QED Effect on the Nuclear Magnetic Shielding of ^{3}He.

The leading quantum electrodynamic corrections to the nuclear magnetic shielding in one- and two-electron atomic systems are obtained in a complete form, and the shielding constants of ^{1}H, ^{3}He^{+}, and ^{3}He are calculated to be 17.735 436(3)×10^{-6}, 35.507 434(9)×10^{-6}, and 59.

Charge-Transfer-Induced Predissociation in Rydberg States of Molecular Cations: MgAr.

Very little is known about the Rydberg states of molecular cations, i.e., Rydberg states having a doubly charged ion core.

Spectroscopic characterization of a thermodynamically stable doubly charged diatomic molecule: MgAr.

Although numerous doubly positively charged diatomic molecules (diatomic dications) are known from investigations using mass spectrometry and ab initio quantum chemistry, only three of them, NO, N and DCl, have been studied using rotationally resolved optical spectroscopy and only about a dozen by vibrationally resolved double-ionization methods. So far, no thermodynamically stable diatomic dication has been characterized spectroscopically, primarily because of experimental difficulties associated with their synthesis in sufficient densities in the gas phase. Indeed, such molecules typically involve, as constituents, rare-gas, halogen, chalcogen, and metal atoms.

Complete characterization of the 3p Rydberg complex of a molecular ion: MgAr. I. Observation of the Mg(3p)Ar B state and determination of its structure and dynamics.

We report on the experimental observation of the BΣ state of MgAr located below the Mg(3p P) + Ar(S) dissociation asymptote. Using the technique of isolated-core multiphoton Rydberg-dissociation spectroscopy, we have recorded rotationally resolved spectra of the BΣ(v') ← XΣ(v″ = 7) transitions, which extend from the vibrational ground state (v' = 0) to the dissociation continuum above the Mg(3p P) + Ar(S) dissociation threshold. The analysis of the rotational structure reveals a transition from Hund's angular-momentum-coupling case (b) at low v' values to case (c) at high v' values caused by the spin-orbit interaction.

Complete characterization of the 3p Rydberg complex of a molecular ion: MgAr. II. Global analysis of the AΠ and BΣ (3p) states.

We report a global study of the 3p Rydberg complex of the MgAr molecular ion. High-resolution spectroscopic data on the two spin-orbit components of the A electronic state were obtained by isolated-core multiphoton Rydberg-dissociation spectroscopy up to vibrational levels as high as v' = 29, covering more than 90% of the potential wells. Accurate adiabatic potential-energy functions of the A and B states, which together form the 3p Rydberg complex, were obtained in a global direct-potential-fit analysis of the present data and the extensive data on the B state reported in Paper I [D.

Determination of the Interaction Potential and Rovibrational Structure of the Ground Electronic State of MgAr Using PFI-ZEKE Photoelectron Spectroscopy.

The interaction potential characterizing the ground electronic state of MgAr has been determined from the photoelectron spectrum recorded from the a Π metastable state of MgAr at high resolution by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy. The photoelectron spectrum provides information on the first ten vibrational levels of MgAr and leads to the determination of the adiabatic ionization energy of metastable MgAr (38 742.3(20) cm), the ground state dissociation energy of MgAr (1254(60) cm), and to the characterization of the rovibrational photoionization dynamics of MgAr.

Nonlocal Polarization Feedback in a Fractional Quantum Hall Ferromagnet.

In a quantum Hall ferromagnet, the spin polarization of the two-dimensional electron system can be dynamically transferred to nuclear spins in its vicinity through the hyperfine interaction. The resulting nuclear field typically acts back locally, modifying the local electronic Zeeman energy. Here we report a nonlocal effect arising from the interplay between nuclear polarization and the spatial structure of electronic domains in a ν=2/3 fractional quantum Hall state.