Abstract
Synchrotron radiation from the 2.5 GeV electron synchrotron at the Physikalisch Institut of the University of Bonn has been used to measure the asymmetry parameter for the photoionisation of CH4 as a function of photon energy. Good agreement with existing experimental data is obtained at 21.2 eV. However, the observed slow general increase of beta with photon energy is at variance with published calculated curves. Some structure is observed in the experimental curve and similarities with the 2p photoelectron asymmetry parameter for neon are discussed.