X-ray Photoelectron Spectroscopy

The X-ray photoelectron spectroscopy facility in the chemistry department houses a high sensitivity Kratos AXIS 165 spectrometer. This state-of-the-art instrument is a high performance spectrometer with imaging capabilities and is designed to meet the demanding needs of surface scientists.


Technique of X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy is a widely used method of determining the chemical composition of a surface. The analysis is done by irradiating a sample with soft x-rays to ionize atoms and releasing core-level photoelectrons. The kinetic energy of the escaping photoelectrons limits the depth from which it can emerge, giving XPS its high surface sensitivity and sampling depth of a few nanometers. Photoelectrons are collected and analyzed by the instrument to produce a spectrum of emission intensity versus electron binding energy. Since each element has a unique set of binding energies, XPS can be used to identify the elements on the surface. Also, peak areas at nominal binding energies can be used to quantify concentration of the elements. Small shifts in these binding energies (chemical shifts) provide powerful information about sample chemical states and short-range chemistry. XPS is suitable for the analysis of both conductors and insulators.

This facility has been supported by the National Science Foundation and the Materials Research Science and Engineering Center (MRSEC) since 2003 and is available for collaborative research projects.


Photo of X-ray photoelectron spectroscopy machine

Key features of the instrument are:

  • 165 mm radius hemispherical analyzer and eight channeltron detection system for excellent energy resolution and sensitivity for small areas
  • Magnetic immersion lens for superior sensitivity for small area analysis and imaging
  • Charge neutralization system for insulating samples
  • Variable temperature sample stage (150-750 K) for temperature controlled measurements
  • Capable of XPS imaging and multipoint spectroscopy
  • Depth profiling with argon ion bombardment
  • Automated sample stage and XYZ manipulator for angle resolved measurements
  • Two x-ray sources: Monochromatic Al and Dual anode (Mg/Al)
  • Fully computer controlled system with windows based Vision software.

XPS Analysis Requests

Internal XPS Analysis Request Form (fillable pdf form)

XPS Request Form – External

Sample Requirements

XPS Rates


For general questions about XPS, the capabilities of the facility and sample analysis strategies or to schedule an appointment contact:

Dr. Karen Gaskell
Chemistry Building, Room B0505
University of Maryland
Department of Chemistry and Biochemistry
College Park, MD 20742
Phone 301.405.4999
Fax 301.314.2600