Surface chemistry plays a key role in the performance of most advanced, high-technology materials and products.  Surface composition is highly important because the surface constitutes the direct zone of interaction between any solid material and its environment, be it gases, liquids, or other solids.  Therefore, the surface chemistry of a material (eq, oxidation states, ionic and molecular bonding, lateral and depth distribution of elements and compounds) will affect many fundamental material properties such as adhesion strength, biological compatibility, catalytic activity, corrosion resistance, oxidation behavior, surface appearance, tribological performance, and wettability, among others.  X-ray photoelectron spectroscopy (XPS), also known as electron spectroscopy for chemical analysis (ESCA), is the premier qualitative and quantitative analytical technique for characterizing the chemical composition of the topmost surface (≤ ~10 nm) of solid materials.

For the past year, RJLG scientists have been using the state-of-the-art Model K-Alpha XPS instrument manufactured by Thermo Scientific (http://www.thermo.com/).  RJLG is the first commercial analytical testing laboratory in the United States to offer XPS services with the K-Alpha instrument and is one of only a small handful of U.S. laboratories using a K-Alpha XPS.  In fact, RJLG serves as one of Thermo Scientific's demonstration laboratories for potential buyers of the K-Alpha XPS and our surface analysis experts are also assisting Thermo Scientific personnel with developing new applications for the K-Alpha.  A number of exciting joint RJLG-Thermo Scientific XPS presentations are upcoming at major international conferences including: Nanotech Europe 2009 in Berlin, Germany (September 28-30, 2009), the 13^th European Conference on Applications of Surface and Interface Analysis (ECASIA) in Antalya, Turkey (October 18-23, 2009), and the American Vacuum Society (AVS) 56^th International Symposium & Exhibition in San Jose, CA (November 8-13, 2009).

The K-Alpha is the ideal XPS instrument for materials surface characterization.  Materials which can be analyzed by XPS include such diverse substances as biologic samples, catalysts, ceramics, composites, glass, metals, polymers, semiconductors, thin films, and other ultra-high vacuum compatible solids, fibers, and powders.  In addition to analyzing the surface composition of the outer ~10 nm of materials, XPS can also be combined with argon ion beam sputtering to perform destructive compositional depth profiling of coatings and other materials over depths ranging from a few nanometers to several micrometers.  Just recently, Thermo Scientific provided RJLG with an automated K-Alpha tilt-stage for sample handling, which provides what is known as angle-resolved XPS (ARXPS) analysis.  Performing XPS measurements with the sample titled at a grazing angle relative to the electron energy analyzer gives the operator the ability to vary the sampling depth of the analysis with the tilt angle.  Combining ARXPS measurements at multiple angles with advanced K-Alpha data processing software allows unique non-destructive depth profiles to be determined over the top ~1-10 nm of a material surface without the need for ion sputtering.  This technique is most useful for characterizing in-depth variations in the composition of ultra-thin films used in semiconductor devices and other nanomaterials. 

RJLG has been using the K-Alpha XPS to investigate and solve complex client problems including: corrosion of metals; evaluation of surface passivation treatments for stainless steel; characterization of functional coatings and thin films on metals, glass, and other advanced devices; surface characterization of environmental particulate; pharmaceutical-related surface studies; and surface characterization of various engineered nanoparticles, such as activated carbon, carbon black, and carbon nanotubes.  If your products or processes involve surface chemistry, RJLG's K-Alpha XPS and experienced scientific personnel can help solve your most complex surface-related problems.

For more information, please contact RJLG's Brian Strohmeier, Manager of the Surface Analysis Laboratory, at bstrohmeier@rjlg.com.