Selected project descriptions

Descriptions, references, and contacts for specific open projects in the CMI group.

To apply for any of these positions, please send your application package, including scientific CV, list of publications, and letters of recommendation, to jochen.kuepper@cfel.de.

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Aerosols into vacuum

This project will develop strategies to optimally transfer large molecules/particles into high-vacuum through nebulization techniques, possibly combined with aerodynamic transport and focusing. Techniques include gas-dynamics-virtual-nozzle thin water jets, electrospray, and other analytical chemistry nebulization techniques, which will be combined with special aerodynamic lenses currently being developed in our group. This includes methodologies to cryogenically cool the produced beams. The resulting (bio)particle beams will be thoroughly characterized (density, distribution, charge-state, ...) and applied in fundamental physics and biochemistry/structural biology studies. Subsequently, the experiments will be extended toward the control of these beams (mass selection, isomer separation, angular alignment).

The well-controlled cold samples of large molecules/nanoparticles produced will be investigated using femtosecond lasers and with x-ray or electron diffraction experiments, using table-top (laboratory) as well as at Free-Electron laser sources.

The successful candidate will have an outstanding Ph.D. in experimental physics, physical chemistry, or a related field. Experience with aerosol technologies, lasers, vacuum equipment, or diffractive imaging is highly desirable.

Aerosol Sci. Technol. 22, 314 (1995)
Struct. Dyn. 2, 041717 (2015)
Opt. Exp., accepted (2016), arxiv:1512.06231 (2015)

Contacts: Dr. Daniel Horke, Prof. Dr. Jochen Küpper
Funding: ERC COMOTION, DESY

Control of aerodynamically focussed beams of very large molecules and nanoparticles

In this project we develop strategies to control the transfer of very large molecules and nanoparticles to the interaction point of modern imaging experiments, in high-vacuum, through the use of cryogenic techniques and optical manipulation. "Shock-freezing" the molecules makes them especially amenable to the control of their internal and external degrees of freedom. External electric and laser fields allow for precise steering of the particles as well as for spatial separation based on physical properties (size, mass, structure). Methodologies to characterize these beams regarding density, distribution, charge-state, etc will be further developed.

The well-controlled cold samples of very large molecules/nanoparticles produced will be investigated using X-ray or electron diffraction experiments in laboratory experiments, as well as at Free-Electron lasers.

The successful candidate will have an outstanding Ph.D. in experimental physics, physical chemistry, or a related field. Experience with lasers, aerosol technologies, vacuum equipment, or imaging is highly desirable.

Opt. Exp. 21, 30492 (2013)
Phys. Rev. X 2, 031002 (2012)
Int. Rev. Phys. Chem. X 34, 557 (2015)
Phys. Rev. Applied 4, 064001 (2015)
Opt. Expr., accepted (2016), arXiv:1512.06231 (2015)

Contacts: Dr. Daniel Horke, Prof. Dr. Jochen Küpper
Funding: ERC COMOTION, DESY

Cryogenic buffer-gas cooling of bio-molecules and nanoparticles

In this ERC-funded project we will develop strategies to cryogenically shock-freeze large molecules and nanoparticles, ranging from model peptides to entire viruses. This involves the setup of a cryogenic buffer-gas cell and its coupling to various vaporization and particle sources available or in development in our group (e.g., liquid jets, aerodynamics lenses, electrospray, etc.). The resulting cold samples will be thoroughly characterized (density, distribution, shape, isomer, etc.) and applied in fundamental physics and biochemistry/structural biology studies within the ERC-Consolidator-Grant funded project COMOTION.

The well-controlled cold samples of large molecules and nanoparticles produced will be investigated using femtosecond lasers and they will be applied in x-ray and electron diffraction experiments, using table-top (laboratory) as well as at free-electron-laser sources.

The successful candidate will have an excellent PhD in physical chemistry, molecular physics, or a related field. Experience with cryogenics, particle imaging, high-vacuum equipment, and pulsed lasers is highly desirable.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Center for Ultrafast Imaging.

