Renske van der veen thesis proposal

Assistant Professor of Chemistry

Professor van der Veen acquired her B.S. and M.S. levels in Chemistry in the Swiss Federal Institute of Technology (ETH) in Züwealthy in the year 2006. This Year she received her Ph.D. in the area of ultrafast X-ray science in the École Polytechnique Fédérale de Lausanne (EPFL) and also the Swiss Source Of Light. We have spent like a postdoctoral fellow in the California Institute of Technology, she grew to become a task group leader in the Max Planck Institute for Biophysical Chemistry in Göttingen. She became a member of the College of Illinois faculty being an Assistant Professor in April 2015, and it is associated with the Ernest Seitz Materials Research Laboratory and also the Materials Science and Engineering Department. She’s thinking about study regarding atomic-scale mechanisms of sunshine-caused processes, for example photoswitching, photovoltaics and photocatalysis.

Research

The conversion of sunshine energy into chemical energy is really a subject of uttermost importance nowadays. One of the general goals would be to develop materials that may efficiently convert and store the sun’s energy, or nanomaterials that may be quickly switched between two states letting them be utilized in data storage devices. A simple knowledge of the photophysical processes involved with light-energy conversion is prerequisite for developing such new materials with preferred qualities.

In this particular context, our research concentrates on several kinds of light-sensitive (molecular) materials: (i) switchable metal-organic complexes, (ii) functional nanomaterials highly relevant to photocatalysis, and (iii) photovoltaic perovskite materials. We wish to know how the power found in a photon is channeled onto pathways and into states you can use for particular functions.

How quickly and efficient are excited-condition relaxation processes and just how do electronic and structural levels of freedom couple?

To tackle these questions, we employ a number of ultrafast spectroscopic and microscopic methods as time passes resolutions varying from femtoseconds (fs) to nanoseconds (ns).

(1) Ultrafast Optical Spectroscopy and Microscopy

Optical spectroscopy within the Ultra violet-visible spectral range is principally responsive to the occupation and of valence orbitals near to the Fermi level. Transient absorption spectroscopy with

100 fs time resolution can be used to follow along with the power relaxation processes upon excitation into well-defined absorption bands via metal-to-ligand charge-transfer (MLCT), metal- or ligand-centered transitions. By interfacing transient absorption spectroscopy having a laser-checking confocal microscope, we’ll study relaxation processes in nanoscale materials, for example nanoparticles and thin films.

(2) Ultrafast X-ray Spectroscopy in particular-Scale Facilities

The transformation of spectroscopic observables within the Ultra violet-visible range into bond distances requires detailed understanding concerning the potential energy surfaces from the states involved. Although this is obvious for small molecules, it might be more ambiguous once the system grows in complexity and size, e.g. when solute-solvent interactions come up. To be able to overcome these difficulties, we use probing methods according to high-energy radiation (X-sun rays) or particles (electrons) to probe the systems under study.

Our prime energy entails a brief wave length which is often used to get the preferred atomic-spatial resolution, without involve a priori understanding about potential energy surfaces.

X-ray absorption spectroscopy (XAS) is especially appealing for study regarding (metal-organic) molecular materials, because it is a nearby probe of both electronic and geometric structure, also it can be implemented in almost any medium. Within our lab, we use short (fs-ps) X-ray pulses from synchrotron radiation facilities or X-ray free-electron lasers (XFEL) to probe the dynamics after excitation having a fs laser pulse. Dedicated computer codes are widely-used to simulate and fit the X-ray spectra to be able to extract the excited-condition dynamics.

(3) Ultrafast Electron Microscopy

We exploit our prime spatial and temporal resolutions of ultrafast electron microscopy (UEM) to show the electronic and structural dynamics of nanostructured materials. When compared with ultrafast optical and X-ray methods, UEM exhibits an excellent spatial imaging resolution (sub-nm), also it provides the possible ways to characterize morphology (via imaging), geometric structure (via diffraction), and electronic structure (via spectroscopy, EELS) of materials – all inside the same table-top setup.

UEM has become just as one more and more attractive tool that mixes the atomic-scale spatial resolution of conventional TEM, using the high temporal (fs-ns) resolution of optical spectroscopy. The key of UEM is dependant on the generation of ultrashort electron pulses while using photoelectric effect in the cathode. Reversible excited-condition processes could be studied in stroboscopic mode at high repetition rates, while irreversible processes are probed by single-shot and movie-mode recognition.

The UEM machine which is used within our lab is presently being developed in the Ernest Seitz Materials Research Laboratory together with the audience of Prof. Jian-Min Zuo.

