We have observed resonant phenomena in the intense-field ionization of argon that do not easily fit into the standard models of above-threshold ionization. High-resolution angleresolved measurements of the energy region around 6–10 times the ponderomotive potential UP in the ATI electron spectrum show at least three separate series of peaks, each with a distinct intensity threshold for their on...

An in-depth experimental investigation into the use of photoelectron spectroscopy to probe the dynamics of a dissociative intermediate state is reported here. More than 70 velocity-mapped photoelectron images were acquired from either one-colour or two-colour two-photon ionization processes, covering the energy range from the ionization limit of CH3I to about 3600 cm 1 above the IP. Numerous au...

For the prototypical conjugated organic molecules pentacene and perfluoropentacene, we demonstrate that the surface termination of ordered organic thin films with intramolecular polar bonds (e.g., -H versus -F) can be used to tune the ionization energy. The collective electrostatics of these oriented bonds also explains the pronounced orientation dependence of the ionization energy. Furthermore...

We investigate the first example of self-consistent impact ionization fronts propagating at relativistic speeds and involving interacting, high-energy electrons. These fronts, which we name relativistic runaway ionization fronts, show remarkable features such as a bulk speed within less than one percent of the speed of light and the stochastic selection of high-energy electrons for further acce...

It is shown that recently measured cross sections for double ionization of negative ions (H−, O−, and C−) possess a universal shape when plotted in suitable dimensionless units. The shape can be represented with a simple analytical function, following the same principles as it has been done in establishing a universal shape function for single ionization [Rost and Pattard 1997 Phys. Rev. A 55 R...

Neutral atoms and clusters desorbed from a solid germanium surface by ion bombardment are detected by laser postionization and time-of-flight mass spectrometry. Two different photoionization schemes are compared which are generally believed to be candidates for the 'soft' ionization of polyatomic species without significant photon induced fragmentation. First, a single photon ionization process...

Context. Low-energy cosmic rays are a fundamental source of ionization for molecular clouds, influencing their chemical, thermal and dynamical evolution. Aims. The purpose of this work is to explore the possibility that a low-energy component of cosmic-rays, not directly measurable from the Earth, can account for the discrepancy between the ionization rate measured in diffuse and dense interste...

A pulsed crossed beam technique is used to measure ionization cross-sections of metallic atoms. Relative values of cross-sections of single, double and triple ionization of magnesium have been successfully measured with good accuracy over the 0-700 eV range. Absolute values of cross-sections have been obtained by normalization to a theoretical value at high electron energy. Results are compared...

In ultra-high sensitive APDs, a vibrate of temperature might bring a fatal decline of the multiplication performance. Conventional method to realize a temperature-stable APD focuses on the optimization of device structure, which has limited effects. While in this paper, a solution by reducing the carrier scattering rate based on an GaN/AlN periodically-stacked structure (PSS) APD is brought out...

We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossing...