Electron energy loss spectra of inner-shell excitations of 2π electrons of argon are measured at an incident electron energy of 2500 eV and scattering angles of 0 β and 4 β . The dipole-forbidden transitions of 2π β1 3/2 4π and 2π β1 3/2 5π 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 2π β1 3/2 ππ and 2π β1 1/2 ππ(π β€ 5) of argon are determined. The present results show that the line widths of the electric quadrupole transitions of 2π β1 3/2 4π[5/2 + 3/2]2 and the electric monopole one of 2π β1 3/2 4π[1/2]0 are less than those of the dipole-allowed transitions.
The generalized oscillator strengths, differential cross sections, as well as the integral cross sections for electron impact excitation of the B (1)Delta, C (1)Pi, and D (1)Sigma(+) states of N(2)O have been determined at an incident electron energy of 2500 eV. A generalized oscillator strength analysis reveals that the B (1)Delta<--X (1)Sigma(+) transition is dominated by the quadrupolar component. From the comparison to the previous experimental results, it is found that the first Born approximation is not satisfied for the C (1)Pi excitation while it is valid for the D (1)Sigma(+) excitation at an incident electron energy of 200 eV. The BE-scaled integral cross section for the B (1)Delta excitation from its threshold to 5000 eV was calculated based on its generalized oscillator strength, and the present integral cross sections for the excitation of the C (1)Pi and D (1)Sigma(+) states are in good agreement with the calculations using the BEf-scaling approach.
The valence-shell excitations of nitrous oxide are studied by fast electron energy loss spectroscopy. From the spectra measured at 2.5 keV and scattering angles of 3.5Β°β8.5Β°, it is found that the asymmetric peak of the transition B1Ξ can be well fitted by Haarhoff-Van der Linde function, while the symmetric peaks of the transitions of C1Ξ and D1Ξ£+ can be well fitted by the Voigt function. The parameters of the peak profiles of B1Ξ, C1Ξ and D1Ξ£+, i.e., their energy level positions and linewidths, are determined. With the aid of these parameters, the overlapping spectra measured at the low-energy electron impact can be deconvolved, which provides the possibility to determine the quantitative differential cross sections. The present results also show that the peak profiles of the transitions of B1Ξ, C1Ξ and D1Ξ£+, are independent of the momentum transfer.
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