Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy Page: 3 of 24
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
salt/water interactions. SPFM observations of Br-doped NaCl have shown that Br-rich islands segregate
to the surface after exposure to RH above 40% followed by drying, indicating the preferential solvation
and segregation of Br ions.28 In a recently published paper we used SPFM to show that on thin salt
crystallites on SiO2, the contact potential becomes negative for Br and Cl, but not for F upon adsorption
of water and after deliquescence.29 This phenomenon, interpreted as indication of the preferential anion
segregation to the solution-air interface, is studied by spectroscopic means in this work.
We use ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), which provides
photoelectron spectra in the presence of water vapor up to several Torr.3 Using this technique Ghosal
et al.32 have reported the enhancement of halide anions at the surface of saturated solutions of KBr and
KI. More recently they have presented measurements of the ion distribution in mixed NaBr/NaCl
aqueous solutions, showing the segregation of Br to the solution surface. Here we use the same
technique to study the concentration of Br at the surface of ~2.0 nm thick aqueous KBr solution films
on SiO2 films.
Experimental Section
Sample preparation. We used boron-doped p-type Si(100) wafers with a resistivity in the 0.02-0.05
Q-cm range. The cleaning procedure was as follows: First the Si wafer samples were dipped into a
solution of H2SO4 (95 - 97 wt%) : H202 (35 wt%)=3:1 (by volume) for 10 min to remove organic and
metallic contamination. After rinsing with Millipore water for 1 min, they were dipped into a diluted HF
solution (1 - 5 %) for 5 min to remove native oxide layers.34 A clean oxide layer was formed by an
ultraviolet ozone (UV/ozone) generator for 20 min. After the UV/ozone treatment, the sample was
immediately transferred to our AP-XPS chamber.
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Arima, Kenta; Jiang, Peng; Deng, Xingyi; Bluhm, Henrik & Salmeron, Miquel. Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy, article, March 31, 2010; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc830438/m1/3/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.