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Title: A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces

Abstract

We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50...150 {micro}m is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100...1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a {chi} = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Chemical Sciences Division
OSTI Identifier:
937449
Report Number(s):
LBNL-998E
Journal ID: ISSN 1463-9076; TRN: US200819%%135
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Physical Chemistry Chemical Physics
Additional Journal Information:
Journal Volume: 10; Journal Issue: 21; Journal ID: ISSN 1463-9076
Country of Publication:
United States
Language:
English
Subject:
54; AEROSOL GENERATORS; APERTURES; AQUEOUS SOLUTIONS; CHEMISTRY; ELECTRONS; ELECTROSTATICS; GASES; KINETICS; METHANOL; ORIFICES; PHOTOEMISSION; SPECTROMETERS; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Starr, David E, Wong, Ed K, Worsnop, Douglas R, Wilson, Kevin R, and Bluhm, Hendrik. A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces. United States: N. p., 2008. Web. doi:10.1039/b800717a.
Starr, David E, Wong, Ed K, Worsnop, Douglas R, Wilson, Kevin R, & Bluhm, Hendrik. A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces. United States. https://doi.org/10.1039/b800717a
Starr, David E, Wong, Ed K, Worsnop, Douglas R, Wilson, Kevin R, and Bluhm, Hendrik. Thu . "A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces". United States. https://doi.org/10.1039/b800717a. https://www.osti.gov/servlets/purl/937449.
@article{osti_937449,
title = {A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces},
author = {Starr, David E and Wong, Ed K and Worsnop, Douglas R and Wilson, Kevin R and Bluhm, Hendrik},
abstractNote = {We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50...150 {micro}m is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100...1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a {chi} = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.},
doi = {10.1039/b800717a},
url = {https://www.osti.gov/biblio/937449}, journal = {Physical Chemistry Chemical Physics},
issn = {1463-9076},
number = 21,
volume = 10,
place = {United States},
year = {2008},
month = {5}
}