Nature 470, 78 (2011)
Annu. Rev. Phys. Chem. 64, 415 (2013)
Struct. Dyn. 2, 041717 (2015)
Int. Rev. Phys. Chem. 34, 557 (2015)
Opt. Express 24, 6507 (2016)

Contacts: Dr. Daniel Horke, Prof. Dr. Jochen Küpper
Funding: ERC COMOTION, DESY

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Electrospray nebulization for atomic resolution single-particle imaging

In this ERC-funded PhD project strategies to transfer large molecules/particles into high-vacuum using electrospray nebulization techniques will be developed. These aerosol sources will be combined with special aerodynamic lenses and cryogenic buffer-gas cells currently being developed in our group, to produce collimated and cold beams of (biological) particles in the gas-phase. The resulting particle beams will be thoroughly characterized (density, distribution, charge-state, shape, isomer, etc.) and applied in fundamental physics and biochemistry/structural biology studies within the ERC-Consolidator-Grant funded project COMOTION.

The produced and well-controlled cold samples of large molecules and nanoparticles will be investigat- ed using femtosecond lasers and they will be applied in x-ray and electron diffraction experiments, using table-top (laboratory) as well as at free-electron-laser sources.

The successful candidate will have a strong background in physical chemistry, molecular physics, or a related field. Experience with aerosol generation, particle imaging, high-vacuum equipment, and pulsed lasers is a plus.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Center for Ultrafast Imaging.

Nature 470, 78 (2011)
Annu. Rev. Phys. Chem. 64, 415 (2013)
Struct. Dyn. 2, 041717 (2015)
Int. Rev. Phys. Chem. 34, 557 (2015)
Opt. Express 24, 6507 (2016)

Contacts: Dr. Daniel Horke, Prof. Dr. Jochen Küpper
Funding: ERC COMOTION, DESY

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Imaging and optimizing coherent nanotip-array electron sources

We are working, jointly with the group of Franz Kärtner at CFEL, on measuring the electron emittance from single nanotips and nanotip arrays using an imaging spectrometer (VMI) through spatial-map and velocity-map imaging in order to characterize and optimize the electron packets from nanotip arrays. These ultrashort electron bunches could be used for ultrashort-pulse electron diffraction as well as for the realization of a tabletop coherent Inverse Compton Scattering hard-X-ray source.

The successful candidate will have an outstanding Ph.D. in experimental physics, physical chemistry, or a related field. Experience with velocity-map imaging, short-pulse lasers, or vacuum equipment is highly desirable.

Ultrafast Phenomena XIX, Springer Proceedings in Physics 162, 663 (2015)
J. Phys. B 48, 244001 (2015)

Contacts: Dr. Sebastian Trippel, Prof. Dr. Jochen Küpper
Funding: The Hamburg Center for Ultrafast Imaging (CUI)

Unraveling chemical dynamics through diffractive imaging

Modern experimental approaches allow for the diffraction imaging of chemical dynamics using x-ray free-electron lasers or high-power table-top lasers. In combination with our methodologies to control molecular samples these promise unprecedented experimental details of the chemical dynamics of complex molecules. The goal of this project is to disentangle the structure-function relationship of conformer-specific chemical dynamics and of folding-type rearrangements of model peptides through time-resolved x-ray- and electron-diffractive imaging.

The project requires significant organizational work in preparation of large-collaboration beamtimes and a strong overview of experimental and theoretical developments in the field and beyond.

The successful candidate will have an outstanding Ph.D. in experimental physics, physical chemistry, or a related field. Experience with, at least some of, diffractive imaging concepts, complex molecules in the gas-phase, free-electron and table-top lasers, or vacuum equipment is highly desirable

Phys. Rev. Lett. 112, 083002 (2014)
J. Phys. B, 48, 244001 (2015)
Int. Rev. Phys. Chem., 34, 557 (2015)

Contacts: Prof. Dr. Jochen Küpper
Funding: ERC COMOTION or HGF/DESY

Ultrafast electron dynamics in complex molecules

To see the chemistry, you have to follow the electrons. Indeed, it is becoming evident that one has to study the combined electronic and nuclear dynamics of molecules in order to understand the elementary steps of chemical dynamics. Based on previous and current molecular-frame-photoelectron-angular-distribution-imaging experiments performed in our group we are preparing for experiments to image ultrafast dynamics in complex molecules. These experiments are targeted at the disentangling of ultrafast electronic dynamics coupled to femtosecond nuclear dynamics.

The successful candidate will have an outstanding Ph.D. in experimental physics, physical chemistry, or a related field. Extensive experience with ultrashort-pulse lasers is required; experience with few-femtosecond laser pulses, ultra-high-vacuum equipment, or electron imaging is a bonus.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Center for Ultrafast Imaging.

