In XPS, a monochromatic x-ray is employed to eject electrons from the atoms in a solid sample. The kinetic energy of the ejected electron is measured by an electrostatic analyzer that focuses the emitted electrons onto a solid state detector. This is achieved in ultrahigh vacuum. Based on the atomic structure of the emitting atom, the binding energies of the emitted electrons are quantized. The exciting x-ray penetrates deeply into the sample and excites photoelectrons throughout the penetration depth. However, electrons emitted from deeply in the solid lose their energy through collisions with the atomic lattice. Therefore, only electrons emitted from the first several atomic layers of the solid arrive at the detector without losing energy. Thus, XPS is truly a surface technique. XPS is sensitive to all elements in the periodic chart with the exception of hydrogen and helium. The core electron binding energies measured undergo chemical shifts as a function of the oxidation state of the emitting atom. Thus the chemical state of atoms present on the surface of the solid can be determined. The intensity of the photoelectron line is proportional to the chemical composition of the surface. Therefore, semi-quantitative analysis of the surface is readily available. Both conducting and insulating samples can be analyzed.
Contamination in the manufacturing process often leads to costly production losses. Identifying the contaminant can help pinpoint the source of the problem and minimize negative effects. Constellation has the tools to effectively analyze and identify many types of contamination.
Incoming material inspection and verification is an important part of quality control in the aerospace, automotive and defense industries. Materials used in manufacturing processes are routinely analyzed for adherence to quality specifications, including SAE-AMS and military specifications (MIL-Spec). With an extensive array of analytical instrumentation and experienced chemists and scientists, Constellation can perform incoming chemical and physical tests on a wide range of materials. The laboratory provides testing using US Pharmacopeia, Reagent Chemical, and ASTM methodologies, as well as procedures developed to meet the customer’s
Manufacturers often encounter unknown materials in their processes. Such materials include an unknown substance discovered in the manufacturing process, a suspect material from a new supplier, or a poorly-performing material. Constellation specializes in the identification of most types of materials, including metals, plastics, minerals and liquids. Most materials can be identified based on chemical composition and physical properties. The material identifications can range from extensive analyses to ensure high-quality materials to positive material identification (PMI) screening methods for rapid comparison of unknown materials to known samples.
Constellation can provide analysis of the first several atomic layers of a solid sample using x-ray photoelectron spectroscopy (XPS) and/or Auger electron spectroscopy (AES). These techniques provide semi-quantitative analysis of the composition of the solid surface. These techniques are the instrumental methods of choice for characterization of such things as surface contamination, chemical imperfections and corrosion. Coupling the techniques with inert ion sputtering provides a semi-quantitative composition of the solid sample as a function of depth.