Publications

For any full publication list see

• R.M. van der Veen. T.J. Penfold, A.H. Zewail, “Ultrafast Core-Loss Spectroscopy in 4D Electron Microscopy”, Posted (Jan. 2015)
• G.M. Vanacore, R.M. van der Veen. A.H. Zewail, “Origin of Axial and Radial Expansions in Carbon Nanotubes Revealed by Ultrafast Diffraction and Spectroscopy”, ACS Nano9 (2), 1721–1729 (2015)
• R.M. van der Veen. A. Tissot, A. Hauser, A.H. Zewail, Unusual Molecular Material created through Irreversible Transformation and revealed by 4D Electron Microscopy, Phys. Chem. Chem. Phys. 15. 7831-7838 (2013)
• R.M. van der Veen. O-H. Kwon, S.T. Park, A. Tissot, A. Hauser, A.H. Zewail, Single-Nanoparticle Phase Transitions Visualized by 4D Electron Microscopy, Nature Chem. 5. 395-402 (2013)
• A. Yurtsever, R.M. van der Veen. A.H. Zewail, Sub-particle Ultrafast Spectrum Imaging in Electron Microscopy, Science335. 6064 (2012)
• V.-T. Pham, T. Penfold, R.M. van der Veen. C.J. Milne, A. ElNahhas, F.A. Lima, S.L. Manley, R. Abela, I. Tavernelli, C. Bressler and M. Chergui, Probing the transition from hydrophilic to hydrophobic solvation with atomic scale resolution, J. Am. Chem. Soc.133 (32), 12740-12748 (2011)
• R.M. van der Veen. A. Cannizzo, F. van Mourik, A. Vlek Junior. and M. Chergui, Vibrational wavepacket dynamics and intersystem crossing in binuclear metal complexes in solution, J. Am. Chem. Soc. 133 (2), 305-315 (2011)
• M. Herzog, R. Shayduk, W. Leitenberger, R.M. van der Veen. S. Manley, Ch. Milne, I. Vrejoiu, M. Alexe, D. Hesse and M. Bargheer, Ultrafast manipulation of hard X-sun rays by efficient Bragg switches, Appl. Phys. Lett. 96. 161906 (2010)
• R.M. van der Veen. J.J. Kas, C.J. Milne, V.-T. Pham, A. El Nahhas, F.A. Lima, D.A. Vithanage, J.J. Rehr, R. Abela and M. Chergui, L-edge XANES analysis of photoexcited metal complexes in solution, Phys. Chem. Chem. Phys.12. 5551-5561 (2010) (asked article)
• R.M. van der Veen. C.J. Milne, V.-T. Pham, A. El Nahhas, J. Best, J.A. Weinstein, C.N. Borca, R. Abela, C. Bressler and M. Chergui, Structural resolution of a photochemically reactive diplatinum molecule by time-resolved EXAFS spectroscopy, Angew. Chem. Int. Erectile dysfunction.48 (15), 2711-2714 (2009) (rated as Essential Paper)
• W. Gawelda, V.-T. Pham, R.M. van der Veen. D. Grolimund, R. Abela, M. Chergui and C. Bressler, Structural analysis of ultrafast EXAFS with sub-picometer spatial resolution: application to solvated spin mix-over complexes, J. Chem. Phys.130 (12), 124520 (2009)
• R.M. van der Veen. C. Bressler, C.J. Milne, V.-T. Pham, A. El Nahhas, F.A. Lima, W. Gawelda, C.N. Borca, R. Abela and M. Chergui, Retrieving photochemically active structures by time-resolved EXAFS spectroscopy, J. Phys. Conf. Ser.190 012054 (2009)
• C. Bressler, C.J. Milne, V.-T. Pham, A. El Nahhas, R.M. van der Veen. S.L. Manley, P. Beaud, A. Hauser, D. Grolimund and M. Chergui, Femtosecond XANES from the photocycle of Iron(II) Molecular complexes, Science323. 489 (2009)
• R.M. van der Veen. C.J. Milne, V.-T. Pham, A. El Nahhas, J.A. Weinstein, J. Best, C.N. Borca, C. Bressler and M. Chergui, EXAFS structural resolution of the Pt2(P2O5H2)44- anion, CHIMIA62 (4) 287-290 (2008) (asked article)
• H.-J. Wörner, R. van der Veen and F. Merkt, Jahn-Teller effect within the methane cation: rovibronic structure and also the geometric phase, Phys. Rev. Lett.97. 173003 (2006)

Awards

• Sofja Kovalevskaja Award from the Alexander von Humboldt Foundation (April 2014)
• Independent Max Planck Group Leader position hired through the President from the Max Planck Society (March 2014)
• Special mention within the EPFL Doctoral Award election (April 2012)
• Prospective Investigator Fellowship from the Swiss National Science Foundation (April 2010)
• Swiss Chemical Society prize to find the best poster talk in Physical Chemistry, SCS Fall Meeting, Lausanne (Sept. 2007)
• Doctorate fellowship awarded through the Doctorate School of Photonics, EPFL (November. 2006)

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