Phys. Rev. Lett. 102, 023001 (2009)
Nat. Phys. 6, 428 (2010)
Phys. Rev. Lett. 114, 103003 (2015)
Phys. Rev. A. 94, 013412 (2016)

Contacts: Dr. Sebastian Trippel, Prof. Dr. Jochen Küpper

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Structure-function relationship in “cold” chemical reactions

We are investigating the structure-function relationship of conformer-selected complex molecules. In collaboration with the Willitsch group in Basel we have performed pioneering benchmark experiments to investigate structure-dependent chemical reactivities (see Science paper below). These experiments are now being extended to the investigation of conformer-separated molecule-molecule reactions.

In this project the candidate will extend our benchmark studies to the investigation of conformer specific reactivity studies of complex chemical reactions, such as cycloadditions (Diels-Alder reactions) and other textbook examples, in order to disentangle the microscopic details. This involves the experimental verification of relevant molecular properties in deflection and spectroscopy experiments, and the measurement of conformer specific reactivities. Moreover, the detailed analysis requires programming simulations of the deflection process, and quantum-chemistry calculations. This project will involve repeated travel to our collaborators at the University of Basel, Switzerland.

A successful candidate will have a strong background in physical chemistry, molecular physics, or a related field. Experience with molecular beams, high-vacuum equipment, short-pulse lasers or quantum-chemistry codes is a plus.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Center for Ultrafast Imaging.

Science, 342, 98–101 (2013)
Phys. Rev. Lett. 100, 133003 (2008)
Angew. Chem. Int. Ed. 48, 4900 (2009)

Contacts: Prof. Dr. Jochen Küpper
Funding: HGF/DESY

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Structure-function relationship in chemical reactions using controlled molecules and cold ions

We are investigating the structure-function relationship of conformer-selected complex molecules. In collaboration with the Willitsch group in Basel we have performed a pioneering benchmark experiment to investigate structure-dependent chemical reactivities. We have determined the conformer-specific rate constants for the reactions of cis- and trans-3-aminophenol with Ca+ ions localized in a so called Coulomb Crystal. These experiments are now being extended to investigations of conformer-separated molecule-molecule reactions.

In this project the candidate will extend our benchmark studies to the investigation of conformer specific reactivity studies of complex chemical reactions, such as cycloadditions (Diels-Alder reactions) and other textbook examples, in order disentangle the microscopic details. This involves the experimental verification of relevant molecular properties in deflection and spectroscopy experiments, and the measurement of conformer specific reactivities. Moreover, detailed analysis requires programming simulations of the deflection process, and quantum-chemistry calculations. This project will involve repeated travel to our collaborators at the University of Basel, Switzerland.

A successful candidate will have a strong background in physical chemistry, molecular physics, or a related field.

Science, 342, 98–101 (2013)
Phys. Rev. Lett. 100, 133003 (2008)
Angew. Chem. Int. Ed. 48, 4900 (2009)

Contacts: Prof. Dr. Jochen Küpper
Funding: HGF/DESY

Computer science and ICT related projects

The following projects all possible as Bachelor or Masters thesis as well as in internships; further projects are available and can be assigned based on discussions, current needs, and you wishes for specific contributions.

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Graphical user interface design for Controlled Molecule Imaging controls and data acquisition

CMIdaq is a new implementation of a distributed controls and data acquisition system for Controlled Molecule Imaging experiments. The system is based on Tine and developed in Python and Qt. Hardware includes high-speed high-resolution cameras, fast digitizers and oscilloscopes, timing distribution and time delay electronics, motors for many different pieces of equipment, various laser sources, Linux, Windows, and Mac OS X computers, etc. Data handling and storage includes the use of gpfs (IBM Spectrum Scale) and dCache.

In this project, a modern, user-friendly, flexible, yet easy to use graphical user interface shall be designed and developed. This includes the implementation of modern UI concepts, versatile online analysis tools, data storage and documentation tools, and an analysis of user feedback.

Contacts: Prof. Dr. Jochen Küpper

Computation framework development of optically controlled particles experiments

These novel experimental approaches are supported by computational simulations based on classical trajectory calculations in combined electric and laser fields. To allow for the simulation of optical manipulation of nano-objects and very large biological objects, such as viruses or protein complexes, we are extending our computation suite to include new models of the underlying physics as well as the experimental apparatus used.

We offer an undergraduate thesis project to extend our simulation framework CMIfly and to implement new-physics descriptions in the simulation codes.

