Simulation of photodesorption at the Photon Factory

A model of photodesorption which takes place in the electron storage ring and experimental apparatus in a photon beam line is presented. The model is constructed, based on the kinetics of adsorption, thermal desorption, photodesorption and the evacuation of gas phase molecules, taking account of the energy distribution of adsorption sites and the photon ¯ux distribution on the chamber wall. The calculated results are compared with the experimental photodesorption yield obtained at the Photon Factory. The calculated decay curve of the photodesorption yield against the photon dose agrees well with the experimental ones. # 2001 Elsevier Science B.V. All rights reserved