Concentration and chemical-state profiles at heterogeneous interfaces with sub-nm accuracy from standing-wave ambient-pressure photoemission.
Heterogeneous processes at solid/gas, liquid/gas and solid/liquid interfaces are ubiquitous in modern devices and technologies but often difficult to study quantitatively. Full characterization requires measuring the depth profiles of chemical composition and state with enhanced sensitivity to narrow interfacial regions of a few to several nm in extent over those originating from the bulk phases on either side of the interface. We show for a model system of NaOH and CsOH in an ~1-nm thick hydrated layer on α-Fe2O3 (haematite) that combining ambient-pressure X-ray photoelectron spectroscopy and standing-wave photoemission spectroscopy provides the spatial arrangement of the bulk and interface chemical species, as well as local potential energy variations, along the direction perpendicular to the interface with sub-nm accuracy. Standing-wave ambient-pressure photoemission spectroscopy is thus a very promising technique for measuring such important interfaces, with relevance to energy research, heterogeneous catalysis, electrochemistry, and atmospheric and environmental science.
1] Department of Physics, University of California Davis, Davis, California 95616, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Slavomír
S
Nemšák
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Andrey
A
Shavorskiy
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Osman
O
Karslioglu
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Ioannis
I
Zegkinoglou
1] Department of Physics, University of California Davis, Davis, California 95616, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Arunothai
A
Rattanachata
1] Department of Physics, University of California Davis, Davis, California 95616, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Catherine S
CS
Conlon
1] Department of Physics, University of California Davis, Davis, California 95616, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Armela
A
Keqi
Department of Physics, University of California Davis, Davis, California 95616, USA.
Peter K
PK
Greene
Department of Physics, University of California Davis, Davis, California 95616, USA.
Edward C
EC
Burks
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Farhad
F
Salmassi
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Eric M
EM
Gullikson
IBM Almaden Research Center, San Jose, California 95120, USA.
See-Hun
SH
Yang
Department of Physics, University of California Davis, Davis, California 95616, USA.
Kai
K
Liu
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Hendrik
H
Bluhm
1] Department of Physics, University of California Davis, Davis, California 95616, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Charles S
CS
Fadley