Strong field detachment of a negative ion with non-zero angular momentum: application to F 

Abstract

We apply our recently developed, model-independent quantum approach for intense laser detachment of a weakly bound electron to interpret a recent experiment on above-threshold detachment (ATD) of the F− ion. We find that the measured electron energies correspond to the ‘Keldysh part’ of the ATD spectrum, just below the onset of our predicted rescattering plateau. Overall, our predicted ATD spectrum (using a scaled peak intensity and focal averaging) is in excellent agreement with the experimental data, except for certain structures observed for electron energies above 12.6 eV that we attribute to known two-electron resonances of F−. A number of analytical approximations to our exact p-state ATD amplitude are obtained, and their accuracy is investigated.

Evidence for Rescattering in Intense, Femtosecond Laser Interactions with a Negative Ion

“…However, our experimental results provide convincing evidence for a direct double detachment process which is consistent with the rescattering mechanism. This lends support to the recent theoretical work which predicts that rescattering will occur if an intact negative ion can be exposed to a sufficiently strong field [12,13,[15][16][17].…”

“…However, comparison of the experimental results with the calculations in Ref. [13] highlighted structure in the electron spectra which could be due to resonant elastic scattering of the electron, which is a common feature in electron-atom collisions [14].…”

“…More recent work, involving a modification of a Keldysh type theory to take into account rescattering [12] and a fully quantum analysis [13], do predict a plateau in the electron spectrum, albeit at energies for which experimental statistics in Ref. [11] were too low.…”

Threshold-related effects on the high energy plateau in above-threshold detachment

“…As CCs affect both the total and partial detachment rates, one expects to observe signatures of CCs in photoelectron angular distributions [24,[34][35][36][37][38][39][40][41]. The sensitivity of two-and three-photon angular distributions to variations of the laser intensity near detachment thresholds have been studied both experimentally [34,37] and theoretically [35,36,41] for H -.…”

“…The sensitivity of two-and three-photon angular distributions to variations of the laser intensity near detachment thresholds have been studied both experimentally [34,37] and theoretically [35,36,41] for H -. The angular distribution of ATD electrons for F - [38][39][40], as well as for other halogen negative ions [40], have been investigated for fixed laser intensity. Only recently [24] have the variations of 8-and 9-photon F -detachment ADs been investigated as a function of laser intensity in the vicinity of CCs.…”