Biographical Information

• PhD, The University of York, 2002
• Diplom Physik (MSc Physics), J.W. Goethe-Universitat Frankfurt, 1997

Honors and Awards

• Feodor-Lynen Fellow, Alexander von Humboldt Foundation, 2002-2004

Research Interests

Exploring Dynamics and Functionality of Biophotonic Molecules via Time-Resolved Spectroscopy

Biophotonic functions are triggered through light activation. The photoexcited biomolecules can undergo a variety of competing processes and the competition between these processes governs the selectivity, efficiency and reliability of their function. However, biophotonic molecules are not isolated and the local environment (e.g. solvent, protein shell) can have a large effect on dynamical processes. Nature can use specific intermolecular interactions to alter the energetic and dynamic properties of isolated building blocks thus the efficiency of a particular function can be enhanced with respect to undesired processes.

Our approach towards a molecular level understanding of biophotonic processes is to design time-resolved spectroscopic experiments in a controlled environment to distinguish between intrinsic and environmentally superimposed molecular properties. We use modern femtosecond and picosecond time-resolved pump-probe spectroscopies − both transient absorption and photoelectron photoion coincidence spectroscopy − to investigate dynamic biophotonic processes in the gas-phase, in molecular clusters, where the complexity of the environment can be varied, and in solution. Combined with ab initio calculations outcomes of our research include a molecular level understanding of biophotonic stability and the efficiency of biophotonic processes as well as molecular dynamics criteria for the rational design of novel biophotonic systems.

Ultrafast Spectroscopy of Thin Films and Nanomaterials

In this project we are using time-resolved transient absorption spectroscopy to investigate ultrafast processes and charge separation dynamics in materials relevant to photocatalysis and solar energy conversion.   

Power-generating windows and roofs, using silicon-based solar panels, are emerging in the commercial market, but their optical and mechanical properties, as well as cost, hinder widespread adoption. Thin-film organic solar cells and organic-inorganic hybrid perovskites solar cells have great potential for next-generation solar panels, because of their mechanical durability and flexibility, tunable transmission, high energy conversion efficiency, and low-cost production. Our current studies assess the suitability of novel perovskite-based solar cells as a clean, renewable energy source and its applications in greenhouses. 

We are also investigating copper oxides and related semiconductor materials which are attractive candidates for optoelectronic applications, including photovoltaics, photocatalysis, and all-optical switching.

Recent Publications

Hanna, E. Movsesian, M. Orozco, A. R. Bernot Jr., M. Asadinamin, L. Shenje, S. Ullrich, Y. Zhao, N. Marshall, J. A. Weeks, M. B. Thomas, J. A. Teprovich Jr., P. A. Ward: Spectroscopic Investigation of the Electronic and Excited State Properties of Para-Substituted Tetraphenyl Porphyrins and Their Electrochemically Generated Ions, Spectrochimica Acta Part A 2022, 278, 121300.

L. Shenje, Y. Qu, V. Popik, S. Ullrich: Femtosecond Photodecarbonylation of photo-Oxadibenzocyclooctyne Studied by Stimulated Raman Spectroscopy and Density Functional Theory. Phys. Chem. Chem. Phys. 2021, 23, 25637. Invited for themed collection “Ultrafast Spectroscopy: Theory and Experiments”.

L Shenje, W. Thompson, Z. Ren, N. Lin, V. Popik, S. Ullrich: Ultrafast transient absorption spectroscopy of the photodecarbonylation of photo-oxadibenzocyclooctyne (photo-ODIBO) Chem. Phys. 2021, 154, 074302. Invited for “Special Collection in Honor of Women in Chemical Physics and Physical Chemistry.”

L. Shenje, S. Larson, Y. Zhao, S. Ullrich: Composition Effects on Ultrafast Optical Properties of CuxOy Thin Films: A Transient Absorption Study. J. Phys. Chem. C 2020, 124, 24908-24918.

A. Mohamadzade, S.Ullrich: Internal conversion and intersystem crossing dynamics of Uracil upon double thionation: A time-resolved photoelectron spectroscopy study in the gas phase. Phys. Chem. Chem. Phys. 2020, 22, 15608.

