Resonance-Enhanced Multiphoton Ionization in the X-Ray Regime




LaForge Aaron C., Son Sang-Kil, Mishra Debadarshini, Ilchen Markus, Duncanson Stephen, Eronen Eemeli, Kukk Edwin, Wirok-Stoletow Stanislaw, Kolbasova Daria, Walter Peter, Boll Rebecca, De Fanis Alberto, Meyer Michael, Ovcharenko Yevheniy, Rivas Daniel E., Schmidt Philipp, Usenko Sergey, Santra Robin, Berrah Nora

PublisherAMER PHYSICAL SOC

2021

Physical Review Letters

PHYSICAL REVIEW LETTERS

PHYS REV LETT

ARTN 213202

127

21

7

0031-9007

1079-7114

DOIhttps://doi.org/10.1103/PhysRevLett.127.213202(external)

https://arxiv.org/abs/2110.08145(external)



Here, we report on the nonlinear ionization of argon atoms in the short wavelength regime using ultraintense x rays from the European XFEL. After sequential multiphoton ionization, high charge states are obtained. For photon energies that are insufficient to directly ionize a 1s electron, a different mechanism is required to obtain ionization to Ar17+. We propose this occurs through a two-color process where the second harmonic of the FEL pulse resonantly excites the system via a 1s -> 2p transition followed by ionization by the fundamental FEL pulse, which is a type of x-ray resonance-enhanced multiphoton ionization (REMPI). This resonant phenomenon occurs not only for Ar16+, but also through lower charge states, where multiple ionization competes with decay lifetimes, making x-ray REMPI distinctive from conventional REMPI. With the aid of state-of-the-art theoretical calculations, we explain the effects of x-ray REMPI on the relevant ion yields and spectral profile.

Last updated on 2024-26-11 at 21:29