Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
Department Seminar
Host: Alexander Paarmann

Friday, November 18, 2022, 11:00 am
All are invited to meet around 10:40 am for a chat with coffee & cookies.
PC Seminar Room, G 2.06, Faradayweg 4
Niclas Sven Mueller
University of Cambridge
Collective States in Self-assembled Nanomaterials for New Functionalities in Vibrational Spectroscopy and Light-matter Coupling
Collective states are key to understand properties of materials across different length scales. In my talk, I will give an overview of different functionalities that emerge from collective states, with prospects for vibrational spectroscopy and engineering material properties with light.
In the first part, I will show how we detect collective infrared vibrations in molecular monolayers with visible Raman spectroscopy [1]. This can be used to monitor Å distances of molecules with millisecond time resolution and to track photochemical reactions. I will then introduce collective plasmon polaritons in layered gold nanoparticle films as substrates to combine infrared and visible vibrational spectroscopy [2-4]. This allows us to measure vibrational lifetimes with IR-VIS pump-probe experiments and detect upconverted infrared light. Finally, I will show how the hybridization of photons with collective excitations in different material platforms makes light an intrinsic building block of materials [5]. From microscopic modelling we expect light-matter coupling to change material properties, leading to phase transitions and affecting the mechanical response, which opens prospects for future experiments. (a) Detecting collective infrared vibrations in molecular monolayers with surface-enhanced Raman spectroscopy (SERS). (b) Plasmon-polaritons in layered nanoparticle films to combine infrared and visible vibrational spectroscopy. (c) Hybridization of collective excitations with photons in different material platforms.

[1] N.S. Mueller, R. Arul, L.A. Jakob, M. Blunt, T. Foldes, E. Rosta, J.J. Baumberg, Nano Letters 22, 7254–7260 (2022).
[2] R. Arul, D.-B. Grys, R. Chikkaraddy, N.S. Mueller, A. Xomalis, E. Miele, T.G. Euser, J.J. Baumberg, Light: Science & Applications 11, 281 (2022).
[3] N.S. Mueller, E. Pfitzner, Y. Okamura, G. Gordeev, P. Kusch, H. Lange, J. Heberle, F. Schulz, S. Reich, ACS Nano 15, 5523-5533 (2021).
[4] N.S. Mueller, Y. Okamura, B.G.M. Vieira, S. Juergensen, H. Lange, E.B. Barros, F. Schulz, S. Reich, Nature 583, 780-784 (2020).
[5] N.S. Mueller, E.B. Barros, S. Reich, submitted (2022).