Seyedreza Larimian

Two-pulse control over double ionization pathways in CO2.

We visualize and control molecular dynamics taking place on intermediately populated states during different sequential double ionization pathways of CO2 using a sequence of two delayed laser pulses which exhibit different peak intensities. Measured yields of CO2 (2+) and of fragment pairs CO(+)/O(+) as a function of delay between the two pulses are weakly modulated by various vibronic dynamics taking place in CO2 (+). By Fourier analysis of the modulations we identify the dynamics and show that they can be assigned to merely two double ionization pathways. We demonstrate that by reversing the sequence of the two pulses it becomes possible to control the pathway which is taken across CO2 (+) towards the final state in CO2 (2+). A comparison between the yields of CO2 (2+) and CO(+)/O(+) reveals that the modulating vibronic dynamics oscillate out-of-phase with each other, thus opening up opportunities for strong-field fragmentation control on extended time scales.

Localizing high-lying Rydberg wave packets with two-color laser fields

We demonstrate control over the localization of high-lying Rydberg wave packets in argon atoms with phase-locked orthogonally polarized two-color laser fields. With a reaction microscope, we measure ionization signals of high-lying Rydberg states induced by a weak dc field and blackbody radiation as a function of the relative phase between the two-color fields. We find that the dc-field-ionization yield of high-lying Rydberg argon atoms oscillates with the relative two-color phase with a period of

Coincidence spectroscopy of high-lying Rydberg states produced in strong laser fields

2\ensuremath{\pi}

Fragmentation of long-lived hydrocarbons after strong field ionization

while the photoionization signal by blackbody radiation shows a period of

Direct observation of laser-induced O 2 + production from CO 2

\ensuremath{\pi}

Enhanced ionization of acetylene in intense laser pulses is due to energy upshift and field coupling of multiple orbitals

. Accompanying simulations show that these observations are a clear signature of the asymmetric localization of electrons recaptured into very elongated (low angular momentum) high-lying Rydberg states after conclusion of the laser pulse. Our findings thus open an effective pathway to control the localization of high-lying Rydberg wave packets.

Localizing high-lying Rydberg wave packets by orthogonally-polarized two-color laser pulses

We demonstrate the detection of high-lying Rydberg states produced in strong laser fields with coincidence spectroscopy. Electron emission after the interaction of strong laser pulses with atoms and molecules is measured together with the parent ions in coincidence measurements. These electrons originate from high-lying Rydberg states with quantum numbers from

Molecular oxygen observed by direct photoproduction from carbon dioxide

n\ensuremath{\sim}20

Localizing High-Lying Rydberg Wave Packets with Orthogonally-Polarized Two-Color Laser Fields

up to

Laser-Induced Oxygen Formation from Carbon Dioxide

n\ensuremath{\lesssim}120