2010 R&D 100 Winner
All photoelectron spectroscopy systems identify elements by detecting their unique spectral signals. But in typical x-ray photoelectron spectrometry, the signal strength at ambient pressure is too weak to be useful, which means this type of analysis is rarely done on a sample at the same pressure and humidity as that experienced in the natural environment of the object under study.
The APPELS: Differentially Pumped Ambient Pressure PhotoElectron Lens System for Photoemission Studies brings that possibility into the laboratory. Developed by Lawrence Berkeley National Laboratory, Berkeley, Calif., SPECS GmbH, and the Fritz Haber Institute, both of Berlin, Germany, APPELS features an electrostatic lens in each pumping stage that guides electrons through the next aperture with negligible loss, just as an optical lens gathers and focuses visible light. This allows XPS systems to surpass the critical 4.6-torr lower limit of liquid water vapor pressure at 0°C, and reach ambient pressures of over 10 torr. APPELS accomplishes spectrometry at pressures eight orders of magnitude higher than possible in conventional systems, and has already led to breakthroughs in climate change, atmospheric science, nanotechnology, and industrial processes such as heterogeneous catalysis.
Lens system for photoelectron spectroscopy
|(l-r): Miquel Salmeron, D. Frank Ogletree, Hendrik Bluhm, and Zahid Hussain, Lawrence Berkeley National Laboratory|
|Oliver Schaff, SPECS GmbH|
|Sven Maehl, SPECS GmbH|
|Robert Schlögl, Fritz Haber Institute of the Max Planck Society|
The APPELS: Differentially Pumped Ambient Pressure PhotoElectron Lens System for Photoemission Studies Development Team:
Hendrik Bluhm, Lawrence Berkeley National Laboratory
Zahid Hussain, Lawrence Berkeley National Laboratory
D. Frank Ogletree, Lawrence Berkeley National Laboratory
Miquel Salmeron, Lawrence Berkeley National Laboratory
Oliver Schaff, SPECS GmbH
Sven Maehl, SPECS GmbH
Robert Schlogl, Fritz Haber Institute of the Max Planck Society