Low energy electron transmission through layered materials and chiral organic films

Neu, P.S. (2024)

Doctoral Thesis

In this Ph.D. thesis we study the interaction of low energy electrons with thin materials, namely layered materials (graphene, hexagonal boron nitride, molybdenum disulfide) and organic films. At these low energies the quantum mechanical wavelength of the electron wave function is in the order of a few Angstroms, thus comparable to the interlayer distance in layered materials. This leads to resonances in the electron reflection/transmission spectrum, comparable to the interference of light when it is reflected from a thin film. We use low energy electron microscopy (LEEM) and electron Volt transmission electron microscopy (eV-TEM) to determine the energy dependent electron mean free path (MFP) and identify resonant transmission/reflection states related to the unoccupied band structure. Furthermore, we use photoemission electron microscopy (PEEM) to image low energy electrons from a gold surface covered with a film of chiral organic molecules. We image the photoexcited electrons and compare the intensity of photoemission caused by different (circular) polarizations of light.

• 2D materials
• van der Waals materials
• low energy electron microscopy (LEEM)
• heterostacks
• mean free path (MFP)
• graphene
• hexagonal boron nitride (hBN)
• molybdenum disulfide (MoS2)
• photoemission microscopy (PEEM)
• chiral molecules

• All authors: Neu, P.S.
• Supervisor: Molen, S.J. van der: Tromp, R.M.
• Committee: Kumpf, C.; Zanoli, Z.; Aarts, J.; Exter, M.P. van; Oosterkamp, T.H.; Ruitenbeek, J.M. van
• Qualification: Doctor (dr.)
• Awarding Institution: Leiden Institute of Physics (LION), Faculty of Science, Leiden University
• Date: 2024-06-12
• Sponsorship: NWO