The Krich group in the Department of Physics at the University of Ottawa is hiring a postdoctoral fellow for up to 2 years, performing theoretical work on intensity-dependent nonlinear spectroscopies. Applications will be accepted until the position is filled.

The hired candidate will pursue extensions of work recently published in Nature [1], which demonstrated the separation of orders of nonlinear response in transient absorption (TA) spectroscopy. This position is based in Ottawa and will be in close collaboration with the experimental group of Tobias Brixner in Würzburg, Germany. The University of Ottawa is a vibrant centre of photonics research with an expanding emphasis on multidimensional spectroscopies.

Spectroscopy is often performed with weak incident light pulses, so each molecule absorbs either zero or one photons of light. As pulse intensities increase, some molecules interact with two (or more) photons, enabling the study of interactions between excitations, encoded in the molecules’ higher-order responses. Such experiments, however, are often hard to interpret, as they also contain responses from molecules that interacted with only one photon. We recently introduced a method, which we call “intensity cycling,” that overcomes this problem and allows the orders of response in TA spectroscopy to be systematically separated using carefully chosen pump pulse intensities [1,2,3]. The higher-order responses contain valuable information [4], including information about the per-encounter probability of exciton-exciton annihilation [1].

This project will develop intensity-dependent spectroscopic methods to separate orders of response in new forms of spectroscopy, including both coherent- and fluorescence-detected multidimensional spectroscopies. We will derive the methods and guide experiments in choosing intensities optimally. We will further develop understanding of the information content of the high-order responses. We will simulate spectra related to the experimental systems, using our Ultrafast Spectroscopy Suite [5] and/or methods brought or developed by the candidate.

The successful candidate will have a PhD in physics, chemistry, or a related field with a strong background in the theory of spectroscopy or quantum dynamics. Applications from those with an experimental background are welcome, but strong interest and proficiency in analytical and numerical modelling is required. Proficiency with programming (in any language) is desirable.

The Krich group fosters a culture of respect, teamwork, and inclusion, where collaboration, innovation, and creativity fuel our research excellence. All qualified persons are invited to apply, and we welcome applications from qualified Indigenous persons, racialized persons, persons with disabilities, women, and 2SLGBTQ+ persons. We are committed to working with applicants with disabilities requesting accommodation during the recruitment, assessment, and selection processes.

Interested applicants should send their cv and arrange for two references to be sent to Jacob Krich, jkrich@uottawa.ca.

Please forward this information to anyone who may be interested, and feel free to contact Jacob with questions.

I am also seeking graduate students at either MSc or PhD level to work on this and related projects.

[1] Malý, Lüttig, Rose, Turkin, Lambert, Krich, Brixner. Separating single- from multi-particle dynamics in nonlinear spectroscopy, Nature 616 280−287 (2023).
[2] Lüttig, Rose, Malý, Turkin, Bühler, Lambert, Krich, Brixner. High-order pump–probe and high-order two-dimensional electronic spectroscopy on the example of squaraine oligomers, Journal of Chemical Physics 158 234201 (2023).
[3] Lüttig, Mueller, Malý, Krich, Brixner. Higher-order multidimensional and pump–probe spectroscopies, Journal of Physical Chemistry Letters 14 7556 (2023).
[4] Rose and Krich, Interpretations of high-order transient absorption spectroscopies, Journal of Physical Chemistry Letters 14 10849 (2023).
[5] github.com/peterarose/ufss

Posted: 13 September 2024