The first level plasmons of Si in pure Si state

SiO2 state and Si3N4 state (corresponding to bonding energy of 116.95

122.0 and 127.0 eV respectively) were investigated directly with X-ray Photoelectron Spectroscopy (XPS) before and after Co irradiation. The experimental results demonstrate that there exist two interfaces

one consists of 60 plasmons of Si in Si3N4 state and in SiO2 state

while the other is made of plasmons of Si in pure Si state and in SiO2 state. When the Si3N4/SiO2/Si samples were irradiated by Co

the interface at Si3N4/SiO2 was extended and at the 60 same time the center of this interface moved towards the surface of Si3N4. The concentration of plasmons in SiO2 state was decreased at the SiO2/Si interface

and effects of radiation bias field on plasmons in the SiO2/Si interface were observable. Finally

the mechanism of experimental results is analyzed by the quantum effect of plasmons excited by photoelectrons.