High-resolution multi-mode electron and ion imaging spectrometer at SXFEL

Abstract

A new multi-mode electron and ion (MEI) imaging spectrometer with two arms of VMI and COLTRIMS/VMI (velocity map imaging/cold-target recoil-ion momentum spectroscopy) is designed to combine various photoelectron and ion detection modes for experiments at Shanghai soft x-ray free-electron laser (SXFEL) facility. The experiments can be optionally operated either with both ion and electron detection in a coincidence/covariance manner (VMI arm and COLTRIMS/VMI arm), or only photoelectron/photoion is detected with the high-resolution VMI arm. The simulated resolutions for 30–150 eV photoelectrons and 3.3 eV–18.0 eV N+ and N2+ photoions are up to 1.0% and 3.1%–1.0% according to our simulation, respectively. MEI spectrometer is expected to improve the experimental abilities significantly considering the low-repetition rate of the SXFEL and to enable the investigation of a diverse range of atomic and molecular phenomena triggered by soft x-ray free electron laser irradiation.