Time-resolved resonant photoionization of He using a time-dependent Feshbach method with ultrashort laser pulses

Abstract

We study the photoionization and autoionization of Helium atom subject to ultrashort laser pulses by using a Feshbach formalism in the time domain. We solve the time-dependent Schrödinger equation in terms of a configuration interaction (CI) spectral method, in which the total wavefunction is expanded with configurations defined within bound-like ($\mathcal{Q}$) and scattering-like ($\mathcal{P}$) halfspaces. The method allowsone to provide accurate descriptions of both the atomic structure (energy positions and widths) and the photodynamics. We illustrate our approach by i) calculating the time-resolved one-photon ionization below the He${}^{+}$ ($n$=2) ionization threshold, from $1^1{S}^e$ and $2^1{P}^o$ initial states, then reaching the lowest autoionizing states of ${}^1{S}^e$, ${}^1{P}^o$ and ${}^1{D}^e$ final symmetries ii) studing the temporal formation of the Fano profile of ${}^1{P}^o$ resonances and iii) showing its performance in obtaining the perturbative long-time limit of one- and two-photon ionization cross sections using ultrashort laser pulses following a recently developed procedure in Phys. Rev. A, {\bf 77}, 032716 (2008).

20 pages, 8 figures. Submitted to: J. Phys. B: At. Mol. Opt. Phys

References in corpus (4)

• Cross sections for short pulse single and double ionization of helium
• Theory of ultrafast autoionization dynamics of Fano resonances
• Photoabsorption of attosecond XUV light pulses by two strongly laser-coupled autoionizing states
• Laser-assisted-autoionization dynamics of helium resonances with single attosecond pulses