Diffraction using laser-driven broadband electron wave packets

Abstract

Directly monitoring atomic motion during a molecular transformation with atomic-scale spatio-temporal resolution is a frontier of ultrafast optical science and physical chemistry. Here we provide the foundation for a new imaging method, fixed-angle broadband laser-induced electron scattering, based on structural retrieval by direct one-dimensional Fourier transform of a photoelectron energy distribution observed along the polarization direction of an intense ultrafast light pulse. The approach exploits the scattering of a broadband wave packet created by strong-field tunnel ionization to self-interrogate the molecular structure with picometre spatial resolution and bond specificity. With its inherent femtosecond resolution, combining our technique with molecular alignment can, in principle, provide the basis for time-resolved tomography for multi-dimensional transient structural determination.

Observation of ionization enhancement in two-color circularly polarized laser fields

“…When the HHG process is properly phase matched, a bright coherent beam of extreme ultraviolet (EUV) or soft X-ray light is generated [6][7][8][9][10], which can be used to uncover coupled dynamics in materials with femtosecond-to-attosecond temporal resolution [11][12][13][14][15], and can also be used for high-resolution imaging [16][17][18][19]. Alternatively, if the electron does not recombine upon re-encountering the ion it may rescatter from the ion, encoding information about the sub-ångström and sub-femtosecond structure of the scattering potential into the photoelectron momentum distribution [20][21][22].…”

Static Coherent States Method: One- and Two-Electron Laser-Induced Systems with Classical Nuclear Dynamics

“…Current theoretical treatments largely focus on electronic dynamics. However, recent experiments have demonstrated the retrieval of bond distances in simple diatomic molecules [6] and control over the ultrafast dissociation process and resolution of bond dynamics of a polyatomic molecule using laser-induced electron diffraction (LIED) [7]. To fully understand molecular dynamics during interaction with a strong laser pulse, it is therefore essential to develop a theory that takes into account the bond dynamics and dissociation process and thereby accurately describes nuclear, as well as electronic, motion.…”

High power multi-color OPCPA source with simultaneous femtosecond deep-UV to mid-IR outputs

“…Although the transition of strong-field ionization from the multiphoton to tunneling regime has been studied previously [27,28], in this Letter we show the first experimental investigation from the near-IR to the true mid-IR spectral region (λ > 3 μm) driven by a single light source at an unprecedented repetition rate of 160 kHz. The high repetition rate of the source is a key enabling factor to study low cross section processes, such as electron correlation in double or multiple ionization or recollision events, such as laser induced electron diffraction (LIED) [29,30] and broadband laser-driven electron scattering [31]. These two examples are strong-field imaging techniques of the structure of the nucleus, which allow unprecedented spatial resolutions in the sub-Angstrom regime.…”