L. Broström

Theoretical potential curves for the A 2Π and X 2Σ+ states of NO2+ and an experimental search for the A–X transition

Abstract Potential curves for the X 2 Σ + and A 2 Π states of NO 2+ have been calculated using large ANO basis sets including g functions and CASSCF/second-order ACPF methods. On the basis of these calculations resonant photodissociation of NO 2+ via the A 2 Π−X 2 Σ + transition has been searched for by means of a collinear fast ion beam laser apparatus. The failure to observe the A–X transition is discussed.

High-resolution spectroscopy of the A 1Πu−X 1Σ+g (6, 1) band in N2+2

Abstract Resonances in the photodissociation spectrum of N 2+ 2 have been further experimentally investigated using a fast ion beam in combination with high-resolution laser spectroscopy. A number of resonances in the photofragmentation cross section belonging to the Q branch of the (6, 1) band of the A 1 Π u −X 1 Σ + g transition has been recorded. Vacuum wavenumbers of this band as well as molecular constants of the upper state are presented here. Two of the lines of the (6, 1) transition were found to deviate some tenths of a wavenumber from their expected positions, indicating some possible weak perturbation.

Dissociative recombination of H2+ studied in CRYRING

Dissociative recombinations of H2+ with electrons has been studied in the ion storage ring CRYRING at the Manne Siegbahn Labooratory. The H2+ ions were stored at an energy of 6 MeV/u and phase-space cooled by 3.25 keV electrons. After 20s of storage and cooling, dissociative recombination was studied over the energy range 0.005-60eV. Advantage was taken of the new electron cooler design, which allows for a tenfold decrease of the transverse electron temperature. Resonance structures in the low-energy cross section were clearly observed and found in quite good agreement with theoretical results.

Measurements of isotope shift in Eu II

The isotope shift between singly-charged Eu-151 and Eu-153 in the 4f(7)(S-8 degrees)6s S-9 degrees(4) - 4f(7)(S-8 degrees)6p(1/2) J = 4 transition at 4129 Angstrom has been measured using fast ion beam-laser technique. This Eu line has attracted interest

Laser probing of ions in a storage ring: A method for selective determination of lifetimes of metastable states

A collinear laser probing technique is introduced for use in ion storage rings. This method can be used for high resolution studies of the decay properties of metastable states in ions. An experiment on singly charged xenon utilizing this technique is presented. By selective excitation of individual hyperfine states a drastic hyperfine induced quenching was observed. Systematic effects from ion beam neutralization in the rest gas and mixing effects occurring in the bending magnets are discussed.

Hyperfine structure measurements in Kr II

The fast ion beam laser technique has been utilized to study the hyperfine structure in the transitions 4d4D7/2-5p4D72/0 at 6420 Å and 4d4D7/2-5p4D52/0 at 6303 Å in singly-charged krypton. The magnetic dipole and electric quadrupole hyperfine constants have been extracted for the upper levels of the transitions.

Studies of doubly charged molecular ions by means of ion photofragment spectroscopy

Some recent work on doubly charged molecular ions is described. The method of ion photofragment spectroscopy has been applied to the N22+ and NO2+ dications. The (8,2) band of the A 1

Branching processes in the dissociative recombination of H3

PIu - (Chi) 1(Sigma) g+ transition was recorded at high spectral resolution. Line positions and linewidths were measured. It was found that levels of f-symmetry of the A state were more strongly predissociated than levels of e-symmetry. Attempts to observe structured photodissociation of NO2+, despite aid from large scale ab initio calculations, failed.