Inner-Shell Excitations of 2p Electrons of Argon Investigated by Fast Electron Impact with High Resolution

Electron energy loss spectra of inner-shell excitations of 2p electrons of argon are measured at an incident electron energy of 2500eV and scattering angles of 0°and 4°.The dipole-forbidden transitions of 2_(p3/2)^(-1)4p and 2_(p3/2)^(-1)5p are observed in the measured spectra and assigned based on the calculations of the Cowan code.The positions and line widths for the excitations of 2_(p3/2)^(-1)nl and 2_(p1/2)^(-1)nl(n≤5)of argon are determined.The present results show that the line widths of the electric quadrupole transitions of 2_(p3/2)^(-1)4p[5/2+3/2]_(2)and the electric monopole one of 2p_(3/2)^(-1)4p[1/2]0 are less than those of the dipole-allowed transitions.