A successful candidate will have a strong background in modern software development. Experience in physics, hydrodynamics, and optics as well as in numerical methods is a plus.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Center for Ultrafast Imaging.

J. Chem. Phys. 131, 064309 (2009))
Int. Rev. Phys. Chem. 34, 557 (2015)
IPhys. Rev. Applied 4, 064001 (2015)

Contacts: Prof. Dr. Jochen Küpper

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Parallelization of quantum-physics code

We are developing a general-purpose code for the description to the rotational motion of arbitrarily complex molecules in electric and laser fields. The code implements a numerical solution to the time-dependent Schrödinger equation of the system considering all relevant symmetries. Typical runtimes for complex molecules in strong fields are many CPU months.

Here, an efficient and general parallelization shall be implemented. In the first step, this should be done through a multithreading approach, partly using multithreaded BLAS routines and partly by direct manual parallelization at higher levels. Further steps include message-passing parallelization across compute nodes as well as GPU-based acceleration.

The quantum-physics developments of the code are performed in close collaboration with Rosario González Férez at the Universidad de Granada. See CMIstark for a implementation of a time-independent dc-electric-field-only subset of the problem.

Contacts: Prof. Dr. Jochen Küpper

Parallelization of computation for simulations of molecule-control experiments

The Controlled Molecule Imaging group at the Center for Free-Electron Laser Science at DESY and University of Hamburg performs novel experiments on the control and imaging of gas-phase molecules and their intrinsic ultrafast dynamics. We develop unique experimental approaches to record movies of molecules at work.

These novel experimental approaches are supported by computational simulations based on solutions of the time-dependent Schrödinger equation. To increase the accessible molecular complexity in these simulations we are implementing and improving parallelized solvers in our codes.

We offer a bachelor thesis project to perform an extended runtime analysis and implement corresponding performance improvements and significant parallelization of our TDasyrot program suite.

A successful candidate will have a strong background in modern software development. Experience in quantum physics, numerical methods, and massive parallelization are a plus.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Centre for Ultrafast Imaging.

Phys. Rev. Lett. 102, 023001 (2009)
Comp. Phys. Comm. 185, 339 (2014)
Phys. Rev. Lett. 114, 103003 (2015)

Contacts: Prof. Dr. Jochen Küpper

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Flying molecules through electric fields

In this project a next-generation particle trajectory simulator shall be developed. Based on experience from two earlier codes to describe trajectories on particles through electric fields, we wish to implement a general purpose computational framework and user interface to describe the motion of large numbers of molecules and particles through laser and electric fields. From a physics point of view, various different interactions between the molecules and particles have to be included; sometimes taking care of the back-action of the particle on the field. Moreover, particle-particle interactions as well as particle-background interactions are relevant in certain cases.

This code forms the heart of the modeling of our control experiments and is of greatest importance for the prediction of future experiments and experimental setups. Furthermore, computation times can be very high and efficient use of resources (CPU, memory), parallelization, and appropriate approximations need to be implemented.

Contacts: Prof. Dr. Jochen Küpper

Data Acquisition and Control for novel physics experiments

The Controlled Molecule Imaging group at the Center for Free-Electron Laser Science at DESY and University of Hamburg performs novel experiments on the control and imaging of gas-phase molecules and their intrinsic ultrafast dynamics. We develop unique experimental apparatus to record movies of molecules at work.

Novel experimental setups require new software to control equipment, acquire data, and analyze the obtained results. To strengthen our team we are looking for software developers with a background in experiment controls, data acquisition, and online analysis — or the desire to apply modern programming concepts to these important and challenging applications.

A successful candidate will have a strong background in modern software development and hardware programming. Experience in experimental physics or related scientific environments is a plus but not necessary. The position can be filled at various levels.

We offer unique research opportunities in an interesting and open team and with first-class experimental and computational facilities. Our group is embedded in the Center for Free-Electron-Laser Science, DESY, the University of Hamburg and the excellence cluster Hamburg Centre for Ultrafast Imaging.

Phys. Rev. Lett. 100, 133003 (2008)
Phys. Rev. Lett. 102, 023001 (2009)
Angew. Chem. Int. Ed. 48, 4900 (2009)
Nature Phys. 6, 428 (2010)
Science 342, 98–101 (2013)
Phys. Rev. Lett. 114, 103003 (2015)

Contacts: Prof. Dr. Jochen Küpper

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