Double-Core-Hole States in Neon: Lifetime, Post-Collision Interaction, and Spectral Assignment

Abstract

Using synchrotron radiation and high-resolution electron spectroscopy, we have directly observed and identified specific photoelectrons from K^{-2}V states in neon corresponding to simultaneous 1s ionization and 1s→valence excitation. The natural lifetime broadening of the K^{-2}V states and the relative intensities of different types of shakeup channels have been determined experimentally and compared to ab initio calculations. Moreover, the high-energy Auger spectrum resulting from the decay of Ne^{2+}K^{-2} and Ne^{+}K^{-2}V states as well as from participator Auger decay from Ne^{+}K^{-1}L^{-1}V states, has been measured and assigned in detail utilizing the characteristic differences in lifetime broadenings of these core hole states. Furthermore, post collision interaction broadening of Auger peaks is clearly observed only in the hypersatellite spectrum from K^{-2} states, due to the energy sharing between the two 1s photoelectrons which favors the emission of one slow and one fast electron.

Detailed assignment of normal and resonant Auger spectra of Xe near the L edges

“…Since the Auger spectra are measured at excitation energies below the first satellites in the photoelectron spectrum, these spectral features can be assigned to 5p → 6p shake-up transitions during the Auger decay [17]. These assignments are based on the fact that the kinetic energies of these two lines are approximately 23 eV below those of the main lines at binding energies of 768 and 780 eV, which agrees well with the excitation energies of 22-25 eV for the 5p 6 → 5p 5 6p transition in the Z + 2 atom Ba III [20].…”

“…In particular, in this energy range where the emitted photoelectrons can have very high kinetic energy, we have shown that recoil phenomena due to the momentum of the photoelectron become important [4]. Furthermore, super-shake-up structures related to final states with two vacancies in the core shell(s) and one excited electron can be measured [5][6][7]. In addition, ultrafast nuclear motion on the femtosecond and even subfemtosecond time scale [8] as well as ultrafast dissociation following core excitation and subsequent Auger cascade [9,10] can be observed.…”

Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime

“…The lifetimes of 1s −2 DCH and the corresponding 1s −1 SCH states were previously reported for Ca, V, Cr, Co and Zn atoms [35], where the former were found to be 2.2 times shorter than the latter. In our recent work on 1s −2 DCH states in neon [23] and 2p −2 DCH states in argon [36] we have reported the ratios of 2.9 and 2.8, respectively. In order to validate our method, we have applied it to the previously measured RIXS and RAS in CH 3 Cl excited at the Cl K-shell [9].…”

“…However, the major difference between these techniques appears in the electronic final states reached upon relaxation. In the case of RIXS, the molecule remains neutral with an electron in the excited orbital and a single hole, whereas in the case of resonant spectator Auger decay, the molecule becomes singly charged with an electron in the excited orbital and a double hole.Spectroscopy of double core-hole (DCH) states, created either with intense XFEL radiation through multiphoton absorption [15][16][17] or with high-energy photons provided by synchrotron radiation [18][19][20][21][22][23], has been a hot topic in the recent years. Understanding the nuclear dynamics of DCH states in molecules, formed in the course of cascade relaxations, is of particular interest in relation to the radiation-induced damage in organic tissue and coherent diffraction imaging [24,25].…”

“…(3), where the lifetime of the final state was neglected [9]. As suggested in [23], the Γ DCH /Γ SCH ratio must be dependent on the effective charge of the nucleus seen by electrons as well as on principal quantum number of the shells involved in the relaxation. For atoms with high atomic number and consequently, large effec- tive charge, the ratio is expected to converge to 2.…”