Excitation-energy dependence of the resonant Auger transitions to the4p4(D1)np

Abstract

The energy dependencies of the intensities and angular distribution parameters ␤ of the resonant Auger final states 4p 4 ͑ 1 D͒np ͑n =5,6͒ of Kr were determined experimentally in the excitation-energy region of the overlapping 3d 3/2 −1 5p and 3d 5/2 −1 6p resonances. The experimental results were compared with the outcome of multiconfiguration Dirac-Fock calculations. Combining experimental and calculated results allowed us to study interference effects between the direct and several resonant channels that populate the 4p 4 ͑ 1 D͒np states. The inclusion of the direct channel was crucial in order to reproduce the observed energy behavior of the angular distribution parameters. It was also important to take into account experimentally observed shake transitions.

Coherent xuv pulse induced resonant Auger process in the krypton atom

“…We have also found that the electrons released from two different core-excited states will interfere in their common continuum and the signatures of such interference can be seen in the computed electron spectrum. This result is in accordance with the lifetime interference effects predicted on exposure of Kr to weak synchrotron radiation [8,9]. However, interestingly we find that small energy separation and comparable partial RA decay rates of the two core-excited states are not sufficient to observe strong interference effects between RA electrons released from two different core-excited states into the common continuum in the electron spectrum.…”

“…Since RA decay is taking place from a coherent superposition of core-excited states and the energy separation between the two states is lower than the bandwidth of the pulse there is a strong possibility that RA electrons released from two different core-excited states can interfere in their common continuum in the manner as predicted for the neon atom in [17]. This type of interference has been predicted for the krypton atom exposed to weak synchrotron radiation and has been termed as lifetime interference [8,9]. To clarify whether any interference is taking place at all we compute the electron spectrum of the superposition of the ) and only…”

“…Over the last few decades the resonant Auger (RA) process has been extensively investigated using synchrotron radiation [1][2][3][4][5][6][7][8][9][10]. Recent availability of free electron lasers (FEL) has created access to high intensity ultrashort x-ray pulses that can set off inner shell processes like that of the RA process, and is providing opportunities for re-investigating the RA process under high intensity x-ray lasers.…”

“…The possibility of simultaneous excitation of multiple core-excited states from the ground state has been explored earlier in [20,21]. This type of interference is also possible under weak laser fields, providing the energy separation between the two core-excited states is substantially small and falls within the bandwidth of the laser pulse; this has been termed as lifetime interference [8,9].…”

“…The objective of our work is to investigate the RA process from a superposition of two close lying core-excited states in the Kr atom. The RA process in the Kr atom has been thoroughly investigated in the weak field regime [1,8,9]. In this work we focus on investigating the RA process in the Kr atom in the strong field regime by considering the exposure of the Kr atom to an intense coherent ultrashort xuv laser.…”