Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 67: Focus Session: Unoccupied States by Inverse Photoemission II
O 67.9: Talk
Wednesday, March 11, 2026, 17:15–17:30, WILL/A317
Sub-100 meV low-energy inverse photoelectron spectroscopy using an electrostatic monochromator — •Tomoko Onishi1, Taichi Suruga1, Daichi Honma1, Masaya Kai1, Issei Ishimori1, François C. Bocquet2, F. Stefan Tautz2, Harald Ibach2, and Hiroyuki Yoshida1 — 1Chiba University, Chiba, Japan — 2Forschungszentrum Jülich, Jülich, Germany
Inverse photoelectron spectroscopy (IPES) is the optimal experimental method for probing unoccupied electronic states but its applicability has been limited by modest energy resolution. This resolution is determined by the convolution of the electron energy spread and photon-detector bandwidth. The best reported resolution to date is 165 meV, limited by the photon detector [1]. Low-energy IPES (LEIPS) [2], using an optical bandpass filter, achieves a photon-detection resolution of 38 meV. However, the total resolution remains limited to 250 meV due to electron-beam thermal broadening [3]. In this work, we report a LEIPS system with an electron source consisting of a LaB6 cathode, electrostatic monochromator, and deceleration lens system. This design is based on high resolution electron energy loss spectroscopy (HREELS). We modified it to deliver several hundred nA with a capability of energy scan for LEIPS [4]. An electron energy spread of 90 meV is obtained, resulting in a total LEIPS energy resolution of 98 meV. [1] M. Budke et al., Rev. Sci. Instrum. 78, 083903 (2007). [2] H. Yoshida, Chem. Phys. Lett. 539*540, 180 (2012). [3] H. Yoshida, J. Electron Spectrosc. Relat. Phenom. 204, 116 (2015). [4] H. Ibach et al., Rev. Sci. Instrum. 94, 043908 (2023).
Keywords: Inverse photoemission spectroscopy; low-energy inverse photoelectron spectroscopy; energy resolution; electron source; organic materials