[4] Petek has developed coherent photoelectron spectroscopy[5][6] and microscopy[7] as methods for studying the dephasing and spatial propagation of polarization fields in solid state materials and nanostructure.
[8] Together with Taketoshi Minato, Yousoo Kim, Maki Kawai, Jin Zhao Archived 2019-07-16 at the Wayback Machine, Jinlong Yang and Jianguo Hou, Petek discovered a delocalized electronic structure created by oxygen vacancy on titanium dioxide surface.
[9] Together with Jin Zhao Archived 2019-07-16 at the Wayback Machine, Ken Jordan and Ken Onda, Petek also discovered wet electron states, where electrons are partially solvated by water and other protic solvents at molecule vacuum interfaces.
[10] Together with Min Feng and Jin Zhao Archived 2019-07-16 at the Wayback Machine, Petek discovered atom-like superatom states of C60, and similar hollow molecules.
[14] Petek has been (2015-2019) a member of the National Research and Development Agency Committee for the National Institute for Materials Science and is currently a senior scientific advisor to the Institute for Molecular Science in Japan.