Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPhotoionization of Xe 3d electrons in molecule Xe@C60: interplay of intra-doublet and confinement resonances
252
0
0.0
(
0
)
Authors
M. Ya. Amusia
Ask ChatGPT about the research
No Arabic abstract
We demonstrate rather interesting manifestations of co-existence of resonance features in characteristics of the photoionization of 3d-electrons in Xe@C60. It is shown that the reflection of photoelectrons produced by the 3d Xe photoionization affects greatly partial photoionization cross-sections of and levels and respective angular anisotropy parameters, both dipole and non-dipole adding to all of them additional maximums and minimums. The calculations are performed treating the 3/2 and 5/2 electrons as electrons of different kinds with their spins up and down. The effect of C60 shell is accounted for in the frame of the orange skin potential model.
rate research
Read More
Possible reasons that confinement resonances are not observed in a recent photoionization experiment on the endohedral fullerene Ce@C82+ are explored. The effect of the polarization of the fullerene shell in response to the ionization of the endohedrally encaged atom A@Cn, termed the shielding effect, has been investigated and found to be relatively small; no more than a 20% effect near threshold, and much less at higher energies. It is argued that most likely, the absence of confinement resonances in Ce@C82+ is due primarily to the finite thickness of the carbon cage; the off-the-center position and thermal vibration of the encaged atom, discussed elsewhere, further weaken the resonances rendering them beyond the sensitivity of the experiment to detect, in this case. For other situations/endohedrals, the confinement resonances should well be observable, and Ne@C60 is suggested as an excellent candidate.
We discuss the complicated resonance structure of the endohedral atom photoionization cross section. Very strong enhancement and interference patterns in the photoionization cross-section of the valent and subvalent subshells of noble gas endohedral atoms A@C60 are demonstrated. It is shown also that the atomic Giant resonance can be either completely destroyed or remains almost untouched depending on the velocity of photoelectrons that are emitted in the resonances decay process. These effects are results of dynamic modification of the incoming beam of radiation due to polarization of the fullerenes electron shell and reflection of photoelectrons be the fullerenes shell static potential. We have considered the outer np- and subvalent ns-subshells for Ne, Ar, Kr and Xe noble gas atoms. The modification of the Giant resonances is considered for a whole sequence of endohedrals with atoms and ions Xe, Ba, La, Ce+, Ce+4, Eu. The polarization of the fullerene shell is expressed via the total photoabsorption cross section. The photoelectron reflection from the static potential is taken into account in the frame of the so-called bubble potential that is a spherical -type potential.
The photoionization of xenon atoms in the 70-100 eV range reveals several fascinating physical phenomena such as a giant resonance induced by the dynamic rearrangement of the electron cloud after photon absorption, an anomalous branching ratio between intermediate Xe$^+$ states separated by the spin-orbit interaction and multiple Auger decay processes. These phenomena have been studied in the past, using in particular synchrotron radiation, but without access to real-time dynamics. Here, we study the dynamics of Xe 4d photoionization on its natural time scale combining attosecond interferometry and coincidence spectroscopy. A time-frequency analysis of the involved transitions allows us to identify two interfering ionization mechanisms: the broad giant dipole resonance with a fast decay time less than 50 as and a narrow resonance at threshold induced by spin-flip transitions, with much longer decay times of several hundred as. Our results provide new insight into the complex electron-spin dynamics of photo-induced phenomena.
Photoionization cross section $sigma_{nkappa}$, asymmetry parameter $beta_{nkappa}$, and polarization parameters $xi_{nkappa}$, $eta_{nkappa}$, $zeta_{nkappa}$ of Xe and Rn are calculated in the fully relativistic formalism. To deal with the relativistic and correlation effects, we adopt the relativistic random-phase theory with channel couplings among different subshells. Energy ranges for giant emph{d}-resonance regions are especially considered.
In this work, we apply the Monte Carlo wave packet method to study the ultrafast nuclear dynamics following inner-shell photoionization of N2 exposed to an ultrashort intense X-ray pulse. The photon energy of the X-ray pulse is large enough to remove a 1s electron from the N atom in N2. The intermediate state in N+2 is highly excited so that autoionization takes place from this state to the dissociative or non-dissociative electronic states of ungerade and gerade symmetries in N++2. The possible vibrational resonances allowed by the non-dissociative states prevents a direct extraction of the nuclear kinetic release (KER) spectrum from the nuclear wave packets in N++2. Therefore, we propose a hybrid technique by combining the advantages of two energy analysis strategies to obtain the final nuclear KER spectrum of the process. A femtosecond IR probe pulse, which couples the electronic states in N++2 together, is applied to achieve a time-resolved imaging and controlling of the ultrafast dynamics that takes place during double ionization of N2. The influence of the laser parameters including the peak intensity, pulse duration and pump-probe delay, on the nuclear dynamics is also investigated.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
