(e, eγ)-coincidence studies to determine spin-resolved Stokes parameters of the 185 nm emission line in mercury

Abstract

Direct measurements of the three Stokes parameters (polarization components) P 1 , P 2 and P 3 of the VUV Hg transition 6s6p 1 P 1 → 6s 2 1 S 0 (185 nm) have been carried out at electron impact energies of 15 eV, 50 eV and 100 eV. Within the experimental uncertainty, no influence of the electron spin was discovered for scattering angles θ 30 • . At 15 eV excitation energy and scattering angles θ 80 • , increasing spin effects become apparent. The experimental data are compared to theoretical predictions from a first-order full-relativistic distortedwave model, a five-state Breit-Pauli R-matrix (close-coupling) approach, and a convergent close-coupling model, in which relativistic effects are accounted for by adding non-relativistic amplitudes using known intermediate-coupling coefficients. At scattering angles θ 15 • , all of the theories reproduce the experimental data well, whereas the CCC model exhibits the best overall agreement with experiment at large scattering angles.

Electron-impact excitation of singly charged metal ions

“…In this contribution, we present a systematic study of electronimpact excitation of singly charged metal ions using the RDW theory. In our previous work we have successfully applied the RDW method to electron-impact excitation of various multielectron neutral atoms including inert gases [1,2,23] and provided differential and angle integrated cross sections as well as polarization of photon emission [3,24,25]. The same RDW theory has been extended to the electron-ion excitation, and is applied in the present study for singly charged metal ions.…”

“…In our present calculation, we have taken into account the relativistic Breit interaction in addition to the (usual) projectile electron-target Coulomb interaction, anticipating its contribution might be important for ions. No Breit corrections were included in our earlier RDW calculations for neutral atoms [1,2,[23][24][25][26]. Using the RDW theory, we present here calculations for differential and integrated cross sections for the resonance transitions ns 1/2 -np 1/2 and ns 1/2 -np 3/2 in Mg + (n = 3), Ca + (n = 4), Zn + (n = 4), Cd + (n = 5), and Ba + (n = 6) in the electron-energy range up to 300 eV.…”

Total polarization of the 185 nm emission line of mercury excited by electron impact

“…(1) Here the two linear polarizations P 1,2 and the circular polarization P 3 were defined in [1] for photons emitted perpendicular to the scattering plane. This parameter is an adequate means to determine whether or not the system after the collision is in a pure quantum state [4][5][6].…”

“…The Stokes parameters P 1 , P 2 and P 3 of the VUV Hg transition 6s6p 1 P 1 → 6s 2 1 S 0 (185 nm) have recently been measured in electron-photon (e, eγ ) coincidence studies using spin-polarized incident electrons [1]. The above Stokes parameters describe the polarization of photons emitted perpendicular to the scattering plane.…”

Comparison of experiment and theory for superelastic electron-collision studies from laser-aligned magnesium

“…The electron-photon coincidence technique has been used to study collisions with different atomic targets, both experimentally and theoretically. These include the lighter targets hydrogen [4][5][6], helium [7,8], and magnesium [9,10]; intermediate targets including calcium [11][12][13][14][15][16], neon [17][18][19], and zinc [20][21][22][23]; and heavier targets including cadmium [24][25][26], lead [27], and mercury [28][29][30][31][32][33].…”