Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMagnetic-field-dependent angular distributions and linear polarizations of emissions from the $2p^53s~^3P_2$ state in Ne-like ions
165
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We studied the effect of an external magnetic field on the angular distributions and the linear polarizations of emissions from the $2s^22p^53s~^3P^o_2$ state in Ne-like ions. Since a B-dependent E1 decay channel is opened by the magnetic field and competes with the inherent M2 transition, the angular distributions and the linear polarizations strongly depend on the magnetic field strength (B). As an example, we illustrated the effect in Ne-like Mg. The B-dependent angular distributions and linear polarization degrees can also be considered as a tool for diagnostics of the magnetic field in plasmas.
rate research
Read More
The hyperfine induced $2s2p ^3P_0, ^3P_2 to 2s^2 ^1S_0$ E1 transition probabilities of Be-like ions were calculated using grasp2K based on multi-configuration Dirac-Fock method and HFST packages. It was found that the hyperfine quenching rates are strongly affected by the interference for low-Z Be-like ions, especially for $2s2p ^3P_0 to 2s^2 ^1S_0$ transition. In particular, the trends of interference effects with atomic number $Z$ in such two transitions are not monotone. The strongest interference effect occurs near Z=7 for $2s2p ^3P_0 to 2s^2 ^1S_0$ E1 transition, and near Z=9 for $2s2p ^3P_2 to 2s^2 ^1S_0$ E1 transition.
The combination of photoelectron spectroscopy and ultrafast light sources is on track to set new standards for detailed interrogation of dynamics and reactivity of molecules. A crucial prerequisite for further progress is the ability to not only detect the electron kinetic energy, as done in traditional photoelectron spectroscopy, but also the photoelectron angular distributions (PADs) in the molecular frame. Here carbonylsulfide (OCS) and benzonitrile molecules, fixed in space by combined laser and electrostatic fields, are ionized with intense, circularly polarized, 30 femtosecond laser pulses. For 1-dimensionally oriented OCS the molecular frame PADs exhibit pronounced anisotropies, perpendicular to the fixed permanent dipole moment, that are absent in PADs from randomly oriented molecules. For 3-dimensionally oriented benzonitrile additional striking structures appear due to suppression of electron emission in nodal planes of the fixed electronic orbitals. Our theoretical analysis, relying on tunneling ionization theory, shows that the PADs reflect nodal planes, permanent dipole moments and polarizabilities of both the neutral molecule and its cation. The calculated results are exponentially sensitive to changes in these molecular properties thereby pointing to exciting opportunities for time-resolved probing of valence electrons dynamics by intense circularly polarized pulses. Molecular frame PADs from oriented molecules will prove important in other contexts notably in emerging free-electron-laser studies where localized inner shell electrons are knocked off by x-ray pulses.
We investigated experimentally and theoretically dielectronic recombination (DR) populating doubly excited configurations $3l3l$ (LMM) in Fe XVII, the strongest channel for soft X-ray line formation in this ubiquitous species. We used two different electron beam ion traps and two complementary measurement schemes for preparing the Fe XVII samples and evaluating their purity, observing negligible contamination effects. This allowed us to diagnose the electron density in both EBITs. We compared our experimental resonant energies and strengths with those of previous independent work at a storage ring as well as those of configuration interaction, multiconfiguration Dirac-Fock calculations, and many-body perturbation theory. This last approach showed outstanding predictive power in the comparison with the combined independent experimental results. From these we also inferred DR rate coefficients, unveiling discrepancies from those compiled in the OPEN-ADAS and AtomDB databases.
We present the results of a detailed theoretical study which meets the spatial and temporal criteria of the Debye-Huckel (DH) approximation on the variation of the transition energies as well as the oscillator strengths for the ${2p^53d ^1P_1rightarrow2p^6 ^1S_0}$ (3C line) and the ${2p^53d ^3D_1rightarrow2p^6 ^1S_0}$ (3D line) transitions of the Ne-like ions subject to external plasma. Our study shows that the redshifts of the transition energy follow the general scaling behaviors similar to the ones for the simple H-like and He-like ions. Whereas the oscillator strength for the 3C line decreases, the oscillator strength for the spin-flipped 3D line increases as the strength of the outside plasma increases. As a result, their ratio is amplified subject to outside plasma environment. We further demonstrate that the plasma-induced variation between the relative strength of the 3C and 3D transitions is mainly due to the spin-dependent interactions which dictate the mixing of the $^1P_1$ component in the $^3D_1$ upper state of the 3D transition. In addition, we are able to find that the ratio between the relative oscillator strengths of the 3C and 3D lines in the presence of the plasma to their respective plasma-free values varies as a nearly universal function of $[(Z-9.2)DZ]^{-1.8}$, with $Z$ the nuclear charge and $D$ the Debye length. The results of this study should be of great help in the modeling and diagnostic of astrophysical plasmas as well as laboratory plasmas.
We investigate the possibility of observing a magneto-transverse scattering of photons from alkaline-earth-like atoms as well as alkali-like ions and provide orders of magnitude. The transverse magneto-scattering is physically induced by the interference between two possible quantum transitions of an outer electron in a S-state, one dispersive electric-dipole transition to a P-orbital state and a second resonant electric-quadrupole transition to a P-orbital state. In contrast with previous mechanisms proposed for such an atomic photonic Hall effect, no real photons are scattered by the electric-dipole allowed transition, which increases the ratio of Hall current to background photons significantly. The main experimental challenge is to overcome the small detection threshold, with only 10^{-5} photons scattered per atom per second.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
