XPS Chamber

The current project in this chamber focuses on the formation of IrO2(110), a highly reactive late transition metal oxide, grown on the rutile phases of RuO2(110) and TiO2(110). A conformal s-IrO2(110) film has been found to be challenging to make under typical ultra-high vacuum (UHV) conditions, requiring the use of an external high pressure cell for the growth of the film prior to experimentation in UHV. It was discovered by Over et. at. that a conformal rutile IrO2(110) oxide can be created in UHV when grown on a RuO2(110) substrate.

We aim to study the growth of the IrO2(110) layer on the RuO2(110) and TiO2(110) films in a hope to gain insight into the reactivity of IrO2(110) as a function of film thickness. In addition, we hope to control the selectivity of alkane oxidation on IrO2(110) with the use of mixed oxide chemistry of the two films.

Our UHV chamber is equipped with a mass spectrometer, low energy electron spectroscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy in order to characterize the surface of the catalyst as well as the reactivity of the films. The oxides are prepared with the use of atomic oxygen, the source of which is a columated beam of oxygen atoms that are formed via a plasma source. The initial film is prepared on the Ru(0001) surface. Ir atoms are then deposited on the RuO2(110) film via vapor deposition. The film is then again oxidized to create the IrO2(110) film.

In addition, we plan to perform near ambient pressure x-ray photoelectron spectroscopy (APXPS) experiments at an external synchrotron facility in order to collect high resolution XPS data which can be used to determine the oxidation state of adsorbates as well as reaction species.