Gas Pulse–X-Ray Probe Ambient Pressure Photoelectron Spectroscopy with Submillisecond Time Resolution

Abstract

A setup capable of conducting gas pulse–X-ray probe ambient pressure photoelectron spectroscopy with high time resolution is presented. The setup makes use of a fast valve that creates gas pulses with an internal pressure in the mbar range and a rising edge of few hundreds of microseconds. A gated detector based on a fast camera is synchronized with the valve operation to measure X-ray photoemission spectra with up to 20 μs time resolution. The setup is characterized in several experiments in which the N2 gas is pulsed either into vacuum or a constant flow of another gas. The observed width of the pulse rising edge is 80 μs, and the maximum internal pulse pressure is ∼1 mbar. The CO oxidation reaction over Pt (111) was used to demonstrate the capability of the setup to correlate the gas phase composition with that of the surface during transient supply of CO gas into an O2 stream. Thus, formation of both chemisorbed and oxide oxygen species was observed prior to CO gas perturbation. Also, the data indicated that both the Langmuir–Hinshelwood and Mars-van-Krevelen mechanisms play an important role in the oxidation of carbon monoxide under ambient conditions.

Spiers Memorial Lecture: prospects for photoelectron spectroscopy

“…Indeed, a demonstration of sub-ms time resolution in gas-pulsing experiments was published in 2021. 70 This utilised gated detection based on a fast camera, combined with short gas pulses generated using a fast valve that generates pulses with a rising edge of a few 100 ms, and internal pressures in the mbar range. 70 The fast camera shutter was triggered by the valve operation.…”

“…70 This utilised gated detection based on a fast camera, combined with short gas pulses generated using a fast valve that generates pulses with a rising edge of a few 100 ms, and internal pressures in the mbar range. 70 The fast camera shutter was triggered by the valve operation. The development of time-resolved NAP-XPS measurements is an exciting area of current development that is discussed further in Section 2.7.…”

Characterization of model and real catalysts by APXPS

“…The hundreds of ms range is already accessible in 3 rd and 4 th generation synchrotrons directly using the fast, snapshot, mode of MCP/CCD or delay line detectors [8,16]. Essential areas and phenomena like chemical kinetics, detection of short-lived surface intermediates, spectators and active phase identification, segregation or nanoparticle restructuration can be tackled.…”

“…Shavorskiy et al have developed a pump and probe scheme that can reach 20 µs resolution, at the Hippie beamline in Max IV [16]. A fast valve is used to create ms gas pulses in the mbar range.…”

Following the Kinetics of Undercover Catalysis with APXPS and the Role of Hydrogen as an Intercalation Promoter

“…Here, we make use of a recently developed methodology for studying fast surface changes during catalytic reactions. 32,33 The method is based on gas pulses of varying compositions that oscillate a catalytically active surface between active and inactive phases. In the case of undercover graphene chemistry, the gas pulses create an artificial driving force for pushing the reactants (oxygen, hydrogen, or CO) under the graphene flakes.…”