The E 1Σ+g ‘‘shelf ’’ state of the 7Li2 molecule was investigated using a pulsed optical optical double resonance technique. The measurements cover the vibrational levels in the range 0≤v≤29 including the shelf region around 13≤v≤15. Molecular constants have been determined. Using an inverted perturbation approach, an effective potential energy curve has been generated within the adiabatic approximation whose quantum mechanical energy eigenvalues reproduce all the measured term values to within 0.113 cm−1 for the range 0≤v≤23 and 0≤J≤47.

The results of pulsed optical–optical double resonance spectroscopic studies of the E 1S+g and F 1S+g states of 7Li2 are presented. Observations were carried out on the v = 0 through v = 30 levels of the F 1S+g state, representing about 60% of the dissociation energy. A set of Dunham molecular constants was derived and an RKR potential was generated. Franck–Condon factors were determined for the range of observed vibrational levels. The spectroscopic results on the E 1S+g state are preliminary and are included because of a probable homogeneous anticrossing between it and the F 1S+g state. It is suggested that the E 1S+g state correlates with the (2 2S)+(3 2S) atomic lithium states while the F 1S+g correlates with the (2 2P)+(2 2P) states.

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Catadioptric step-and-scan lithography offers specific advantages over step-and-repeat all-refractive (dioptric) systems as resolution requirements drive to 0.25pm in volume production. For the Micrascan family ofstep-and-scan tools this step in the evolutionary path from 0.35.tm to 0.25.tm has involved changes to both the projection optics and illumination system.

Penning and associative ionization of mercury by collision with metastable rare gas atoms We report absolute cross sections for Hg(63P,) + Hg(63P0) associative ionization and Hgz + e-dissociative recombination in mercury vapor, following saturation of the 253.7-nm transition using pulsed laser excitation. The quantitative time dependencies of all relevant species were determined by combining this information with measurements of the total Hg( 63P, ) density and the total electron current following the laser pulse. The electron temperature associated with our measurement of k,, is 298 K. The measured values of k,, = (2.5 f 0.6) X lo-*cm 3 -' and kDR = (4.4 f 1.1) X lo'-%m3 s-' are 3.5 times s smaller and 10.5 times larger, respectively, than those previously reported in cw and discharge flow studies.