G. Hastings, H. Makita, L. T. Shenje, S. Ullrich: Femtosecond Time-resolved Spectroscopy for the Study of Photosystem I Reaction Centers at 77 K. Frontiers in Science, Technology, Engineering and Mathematics, 2019, 3(2), 63-70. Front cover.

D. Cotten, N. Neel, M. Mishra, M. Madden, C. Adams, S. Ullrich, A. Burd, M. Adams, K. Summey, C. Versteeg, J. Parker, F. Beyette: The Spectral Ocean Color Imager (SPOC) - An Adjustable Multispectral Imager, Proceedings of the AIAA/USU Conference on Small Satellites, Pre-Conference Workshop Session VII: Instruments/Science II, SSC19-WKVII-03 2019.

S. Ullrich, A. Mohamadzade: Intersystem crossing dynamics in thionated uracils studied by time‐resolved photoelectron spectroscopy: The effect of substituent position, Conference Proceedings, International Conference on Ultrafast Phenomena, EPJ Web of Conferences, 2019, 205, 09010.

S. Mai, P. Marquetand, L. González, A. Mohamadzade, S. Ullrich: Simulated and Experimental Time-Resolved Photoelectron Spectra of the Intersystem Crossing dynamics in 2-Thiouracil. Molecules, 2018, 23, 2836. Invited contribution special issue: “Theoretical Excited-State Chemistry: New Developments and Cutting-Edge Applications”.

A. Mohamadzade, S. Bai, M. Barbatti, S. Ullrich: Intersystem crossing photodynamics of 4- thiouracil studied by time-resolved photoelectron spectroscopy, 2018, Chem. Phys., 2018, 515, 572. DOI: 10.1016/j.chemphys.2018.08.011.

C. McNitt, H. Cheng, S. Ullrich, V. Popik, M. Bjerknes: Multiphoton Activation of Photo-SPAAC ’Click’ Reagents Enables In-situ Labeling with Submicron Resolution, J. Amer. Chem. Soc., 2017, 139, 4029–14032.

J. A. Sánchez-Rodríguez, A. Mohamadzade,  S. Mai,  B. Ashwood,  M. Pollum,  P. Marquetand,  L. González,  C. E. Crespo-Hernández, S. Ullrich:  2-Thiouracil intersystem crossing photodynamics studied by wavelength-dependent photoelectron and transient absorption spectroscopies, Phys. Chem. Chem. Phys., 2017, 19, 19756-19766. 

H. Yu, J. A. Sanchez-Rodriguez, M. Pollum, C. E. Crespo-Hernández, S. Mai, P. Marquetand, L. González, S. Ullrich: Internal conversion and intersystem crossing pathways in UV excited, isolated uracils and their implications in prebiotic chemistry, Phys. Chem. Chem. Phys., 2016, 18, 20168-20176. 

T. J. Godfrey, H. Yu, M. S. Biddle, S. Ullrich: A Wavelength Dependent Investigation of the Indole Photophysics via Ionization and Fragmentation Pump-Probe Spectroscopies, Phys. Chem. Chem. Phys., 2015, 17, 25197-209.

H. Yu, N. L. Evans, A. S. Chatterly, G. M. Roberts, V. G. Stavros, S. Ullrich: Tunneling Dynamics of the NH₃ Ã-State Observed by Time-resolved Photoelectron and H-atom Kinetic Energy Spectroscopies. J. Phys. Chem. A, 2014, 118, 9438.

T. J. Godfrey, H. Yu, S. Ullrich: Investigation of electronically excited indole relaxation dynamics via photoionization and fragmentation pump-probe spectroscopy, J. Chem. Phys., 2014, 141, 044314.

G. M. Roberts, C. A. Williams, J. D. Young, A. S. Chatterley, H. Yu, S. Ullrich, V. G. Stavros: Probing Ultrafast Dynamics in Photoexcited Pyrrole: Timescales for 1πσ* Mediated H-atom Elimination, Faraday Discussions 163: Photo-initiated Quantum Molecular Dynamics, 2013, 163, 95.

G. M. Roberts, C. A. Williams, J. D. Young, S. Ullrich, M. J. Paterson, V. G. Stavros: Unraveling Ultrafast Dynamics in Photoexcited Aniline, J. Amer. Chem. Soc., 2012, 134, 12578.

