Photoelectron Spectroscopy using high repetition rate attosecond pulses

University essay from Lunds universitet/Atomfysik; Lunds universitet/Fysiska institutionen

Author: Lisa Rämisch; [2017]

Keywords: Physics and Astronomy;

Abstract: In attosecond physics, pump-probe experiments have been a promising tool to study the fundamental light-matter interaction process of photoionization. In this context, photoelectron spectroscopy is used to spatially and temporally characterize the ejected photoelecron. Low repetition rates can be limited in resolution by space-charge effects \cite{spacecharge} and measurement statistics which can be reduced by high repetition rate measurement of photoelectron spectra. This thesis presents how a high speed digital signal processing card is implemented together with a programmed application software to measure high repetition rate photoelectron spectroscopy. In order to analyze the acquisition conditions and the spectrum generation, the card is tested with a $1kHz$ laser system. We measure the travel time (time-of-flight) of photoelectrons from the moment of ionization until the moment of detection and further convert this quantity to kinetic energy. The results show that both time-of-flight and kinetic energy photoelectron spectra can be measured with the established setup. We corrected a trigger offset to better resolve sidebands created during the pump-probe experiments. We understood that the peak detection function provided by the graphical programming software Labview requires specific input parameters to better resolve the photoelectron time-of-flights and that the current duty cycle needs to be adjusted for high repetition rate measurements. The implementation of the acquisition cards Zero-Suppress mode remains an important feature to reduce the amount of data flow.

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