Adsorbed oxygen effect on excited particle emission under ion bombardment of molybdenum surface

Variation in photon emission intensities as a function of the surface coverage by adsorbed oxygen I(THETA) was studied experimentally. The coverage was varied by changing the oxygen pressure P in the vacuum chamber under stationary conditions of bombardment. Dependences I(P) for atomic lines of sputtered and scattered particles, as well as those for continuous radiation bands, have a complex s-shape. It is found that photon emission nonlinearly depends upon coverage even in the low coverage region theta <<1. An assumption was made that the nonlinear dependences I(THETA) are connected with different effects of oxygen atoms, adsorbed in different states of adsorption, on the excitation of secondary particles. Besides, the fundamental change in excitation probability of the secondary particles is caused by their interaction with oxygen atoms in low energy-bond states