Extreme Ultraviolet Time-Resolved Photoelectron Spectrometer with an Ultrathin Liquid Flat Jet

Fuente: arXiv
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Main Authors: Koga, Masafumi, Kang, Do Hyung, Heim, Zachary N., Haldar, Neal, Neumark, Daniel M.
Format: Preprint
Published: 2025
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author Koga, Masafumi
Kang, Do Hyung
Heim, Zachary N.
Haldar, Neal
Neumark, Daniel M.
author_facet Koga, Masafumi
Kang, Do Hyung
Heim, Zachary N.
Haldar, Neal
Neumark, Daniel M.
contents A setup for extreme-ultraviolet time-resolved photoelectron spectroscopy (XUV-TRPES) of liquids is described based on a gas-dynamic flat jet formed by a microfluidic chip device. In comparison to a cylindrical jet that has a typical diameter of 10-30 micrometers, the larger surface area of the flat jet with a width of ca. 300 micrometers allows for full overlap of the target with the pump and probe light beams. This results in an enhancement of photoelectrons emitted from the liquid, while simultaneously allowing smaller sample consumption compared with other flat jet techniques utilizing liquid collisions or converging slits. Femtosecond pulses of XUV light at a photon energy of 21.7 eV are prepared by high harmonic generation and a multilayer mirror that selects a single harmonic; the He gas used to form the gas-dynamic flat jet is transparent at this energy. Compared to a cylindrical jet, the photoelectron signal from the liquid is enhanced relative to that from the surrounding vapor jacket. Pump-probe spectra for aqueous thymine show notably higher signals for the flat vs cylindrical jet. Moreover, the time-dependent space-charge shift in UV pump/XUV probe experiments is smaller for the gas dynamic flat jet than for a cylindrical jet with the same flow rate, an effect that is accentuated at higher He backing pressures that yield a thinner jet. This reflects reduced multiphoton ionization of the solute by the UV pump pulse, the primary cause of the space charge shift, as the jet becomes thinner and reaches the thickness of a few tens of nm.
format Preprint
id arxiv_https___arxiv_org_abs_2503_16840
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Extreme Ultraviolet Time-Resolved Photoelectron Spectrometer with an Ultrathin Liquid Flat Jet
Koga, Masafumi
Kang, Do Hyung
Heim, Zachary N.
Haldar, Neal
Neumark, Daniel M.
Chemical Physics
Instrumentation and Detectors
A setup for extreme-ultraviolet time-resolved photoelectron spectroscopy (XUV-TRPES) of liquids is described based on a gas-dynamic flat jet formed by a microfluidic chip device. In comparison to a cylindrical jet that has a typical diameter of 10-30 micrometers, the larger surface area of the flat jet with a width of ca. 300 micrometers allows for full overlap of the target with the pump and probe light beams. This results in an enhancement of photoelectrons emitted from the liquid, while simultaneously allowing smaller sample consumption compared with other flat jet techniques utilizing liquid collisions or converging slits. Femtosecond pulses of XUV light at a photon energy of 21.7 eV are prepared by high harmonic generation and a multilayer mirror that selects a single harmonic; the He gas used to form the gas-dynamic flat jet is transparent at this energy. Compared to a cylindrical jet, the photoelectron signal from the liquid is enhanced relative to that from the surrounding vapor jacket. Pump-probe spectra for aqueous thymine show notably higher signals for the flat vs cylindrical jet. Moreover, the time-dependent space-charge shift in UV pump/XUV probe experiments is smaller for the gas dynamic flat jet than for a cylindrical jet with the same flow rate, an effect that is accentuated at higher He backing pressures that yield a thinner jet. This reflects reduced multiphoton ionization of the solute by the UV pump pulse, the primary cause of the space charge shift, as the jet becomes thinner and reaches the thickness of a few tens of nm.
title Extreme Ultraviolet Time-Resolved Photoelectron Spectrometer with an Ultrathin Liquid Flat Jet
topic Chemical Physics
Instrumentation and Detectors
url https://arxiv.org/abs/2503.16840