Threshold fragmentation under dipole forces

Multiphoton above threshold effects in strong-field fragmentation

We present a study of multiphoton dissociative ionization from molecules. By solving the time-dependent Schrödinger equation for H$_2^+$ and projecting the solution onto double continuum scattering states, we observe the correlated electron-nuclear ionization dynamics in detail. We show --- for the first time --- how multiphoton structure prevails as long as the energies of all fragments are accounted for. Our current work provides a new avenue to analyze strong-field fragmentation that leads to a deeper understanding of the correlated molecular dynamics.

Initial state dependence in multi-electron threshold ionization of atoms

It is shown that the geometry of multi-electron threshold ionization in atoms depends on the initial configuration of bound electrons. The reason for this behavior is found in the stability properties of the classical fixed point of the equations of motion for multiple threshold fragmentation. Specifically for three-electron break-up, apart from the symmetric triangular configuration also a break-up of lower symmetry in the form of a T-shape can occur, as we demonstrate by calculating triple photoionization for the lithium ground and first excited states. We predict the electron break-up geome…

Electron-impact ionization and ionic fragmentation of O$_{2}$ from threshold to 120 eV energy range

We study the electron-impact induced ionization of O$_{2}$ from threshold to 120 eV using the electron spectroscopy method. Our approach is simple in concept and embodies the ion source with a collision chamber and a mass spectrometer with a quadruple filter as a selector for the product ions. The combination of these two devices makes it possible to unequivocally collect all energetic fragment ions formed in ionization and dissociative processes and to detect them with known efficiency. The ion source allows to vary and tune the electron-impact ionization energy and the target-gas pressure. W…

Near-threshold bound states of the dipole-dipole interaction

We study the two-body bound states of a model Hamiltonian that describes the interaction between two field-oriented dipole moments. This model has been used extensively in many-body physics of ultracold polar molecules and magnetic atoms, but its few-body physics has been explored less fully. With a hard-wall short-range boundary condition, the dipole-dipole bound states are universal and exhibit a complicated pattern of avoided crossings between states of different character. For more realistic Lennard-Jones short-range interactions, we consider parameters representative of magnetic atoms and…

Dipole-Magnetic Photo-Recombination in Ultracold Hydrogen Plasma

The cross section of dipole-magnetic photodisintegration of the negative hydrogen ion has been calculated within the framework of an effective-range theory. The dipole-magnetic cross section of photodetachment within the very narrow range of energy near the process threshold dominates over the dipole-electric one. It has been shown that in ultracold hydrogen plasma at temperatures below kT=3.29.10-4 K the dipole-magnetic photo-recombination becomes a main mechanism of electron capture by hydrogen atoms.

Jacobi-Anger方法与鞍点方法在超阈值离子化处理中的比较

Comparison between Jacobi-Anger and saddle point methods to treat Above-threshold ionization

本文比较了Jacobi-Anger方法与鞍点方法在强场离子化中的应用，揭示了偶极近似与非偶极效应在光谱解析中的影响及方法选择对预测的重要性。