[en] We report a measurement of the branching ratio for production of 5d_3/2 ions in various m_j states following the autoionization of the (6_p1/2nd_5/2)J=M_J=3 states of barium in an electric field. By detecting the population in different ion states, rather than the electron distribution, we are able to measure the decay routes even in the presence of an electric field. These branching ratios show pronounced new structure, even at fields as low as 30 V/cm

[en] We have constructed an ellipsoidal electron mirror from a pair of molded stainless steel grids in a fashion similar to the parabolic mirror constructed by Trevor et al.. The ellipsoidal geometry provides superior collection efficiency while maintaining good temporal resolution for our small flight path of 19 cm. We will present data showing the use of this analyzer to separate electrons produced in various channels following the decay of doubly-excited autoionizing states of barium

[en] We report a measurement of the energy dependence of the branching ratios for autoionization of the (6p_1/2nd_5/2)J=M_J=3 states of barium into the 5d_3/2ε ell continuum channels by monitoring the population in each m_j state of the 5d_3/2 residual ion. We use polarization sensitive laser-induced-fluorescence to detect the ion populations. Near the energy of the 6p_1/2ng J = 3 resonances, the doubly-excited barium atom produces nearly 40% of its population in the 5d_3/2εh_9/2 channel, corresponding to an exchange of at least 3 units of orbital angular momentum

[en] We have constructed MQDT parameters for the odd parity, J = 3 autoionizing states of barium by using single configuration wavefunctions to calculate Slater integrals, and transforming them into an MQDT R matrix. We then compared our values with the measured branching ratios for autoionization into the 5d_3/2 ion channels to modify the calculated values. For states converging on the lower, 6p_1/2 ion limit, the branching ratios have a complex dependence on energy, so that a curve fitting process has considerably more reliability than one which just uses the resonance energy values. This provides a convenient way to characterize the complex spectra and branching ratios for multi-electron atoms

[en] A new measurement has been made of the proton magnetic moment in a spherical sample of water. The result is obtained to an estimated 10 ppb using an NMR technique

[en] This paper addresses the study of two-electron Rydberg atoms. With Multichannel Quantum Defect Theory (MQDT), there is a technique for characterizing a spectra in terms of a small number of parameters. A survey of some important effects specific to two-electon Rydberg states, using primarily the alkaline earth atoms for examples, is made. The remainder of the paper deals with a discussion of the electron-electron interaction, including some of the basic points of MQDT. Energy exchange between two electrons is also addressed

[en] The authors have simply determined autoionizing rates for states that have autoionization-induced linewidths smaller than the linewidth of their laser. By increasing our laser power to depletion-broaden the transition they have increased the apparent width of the transition beyond the laser's linewidth. The natural autoionization width can then be inferred from the laser power required to depletion-broaden the transition

[en] The authors have measured the collisional depopulation cross sections of Na s states from n = 6 to 11. The maximum cross sections observed for He, Ar, and Xe, respectively, are approx. 20, 20, and 100 A². The cross sections rise from approx. 0.1 A² at n approx. 6 to a plateau at n approx. 10. The small size of the cross sections suggests that the process proceeds via the interaction of the Na⁺ core with the rare-gas atom. Specifically, this short-range interaction produces a transient dipole on the rare-gas atom which efficiently couples Na states of different n. This is an entirely different mechanism than that responsible for the collisional l mixing previously reported

[en] Using selective field ionization (SFI) of Na Rydberg atoms we have detected the 300 ⁰K blackbody radiation which induces the Na transitions 17s→17p, 18s→18p, 17d→18p, and 17d→18f frequencies of 27.3, 22.8, 7.4, and 41.6 cm^-1, respectively. Investigation of the probable collisional effects show that they are negligible at 300 ⁰K and allow us to project temperatures of <25 ⁰K for Rydberg-atom long-wave detectors

[en] In Na, the energy gap ΔE between the n,d state and the n,l > 2 states is ten times larger than ΔE between n,f and the n,l > 3 states. To investigate the effect of this difference on the d- and f-state l-mixing cross sections, sigma/sub d/ and sigma/sub f/, we have recently carried out experiments to measure sigma/sub d-f/, the l-mixing cross sections for a microwave-induced mixture of d and f states. Using the previously measured values of sigma/sub d/, we have derived values of sigma/sub f/ which have the same n dependence as sigma/sub d/. sigma/sub f/ is larger than sigma/sub d/ for Ne, but smaller for He and Ar. In addition, we have analyzed the final states after one collision with Ar using selective field ionization of the 17l states and have observed that after one collision all the l states are equally populated indicating that there are no Δl selection rules for the process. This confirms the earlier suggestion that l mixing is caused by a short-range interaction