Circular Dichroism in Atomic Resonance-Enhanced Few-Photon Ionization

Abstract

We investigate few-photon ionization of lithium atoms prepared in the polarized 2$p$($m_{\ell }=+1$) state when subjected to femtosecond light pulses with left- or right-handed circular polarization at wavelengths between 665 nm and 920 nm. We consider whether ionization proceeds more favorably for the electric field co- or counter-rotating with the initial electronic current density. Strong asymmetries are found and quantitatively analyzed in terms of "circular dichroism" ($CD$). While the intensity dependence of the measured $CD$ values is rather weak throughout the investigated regime, a very strong sensitivity on the center wavelength of the incoming radiation is observed. While the co-rotating situation overall prevails, the counter-rotating geometry is strongly favored around 800 nm due to the 2$p$-3$s$ resonant transition, which can only be driven by counter-rotating fields. The observed features provide insights into the helicity dependence of light-atom interactions, and on the possible control of electron emission in atomic few-photon ionization by polarization-selective resonance enhancement.

References in corpus (9)

• Ultrafast Preparation and Detection of Ring Currents in Single Atoms
• Observation of enhanced chiral asymmetries in the inner-shell photoionization of uniaxially oriented methyloxirane enantiomers
• Compact 200 kHz HHG source driven by a few-cycle OPCPA
• Quantum control of photoelectron circular dichroism
• Using circular dichroism to control energy transfer in multi-photon ionization
• Electron and recoil ion momentum imaging with a magneto-optically trapped target
• Ionization and excitation of the excited hydrogen atom in strong circularly polarized laser fields
• An all-optical atom trap as a target for MOTRIMS-like collision experiments
• Photo-ionization of polarized lithium atoms out of an all-optical atom trap: A complete experiment

Cited by in corpus (7)

• Photoelectron momentum distributions in the strong-field ionization of atomic hydrogen by few-cycle elliptically polarized optical pulses
• Two-path interference in the resonance-enhanced few-photon ionization of atoms
• Topical Review: Extracting Molecular Frame Photoionization Dynamics from Experimental Data
• Circular Dichroism in Multiphoton Ionization of Resonantly Excited Helium Ions near Channel Closing
• Polarization effects in the total rate of biharmonic $\omega +3\omega$ ionization of atoms
• Carrier-envelope phase effects in one- and two-photon directional photoionization of non-isotropic atomic states
• Magnetic Dichroism in Few-Photon Ionization of Polarized Atoms