P Grafstrom

Two-photon excitation of atomic oxygen in a flame

Atomic oxygen has been detected in a lean acetylene/oxygen flame using the 2p43P2-2p33p3P two-photon transition at 226 nm and fluorescence detection at 845 nm.

Spatially resolved temperature measurements in a flame using laser-excited two-line atomic fluorescence and diode-array detection.

Spatially resolved temperature measurements in a CH(4)-air flame have been achieved using two-line laser-induced fluorescence from indium atoms seeded to the flame.

Natural Radiative Lifetimes In the Perturbed 6snd 1d2 Sequence of Barium

Natural radiative lifetimes in the perturbed 6s n s1D2 (n=12−30) sequence of barium have been measured using the PUMOLS (PUlse-MOdulated Laser Spectroscopy) method, which incorporates pulse-modulation of a CW dye-laser beam and delayed coincidence techniques. Principal perturbers are the 5d 7d3F2 and1D2 states. Lifetimes were also measured for these shortlived valence states, which through configuration mixing cause drastic decreases in lifetime values in the region of perturbation of the 6s n d1D2 sequence. Two-step laser excitation from the ground 6s21S0 state via the 6s 6p1P1 state was employed. Special care was taken to determine the influence of black-body radiation transitions on the measured lifetimes.

Perturbation of the Ba 6sns 1so Sequence By the 5d7d 3po State, Probed By Lifetime Measurements

The 6sn s 1S0 sequence of Ba is strongly perturbed around n=18 by the 5d7d 3P0 doubly excited state. The authors have probed the configuration mixing by observing the strong decrease in the measured 1S0 lifetimes around the short-lived valence perturber state. The measurements have enabled the authors to resolve the problem of the designation of the studied states. Wavefunctions obtained from multi-channel quantum-defect theory were used to calculate theoretical lifetimes in good agreement with the experimental values.

Hyperfine structure and isotope shift of highly excited barium-I states

High-resolution laser-spectroscopy measurements of hyperfine structure and isotope shifts were performed for the 6snd1D2 sequence of Ba-I in the regionn=12–24. Stepwise laser excitations of a collimated atomic beam were used. A strong influence on the hyperfine structure is observed at the perturbation atn=14, caused by interaction with the 5d7d configuration. Whereas the isotope shift for the even isotopes stays essentially constant with increasingn, the odd isotopes exhibit a strong change, indicating hyperfine-induced shifts.

Doppler-Free Laser Spectroscopy Measurements on a Ne Discharge for Determination of 22Ne-20Ne Isotope Shifts

We have used Doppler-free polarization spectroscopy, intermodulated fluorescence and intermodulated optogalvanic spectroscopy for measuring isotope shifts in 6 Ne lines connecting the 2p53s and 2p53p configurations. The measurements were performed on two different hollow cathodes. For the 5852, 5882, 5945, 5976, 6143 and 6164 A lines the 22Ne-20Ne isotope shift was found to be 2300(15), 1740(2), 1717(3), 1728(5), 1669(4) and 1663(5) MHz, respectively. These results are in fair agreement with previous optical spectroscopy data.