1. Fraunhofer IWM,
MicroTribology Center μTC, Wöhlerstrasse
11, 79108 Freiburg, Germany
2. ExxonMobil Research
and Engineering Company, Annandale, New Jersey 08801, United States
3. University of Freiburg, Physics Department, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany