Related papers: Ionization Potential of the Helium Atom
We present recent results for neutron-rich Helium isotopes obtained from the hyperspherical harmonics method. Ground-state properties, like the binding energy and the point-proton radius are shown for the two-neutron halo nucleus 6He using…
Recent measurements of the ionization energies of the Rydberg $^1P$ states of helium for principal quantum number $n = 24$ and higher present a new challenge to theoretical atomic physics. A long-standing obstacle to high precision atomic…
Light-Ion Trap (LIONTRAP), a high-precision Penning-trap mass spectrometer, was used to determine the atomic mass of $^{4}$He. Here, we report a 12 parts-per-trillion measurement of the mass of a $^{4}$He$^{2+}$ ion, $m(^{4}\text{He}^{2+}$)…
The ionization quenching factor (IQF) is defined as the fraction of energy released by a recoil in a medium through ionization compared with its total kinetic energy. At low energies, in the range of a few keV, the ionization produced in a…
We present kinematically complete theoretical calculations and experiments for transfer ionization in H$^++$He collisions at 630 keV/u. Experiment and theory are compared on the most detailed level of fully differential cross sections in…
Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method. To be specific, precise energy eigenvalues of bound…
The two-neutron RPA model has been used to describe helium isotopes with N (the neutron number) = 4, 6, 7, 8 in their ground and excited states. The properties of all these isotopes are given by a single system of equations so that their…
The process of ionization of a hydrogen atom by a short infrared laser pulse is studied in the regime of very large pulse intensity, in the dipole approximation. Let $A$ denote the integral of the electric field of the pulse over time at…
We calculate the energy levels and successive ionisation potentials (IPs) of ions of the three heaviest known Group 16 and 17 elements using a theoretical approach that combines the linearised coupled-cluster method, configuration…
We report on coulomb explosion imaging of the wavefunction of the quantum halo system He$_2$. Each atom of this system is ionized by tunnelionization in a femto second laser pulse and in a second experiment by single photon ionization…
The ionization energy of D$_2$ has been determined experimentally from measurements involving two-photon Doppler-free vacuum-ultraviolet pulsed laser excitation and near-infrared continuous-wave laser excitation to yield…
We report on a kinematically complete experiment on strong field double ionization of helium using laser pulses with a wavelength of 394\,nm and intensities of $3.5-5.7\times10^{14}\,W/cm^2$. Our experiment reaches the most complete level…
We present a theoretical and experimental investigation of homonuclear ionizing collisions of laser-cooled metastable helium atoms, considering both the fermionic He-3 and bosonic He-4 isotope. The theoretical description combines quantum…
We investigate the properties of the excited state of $^4\mathrm{He}$, $^4\mathrm{He}^*$, within the framework of Efimov physics and its connection to the unitary point of the nuclear interaction. We explore two different approaches to…
We present the first measurement for helium atoms of the tune-out wavelength at which the atomic polarizability vanishes. We utilise a novel, highly sensitive technique for precisely measuring the effect of variations in the trapping…
Relative order \alpha(Z\alpha)^3 shift of the energy levels induced by the vacuum polarization is reexamined for a bound system of two particles with masses m and M. Recent results for hydrogen and for positronium are shown to contain an…
The hyperspherical harmonics (HH) provide a complete basis for the expansion of atomic wave functions, but even for two particles the number of harmonics for a given order is not trivial and, as the number of electrons increases, this…
Electron-electron correlation forms the basis of difficulties encountered in multi-electron systems. Accurate treatment of the correlation problem is likely to unravel some nice physical properties of matter embedded in this correlation. In…
We study the possibility of existence of bound states for two interacting He-4 atoms. It is shown that for some potentials, there exist not only discrete levels but also bands akin to those in the Kronig--Penney model.
We critically examine the current status of theoretical calculations of the energies, the fine structure, and the isotope shift of the lowest-lying states of helium, searching for unresolved discrepancies with experiments. Calculations are…