11 research outputs found
Single-shot velocity-map imaging of attosecond light-field control at kilohertz rate
High-speed, single-shot velocity-map imaging (VMI) is combined with carrier-
envelope phase (CEP) tagging by a single-shot stereographic above-threshold
ionization (ATI) phase-meter. The experimental setup provides a versatile tool
for angle-resolved studies of the attosecond control of electrons in atoms,
molecules, and nanostructures. Single-shot VMI at kHz repetition rate is
realized with a highly sensitive megapixel complementary metal-oxide
semiconductor camera omitting the need for additional image intensifiers. The
developed camerasoftware allows for efficient background suppression and the
storage of up to 1024 events for each image in real time. The approach is
demonstrated by measuring the CEP-dependence of the electron emission from ATI
of Xe in strong (≈1013 W/cm2) near single-cycle (4 fs) laser fields. Efficient
background signal suppression with the system is illustrated for the electron
emission from SiO2nanospheres
Field propagation-induced directionality of carrier-envelope phase-controlled photoemission from nanospheres
Near-fields of non-resonantly laser-excited nanostructures enable strong localization of ultrashort light fields and have opened novel routes to fundamentally modify and control electronic strong-field processes. Harnessing spatiotemporally tunable near-fields for the steering of sub-cycle electron dynamics may enable ultrafast optoelectronic devices and unprecedented control in the generation of attosecond electron and photon pulses. Here we utilize unsupported sub-wavelength dielectric nanospheres to generate near-fields with adjustable structure and study the resulting strong-field dynamics via photoelectron imaging. We demonstrate field propagation-induced tunability of the emission direction of fast recollision electrons up to a regime, where nonlinear charge interaction effects become dominant in the acceleration process. Our analysis supports that the timing of the recollision process remains controllable with attosecond resolution by the carrier-envelope phase, indicating the possibility to expand near-field-mediated control far into the realm of high-field phenomena
Field propagation-induced directionality of carrier-envelope phase-controlled photoemission from nanospheres
Near-fields of non-resonantly laser-excited nanostructures enable strong localization of ultrashort light fields and have opened novel routes to fundamentally modify and control electronic strong-field processes. Harnessing spatiotemporally tunable near-fields for the steering of sub-cycle electron dynamics may enable ultrafast optoelectronic devices and unprecedented control in the generation of attosecond electron and photon pulses. Here we utilize unsupported sub-wavelength dielectric nanospheres to generate near-fields with adjustable structure and study the resulting strong-field dynamics via photoelectron imaging. We demonstrate field propagation-induced tunability of the emission direction of fast recollision electrons up to a regime, where nonlinear charge interaction effects become dominant in the acceleration process. Our analysis supports that the timing of the recollision process remains controllable with attosecond resolution by the carrier-envelope phase, indicating the possibility to expand near-field-mediated control far into the realm of high-field phenomena.112926Ysciescopu
Attosecond chronoscopy of electron scattering in dielectric nanoparticles
The scattering of electrons in dielectric materials is central to laser nanomachining1, light-driven electronics2 and radiation damage3-5. Here, we demonstrate real-time access to electron scatteringbyimplementingattosecondstreakingspectroscopy on dielectric nanoparticles: photoelectrons are generated inside the nanoparticles and both their transport through the material and photoemission are tracked on an attosecond timescale. We develop a theoretical framework for attosecond streaking spectroscopy in dielectrics and identify that the presence of the internal field inside the material cancels the influence of elastic scattering, enabling the selective characterization of the inelastic scattering time. The approach is demonstrated on silica nanoparticles, where an inelastic mean-free path is extracted for 20-30 eV. Our approach enables the characterization of inelastic scattering in various dielectric solids and liquids, including water, which can be studied in the form of droplets
Carrier–envelope phase-tagged imaging of the controlled electron acceleration from SiO 2
Waveform-controlled light fields offer the possibility of manipulating
ultrafast electronic processes on sub-cycle timescales. The optical lightwave
control of the collective electron motion in nanostructured materials is key
to the design of electronic devices operating at up to petahertz frequencies.
We have studied the directional control of the electron emission from 95 nm
diameter SiO2 nanoparticles in few-cycle laser fields with a well-defined
waveform. Projections of the three-dimensional (3D) electron momentum
distributions were obtained via single-shot velocity-map imaging (VMI), where
phase tagging allowed retrieving the laser waveform for each laser shot. The
application of this technique allowed us to efficiently suppress background
contributions in the data and to obtain very accurate information on the
amplitude and phase of the waveform-dependent electron emission. The
experimental data that are obtained for 4 fs pulses centered at 720 nm at
different intensities in the range (1–4) × 1013 W cm−2 are compared to quasi-
classical mean-field Monte-Carlo simulations. The model calculations identify
electron backscattering from the nanoparticle surface in highly dynamical
localized fields as the main process responsible for the energetic electron
emission from the nanoparticles. The local field sensitivity of the electron
emission observed in our studies can serve as a foundation for future research
on propagation effects for larger particles and field-induced material changes
at higher intensities