a Ru(0001) surface induced by femtosecond-laser excitation has been investigated and compared to thermally initiated desorption. For the...
Interfacial structure of water on Ru(001) investigated by vibrational spectroscopy (2003)
Denzler,Daniel N., Hess,Christian, Dudek,Raymond, Wagner,Steffen, Frischkorn,Christian, Wolf,Martin, ...
In light of the controversial discussion of the interfacial structure of water on metal surfaces, adsorption of D2O on Ru(0 0 1) is investigated using sum-frequency generation vibrational...
Isotope effects in the thermal desorption of water from Ru(001) (2003)
Denzler,Daniel N., Wagner,Steffen, Wolf,Martin, Ertl,Gerhard
In the light of a recent theoretical study claiming partial dissociation of water on Ru(001) [Science 295 (2002) 99], the adsorption of the first layers of H2O and D2O on Ru(001) is investigated...
Seiberg-Witten Monopole Equations on Noncommutative R^4 (2003)
Popov, Alexander D., Sergeev, Armen G., Wolf, Martin
It is well known that, due to vanishing theorems, there are no nontrivial finite action solutions to the Abelian Seiberg-Witten (SW) monopole equations on Euclidean four-dimensional space R^4. We...
Ultrafast dynamics of recombinative desorption of hydrogen from a Ru(001) surface (2003)
Frischkorn,Christian, Wolf,Martin, Denzler,Daniel N., Hess,Christian, Ertl,Gerhard
Femtosecond-laser excitation induces recombinative desorption of molecular H-2 from atomic hydrogen on a ruthenium surface. The measured ultrafast timescale of this surface reaction reveals an...
Ultrafast dynamics of recombinative desorption of hydrogen from a Ru(001) surface (2003)
Frischkorn, Christian, Wolf, Martin, Denzler, Daniel N., Hess, Christian, Ertl, Gerhard
Femtosecond-laser excitation induces recombinative desorption of molecular H-2 from atomic hydrogen on a ruthenium surface. The measured ultrafast timescale of this surface reaction reveals an...
Isotope effects in the thermal desorption of water from Ru(001) (2003)
Denzler, Daniel N., Wagner, Steffen, Wolf, Martin, Ertl, Gerhard
In the light of a recent theoretical study claiming partial dissociation of water on Ru(001) [Science 295 (2002) 99], the adsorption of the first layers of H2O and D2O on Ru(001) is investigated...
Interfacial structure of water on Ru(001) investigated by vibrational spectroscopy (2003)
Denzler, Daniel N., Hess, Christian, Dudek, Raymond, Wagner, Steffen, Frischkorn, Christian, Wolf, Martin, ...
In light of the controversial discussion of the interfacial structure of water on metal surfaces, adsorption of D2O on Ru(0 0 1) is investigated using sum-frequency generation vibrational...
Electronic excitation and dynamic promotion of a surface reaction (2003)
Denzler, Daniel N., Frischkorn, Christian, Hess, Christian, Wolf, Martin, Ertl, Gerhard
The mechanism of recombinative desorption of hydrogen from a Ru(0001) surface induced by femtosecond-laser excitation has been investigated and compared to thermally initiated desorption. For the...
Noncommutative Instantons via Dressing and Splitting Approaches (2002)
Horvath, Zalan, Lechtenfeld, Olaf, Wolf, Martin
Almost all known instanton solutions in noncommutative Yang-Mills theory have been obtained in the modified ADHM scheme. In this paper we employ two alternative methods for the construction of the...
In this paper we study the noncommutative extension of a modified U(n) sigma model in 2+1 dimensions. Using the method of dressing transformations, an iterative approach for the construction of...
Femtosecond time-resolved vibrational SFG spectroscopy of CO/Ru(001) (2002)
Hess,Christian, Wolf,Martin, Roke,Sylvie, Bonn,Mischa
Vibrational sum-frequency generation (SFG) employing femtosecond infrared (IR) laser pulses is used to study the dynamics of the C–O stretch vibration on Ru(001). Time-resolved measurements of the...
Two-photon photoemission spectroscopy of pyridine adsorbed on Cu(111) (2002)
Zhong,Qun, Gahl,Cornelius, Wolf,Martin
Two-photon photoemission (2PPE) spectroscopy is employed to investigate the electronic structure of image potential states and unoccupied molecular resonances of pyridine adsorbed on Cu(111). The two...
Denzler,Daniel N., Hess,Christian, Funk,Stephan, Ertl,Gerhard, Bonn,Mischa, Frischkorn,Christian, ...
Fundamental insights into the ultrafast dynamics of energy transfer processes at surfaces are of central importance for a microscopic understanding of chemical reactions at solid surfaces, e.g. in...
