Two-Photon Detachment of Inner-Shell Electrons fromLi−

Abstract

We investigate two-photon detachment of an inner 1s electron from the 1s22s2 ground state of Li- using R-matrix Floquet theory. This detachment rate shows a noticeable structure due to shape resonances just above the lowest three doubly excited thresholds of Li. Two-photon detachment of one 1s electron is about twice as likely as two-photon detachment of (at least) one 2s electron. Two-photon detachment of one 1s electron may be observable experimentally through the detection of electrons with kinetic energies between 45 and 65 eV.

Multiphoton inner-shell ionization of the carbon atom

“…In the present photon energy range, emission of a 1s electron requires absorption of (at least) two photons, whereas the emission of a 2s or 2p electron requires absorption of a single photon only. This comparison is similar to a previous comparison of two-photon emission of the 1s electron versus one-and two-photon emission of the outer 2s electron using the R-matrix Floquet approach for Li − [12] or the 1s2s 1 S state in He [13]. To study the response of the carbon atom, we use the recently developed R matrix with time dependence (RMT) approach [14][15][16].…”

Liouville-spaceR-matrix-Floquet description of atomic radiative processes involving autoionizing states in the presence of intense electromagnetic fields

“…by, e. g., Feng and van der Hart (2003), van der Hart (2005van der Hart ( , 2006, and van der . The R-matrix-Floquet method has also been applied to laser-assisted electronatom collision processes, e. g., the n-photon process:…”

“…The € "dressed" atomic states thereby obtained can then be used for the systematic investigation of an extensive class of atomic collision and radiation processes in the presence of intense, stationary (continuous-wave) electromagnetic fields. For a description of atomic processes in ultrashort-pulse electromagnetic fields, an alternative time-dependent R-matrix method has been developed (Burke and Burke 1997, van der Hart et al 2007, Lysaght et al 2008, and Guan et al 2007, 2008. A comprehensive discussion of the R-matrix-Floquet and the time-dependent R-matrix methods has been presented in a recent book by Burke (2011).…”

“…For detailed applications to electromagnetically induced transparency and related pump-probe optical phenomena, we will be especially interested in atomic processes in the presence of both an intense (possibly multiple-mode) electromagnetic field, which is to be treated classically, and a weak multiple-mode electromagnetic field, which may be treated either as a classical field or as a quantum field. In a future investigation, we will introduce a different Liouville-space (reduceddensity-operator) formulation based on the alternative time-dependent R-matrix method (van der Hart 2008, Burke 2011, which is expected to be more appropriate for the description of atomic and molecular processes in the presence of ultrashort-pulse electromagnetic fields for which the Floquet-Fourier expansion would involve a very large set of electromagnetic-field modes.…”

Potential-barrier effects in three-photon-ionization processes

“…[19][20][21]), but it remains to be determined to what extent that understanding applies to nonlinear processes such as multiphoton ionization. For atoms larger than He, a number of theoretical treatments of few-photon ionization processes including electron correlation effects have been carried out [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], primarily for valence-shell electrons and for photon energies in the UV regime. However, in the EUV and x-ray regimes, multiphoton ionization of innershell electrons becomes possible and the number of allowed ionization channels becomes so large as to make ab initio treatment of all electron correlation effects difficult.…”