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.
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机译：Dynamical correlation in double excitations of helium studied by high-resolution and angular-resolved fast-electron energy-loss spectroscopy in absolute measurements - art. no. 193203
