Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
Informal Seminar
Host: Melanie Müller

Wednesday, January 31, 2024, 2:00 pm
All are invited to meet around 1:40 pm for a chat with coffee & cookies.
PC Seminar Room, G 2.06, Faradayweg 4
Murat Sivis
Max Planck Institute for Multidisciplinary Sciences & University of Göttingen, Germany
Mapping and Controlling of Optical Near Fields in an Ultrafast Transmission Electron Microscope
Electron microscopy facilitates the characterization of optical properties in metallic and dielectric nanostructures through techniques like cathodoluminescence [1] and electron-energy-loss spectroscopy (EELS) [2]. Recently, a novel method called photon-induced near-field electron microscopy (PINEM) [3] has been established in ultrafast transmission electron microscopes, enabling the precise measurement of near-field strengths [4]. In this innovative approach, ultrashort laser pulses (ranging from picoseconds to femtoseconds in duration) excite specific spectral modes of a sample. High-energy electron pulses interacting with the associated near-fields undergo stimulated energy gain and loss. Unlike EELS, which investigates intrinsic properties with a spectral resolution limited by the electron microscope used (sub-100 meV with a monochromator), PINEM allows access to extrinsic optical modes with a spectral resolution limited only by the laser's spectral bandwidth. This is achieved through electron-energy gain spectroscopy (EEGS), where near-field strengths are measured for various laser wavelengths [5]. PINEM and EEGS serve as potent tools in the electron microscopy arsenal.
In this presentation, I will provide an overview of our endeavors in the Göttingen UTEM project [6], focusing on leveraging the capabilities of ultrafast transmission electron microscopy for mapping and controlling optical near-fields in metallic and dielectric nano- and microstructures [7,8]. I will discuss recent studies involving mode-selective reconstruction of plasmonic near fields [9], precise measurements of the time evolution of these near-fields with attosecond accuracy [10], and elaborate on our plans to utilize these near fields for atomic gas excitation and probing nonlinear optical excitations.
1.     E.J.R. Vesseur et al. Nano Lett. 7, 9, 2843–2846 (2007).
2.     J. Nelayah et al. Nature Phys 3, 348–353 (2007).
3.     B. Barwick et al., Nature 462, 902 (2009).
4.     A. Feist et al., Nature 521, 200 (2015).
5.     J.W. Henke et al. Nature 600, 653–658 (2021).
6.     A. Feist et al., Ultramicroscopy 176, 63 (2017).
7.     M. Liebtrau et al. Light Sci Appl 10, 82 (2021).
8.     O. Kfir et al. Nature 582, 46–49 (2020).
9.     H. Lourenço-Martins et al. in preparation (2023).
10.  J.H. Gaida et al. accepted in Nature Photon arXiv:2305.03005 (2023.)