Denzler, Daniel N., Hess, Christian, Funk, Stephan, Ertl, Gerhard, Bonn, Mischa, Frischkorn, Christian, ...
Fundamental insights into the ultrafast dynamics of energy transfer processes at surfaces are of central importance for a microscopic understanding of chemical reactions at solid surfaces, e.g. in...
Femtosecond time-resolved vibrational SFG spectroscopy of CO/Ru(001) (2002)
Hess, Christian, Wolf, Martin, Roke, Sylvie, Bonn, Mischa
Vibrational sum-frequency generation (SFG) employing femtosecond infrared (IR) laser pulses is used to study the dynamics of the C–O stretch vibration on Ru(001). Time-resolved measurements of the...
Two-photon photoemission spectroscopy of pyridine adsorbed on Cu(111) (2002)
Zhong, Qun, Gahl, Cornelius, Wolf, Martin
Two-photon photoemission (2PPE) spectroscopy is employed to investigate the electronic structure of image potential states and unoccupied molecular resonances of pyridine adsorbed on Cu(111). The two...
Zugl.: Aachen, Techn. Hochsch., Diss., 2002.
Moos, Gunnar, Gahl, Cornelius, Fasel, Roman, Wolf, Martin, Hertel, Tobias
Femtosecond time-resolved photoemission of photoexcited electrons in highly oriented pyrolytic graphite (HOPG) provides strong evidence for anisotropies of quasiparticle (QP) lifetimes. Indicative of...
The dynamics of vibrational excitations on surfaces: CO on Ru(001) (2001)
Bonn, Mischa, Hess, Christian, Wolf, Martin
We present an experimental and theoretical study of vibrational excitation of the C–O stretch vibration of carbon monoxide adsorbed on a ruthenium Ru(001) surface with ultrashort femtosecond...
Moos, Gunnar, Gahl, Cornelius, Fasel, Roman, Wolf, Martin, Hertel, Tobias
Femtosecond time-resolved photoemission of photoexcited electrons in highly oriented pyrolytic graphite (HOPG) provides strong evidence for anisotropies of quasiparticle (QP) lifetimes. Indicative of...
THz pump-probe measurements of electrons in non-polar liquids (2001)
Knoesel, Ernst, Shan, Jie, Bonn, Mischa, Wolf, Martin, Heinz, Tony F.
Terahertz time-domain spectroscopy is applied to examine the nature and dynamics of photo-generated carriers in non-polar liquids. The experimental results yield the complex conductivity of the...
Zugl.: Ilmenau, Techn. Universiẗat, Diss., 2000.
Artificiality of multifractal phase transitions (1999)
Wolf, Martin, Schmiegel, Jürgen, Greiner, Martin
A multifractal phase transition is associated to a nonanalyticity in the generalised dimensions. We show that its occurrence is an artifact of the asymptotic scaling behaviour of integral moments and...
Thesis (doctoral)--Universität GH Duisburg, 1996.
Jena, Univ., Diss., 1995.
The US and Europe in a Changing World. EIPAScope 1994(2):pp. 18-22 (1994)
[From the Introduction]. It has become increasingly obvious that 1989, the year communism collapsed, marked a watershed in world history. But it was not a watershed between an age of conflict, on the...
Unordnungseffekte in Modellen konjugierter Polymere [microform]. (1993)
Mikroreprod. eines Ms. Getr. Zählung : graph. Darst.
Rechnergestützte Simulation des Richtprozesses von Walzprofilen / (1987)
Knoll, Wolf-Dietrich., Wolf, Martin.
Magdeburg, Techn. Univ., Diss. A, 1987 (Nicht für den Austausch).
This article argues that “differential and more favourable treatment” of developing countries in the General Agreement on Tariffs and Trade (GATT) has been a logical consequence of their own...
Gütebewertung von Röntgenaufnahmen unter Berücksichtigung des Bildrauschens. (1981)
Berlin, Humboldt-Univ., Diss., 1981.
Gütebewertung von Röntgenaufnahmen unter Berücksichtigung des Bildrauschens. (1981)
Berlin, Humboldt-Univ., Diss., 1981.
Berlin (West), Techn. Univ., Fachbereich f. Landwirtschaftl. Entwicklung, Diss. Nr. 7, 1971.
Globalization and Global Economic Governance
This article focuses on the World Trade Organization (WTO) and the International Monetary Fund (IMF). It starts by noting that the case for creating such institutions is not self-evident, since the...
This paper compares the globalisation experience of the late 19-super-th century with that of the post world war period. It notes the enormous changes in the world economy arising from the increasing...
Globalization is not inevitable. It depends on politics. Today, it depends above all on US politics. Without successful US leadership, the present globalization may founder, just as the last one did....
"The view that the United States will be able to run significant deficits for a long time is convincing. However, the proposition that it makes sense for foreigners to invest in the USA because of...