The production and detection of highly excited states

Angelo A. Lamola, William R. Ware

Yiyan Huang

Production and state-selective detection of ultracold molecular rubidium (85Rb2) in the singlet ground state and the metastable triplet state are described. Ultracold 85Rb2 molecules are produced via photoassociation followed by radiative decay. State-selective detection of high-ν ground-state and metastable-state molecules is carried out by resonant Two-photon ionization (R2PI) with a pulsed laser. The spectra of both the ground singlet and metastable triplet states are investigated. Spectroscopy of several intermediate excited states, some of which are observed for the first time, is also studied. Mixing between excited singlet and triplet states is observed in both the singlet and triplet spectra. A proposal for producing ν = 0 ground-state molecules by utilizing this singlet-triplet mixing is given. Magnetic trapping and filtering of metastable triplet-state molecules is also described, and a scheme for optical trapping of molecules is proposed.^

Daniel Kleppner

Anthony F. J. van Raan, G. Baum, Wilhelm Raith

Very highly excited p states of Cs with principal quantum numbers 30<or=n<or=85 were produced by one-step photoexcitation with frequency-doubled light from a flash-lamp-pumped dye laser. Field ionization was employed for selective detection. Ionization occurs at field strengths E>or=E min with a sharp threshold. The relation E min (n*) varies as (n*) -4 was verified over a wide range. Two-photon excitation to a very high state via a virtual intermediate state leads to immediate ionization of most of the excited atoms; in this case the ion signal as a function of the light intensity I is not proportional to I k , k>or=2, whereas a direct two-photon transition into the continuum yields proportionality with I 2 .

Boris Michailovich Smirnov

G. B. McMillian

A frequency stabilized ring dye laser, with a linewidth of (TURN)250 kHz, has been utilized to selectively excite Rb(N('2)S, N('2)D) states in the range N = 20 - 100 by a two photon process. The highly excited atoms were detected by the technique of electric field ionization. Excited states with (VBAR)M(,L)(VBAR) < 3 have been observed to ionize along predominantly adiabatic paths and states with (VBAR)M(,L)(VBAR) (GREATERTHEQ) 3 have been observed to ionize along predominantly diabatic paths for the range of N investigated. The electric field dependence of the ionization threshold has been determined to be in good agreement with that calculated from a simple model based on the energies and ionization rates of hydrogen.\nCollisions between highly excited rubidium atoms and neutral xenon atoms, which result in a change in the N and L of the excited state of the rubidium atom, have been investigated. The N of the final state has been shown to be limited to those states which lie closest in energy to the initial state, in good agreement with theory. The distribution of L of the final states has been shown to be completely statistical or biased towards production of high L. The distribution of final L is definitely not biased toward production of states with low values of L.