N. L. Evans, H. Yu, G. M. Roberts, V. G. Stavros, S. Ullrich: Observation of Ultrafast NH3 (Ã) State Relaxation Dynamics using a Combination of Time-resolved Photoelectron Spectroscopy and Photoproduct Detection, Phys. Chem. Chem. Phys. 2012., 14, 10401.

H. Yu, N. L. Evans, V. G. Stavros, S. Ullrich: Investigation of Multiple Electronic Excited State Relaxation Pathways Following 200 nm Photolysis of Gas-phase Imidazole, Phys. Chem. Chem. Phys. 2012, 14, 6259.

G. M. Roberts, C. A. Williams, M. J. Paterson, S. Ullrich, V. G. Stavros: Comparing the ultraviolet photostability of azole chromophores, Chemical Sciences 2012, 3, 1192.

C. A. Williams, G. M. Roberts, H. Yu, N. L. Evans, S. Ullrich, V. G. Stavros: Exploring Ultrafast H-Atom Elimination versus Photofragmentation Pathways in Pyrazole Following 200 nm Excitation, J. Phys. Chem. 2012, 116, 2600.

R. Crespo-Otero, M. Barbatti, H. Yu, N. L. Evans, S. Ullrich: The ultrafast dynamics of UV-excited imidazole, ChemPhysChem 2011, 12, 3365.

M. Barbatti, S. Ullrich: Ionization potentials of adenine along the internal conversion pathways, Phys. Chem. Chem. Phys. 2011, 13, 15492.

N. L. Evans, S. Ullrich, C. J. Bennett, R. I. Kaiser: On the Interaction of Adenine with Ionizing Radiation – Mechanistical Studies and Astrobiological Implications, Astrophys. J. 2011, 730, 69.

N. L. Evans, S. Ullrich: Wavelength dependence of electronic relaxation in isolated adenine using UV femtosecond time-resolved photoelectron spectroscopy, J. Phys. Chem. A 2010, 114, 11225.

A. N. Brouillette, N. Evans, W. M. Potter, S. Ullrich: Time-resolved Photoelectron Spectroscopy and the Photoprotective Properties of Adenine, The Journal of Undergraduate Research in Physics, Volume 22, 2009.

C. Z. Bisgaard, H. Satzger, S. Ullrich, A. Stolow: Excited state dynamics of isolated DNA bases: A case study of Adenine, ChemPhysChem 2009, 10, 101. 

A. M. D. Lee, J. D. Coe, S. Ullrich, M.-L. Ho, S.-J. Lee, B.-M. Cheng, M. Z. Zgierski, I-C. Chen, T. J. Martínez, A. Stolow: Substituent effects on Dynamics at Conical Intersections: alpha,beta –enones, J. Phys. Chem. A 2007, 111, 11948.

H. R. Hudock, B. G. Levine, A. L. Thompson, H. Satzger, D. Townsend, N. Gador, S. Ullrich, A. Stolow, T. J. Martínez: Ab Initio Molecular Dynamics and Time-Resolved Photoelectron Spectroscopy of Electronically Excited Uracil and Thymine, J. Phys. Chem. 2007, 111, 8500.

H. Satzger, D. Townsend, M. Z. Zgierski, S. Patchkovskii, S. Ullrich, A. Stolow: Primary processes underlying the photostability of isolated DNA bases: adenine, PNAS 2006, 103, 10196.

E. Samoylova, H. Lippert, S. Ullrich, I.V. Hertel, W. Radloff, T. Schultz: Dynamics of photoinduced processes in adenine and thymine base pairs, J. Amer. Chem. Soc. 2005, 127, 1782.

S. Ullrich, T. Schultz, M.Z. Zgierski, A. Stolow: Electronic relaxation mechanism in DNA and RNA bases studied by time-resolved photoelectron spectroscopy, Phys. Chem. Chem. Phys. 2004, 6, 2796. 

S. Ullrich, T. Schultz, M.Z. Zgierski, A. Stolow: Direct observation of electronic relaxation dynamics in adenine via time-resolved photoelectron spectroscopy, J. Amer. Chem. Soc., Communication 2004, 126, 2262