Structural and multi-dimensional spectroscopy of atoms and molecules on ultrafast time scales using CEP-controlled few-cycle light fields and (continuum-continuum) high-harmonic generation
Final Report Abstract
The interaction of strong laser fields with matter represents a major challenge to our physics understanding. At the same time, such laser fields are exquisite tools in the engineering of matter down to the atomic scale, where it promises applications such as high-fidelity (superposition) state preparation on the fundamental scientific side as well as the control of chemical reactions and easy access to novel molecular compounds on the applied side. Here in this project, we focused on strong-field responses of matter and their access by novel spectroscopy approaches to understand structure and dynamics from small to large quantum systems. To that end, novel multidimensional spectroscopy schemes were developed for atoms and generalized for molecules. For helium atoms, we learned in the doctoral work of Alexander Blättermann that the timedelay dependent strong-field-controlled polarization response can be understood in a twodimensional spectral representation. From this representation resonant and non-resonant strong-field coupling of excited states can be extracted. To do so, the dipole-control model (DCM) was developed which immediately afterwards could be directly used to measure the shape properties of the strong-field laser pulses. It thus provides an in-situ characterization of such strong-field absorption experiments which in the future will enable strong-field measurements and benchmarking of quantum-dynamics models on an entirely new level of precision. Surprisingly, the modification of dipoles by strong laser fields was also found to be accessible in large molecules in solution. Despite spectrally overlapping resonances creating broad absorption bands in the complex vibronic excited-state landscape, it was possible to explain the intensity-dependent modifications in the 2-dimensional absorption spectra at a given time delay (control pulse acting after an excitation pulse) by a simple model: A levelspecific coupling constant that leads to time- and intensity-dependent phase shifts on the quantum states and thus their modified dipole response accessible in the laser spectrum. The opportunity to perform such quantitative strong-field quantum control in complex molecules in solution is an important stepping stone towards comprehensive coherent control of chemistry. Accordingly, this result has led to public attention and press releases in the portals Pro-Physik.de (http://www.prophysik.de/details/news/8689051/Molekulare_Saiten_zum_Schwingen_gebracht.html) and Chemie.de (http://www.chemie.de/news/156047/molekulare-saiten-zum-schwingengebracht-und-neu-gestimmt.html). In addition, also within the course of this project, an all-reflective monolithic 2-dimensional spectroscopy setup based on a four-quadrant split mirror has been successfully designed, implemented and used for experiments. With this device XUV-XUV degenerate follow-on experiments at free-electron lasers are currently in planning and first successful preliminary results have recently been obtained in an XUV-XUV transient absorption experiment at FLASH.
Publications
- Carrier-envelope phase-and spectral control of fractional high-harmonic combs, Journal of Applied Physics 114, 12, 173102 (2013)
P. Raith, C. Ott, K. Meyer, A. Kaldun, M. Laux, M. Ceci, C. P. Anderson, and T. Pfeifer
(See online at https://doi.org/10.1063/1.4827194) - Passively phase-stable, monolithic, all-reflective two-dimensional electronic spectroscopy based on a four-quadrant mirror, Opt. Lett. 38, 356 (2013)
Y. Z. Zhang, K. Meyer, C. Ott, and T. Pfeifer
- Extracting Phase and Amplitude Modifications of Laser-Coupled Fano Resonances, Phys. Rev. Lett. 112, 103001 (2014)
A. Kaldun, C. Ott, A. Blättermann, M. Laux, K. Meyer, T. Ding, A. Fischer, and T. Pfeifer
(See online at https://doi.org/10.1103/PhysRevLett.112.103001) - Reconstruction and control of a time-dependent two-electron wave packet, Nature 516, 374 (2014)
C. Ott, A. Kaldun, L. Argenti, P. Raith, K. Meyer, M. Laux, Y. Zhang, A. Blättermann, S. Hagstotz, T. Ding, R. Heck, J. Madroñero, F. Martin, and T. Pfeifer
(See online at https://doi.org/10.1038/nature14026) - Two-dimensional spectral interpretation of time-dependent absorption near laser-coupled resonances, J. Phys. B: At., Mol. Opt. Phys. 47, 124008 (2014)
A. Blättermann, C. Ott, A. Kaldun, T. Ding, and T. Pfeifer
(See online at https://doi.org/10.1088/0953-4075/47/12/124008) - In situ characterization of few-cycle laser pulses in transient absorption spectroscopy, Opt. Lett. 40, 3464 (2015)
A. Blättermann, C. Ott, A. Kaldun, T. Ding, V. Stooß, M. Laux, M. Rebholz, and T. Pfeifer
(See online at https://doi.org/10.1364/OL.40.003464) - Signatures and control of strong-field dynamics in a complex system, Proc. Natl. Acad. Sci. USA 112, 15613 (2015)
K. Meyer, Z. Liu, N. Müller, J.-M. Mewes, A. Dreuw, T. Buckup, M. Motzkus, and T. Pfeifer
(See online at https://doi.org/10.1073/pnas.1509201112) - Time-resolved four-wave-mixing spectroscopy for inner-valence transitions, Opt. Lett. 41, 709 (2016)
T. Ding, C. Ott, A. Kaldun, A. Blättermann, K. Meyer, V. Stooß, M. Rebholz, P. Birk, M. Hartmann, A. Brown, H. Van Der Hart, and T. Pfeifer
(See online at https://doi.org/10.1364/OL.41.000709)
