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Second-order [O(k^2), k=omega/c] nondipole effects in soft-x-ray photoemission are demonstrated via an experimental and theoretical study of angular distributions of neon valence photoelectrons in the 100--1200 eV photon-energy range. A newly derived theoretical expression for nondipolar angular distributions characterizes the second-order effects using four new parameters with primary contributions from pure-quadrupole and octupole-dipole interference terms. Independent-particle calculations of these parameters account for a significant portion of the existing discrepancy between experiment and theory for Ne 2p first-order nondipole parameters.
Comment: 13 pages, LaTeX; dedicated to Prof. H.-J. Kluge on the occasion of his 65th birthday, to appear in Int. J. Mass. Spectrometry
This thesis demonstrates the experimental implementation of a homodyne interference technique to detect weak atomic transitions. The demonstration of the technique uses two pathways to excite the cesium atom from its ground state to an excited state. One is a Stark-induced transition that is regulated by controlling a dc field across the cesium atoms. This is excited by a 411 nm laser field. A two-photon transition excited by an 822 nm laser field concurrently excites the same transition. The simultaneous excitation of the two pathways results in a quantum interference of the transition amplitudes. Phase modulating one of the beams gives rise to an amplitude modulation of the net excitation rate resulting in an amplitude modulated fluorescence signal. We observe the fluorescence at 794.6 nm due to the decay of the excited state to the ...
The system of highly excited hydrogen in combined strong ac and dc electric fields is examined. It is shown that the production and maintainence of effectively one-dimensional states is plausible in this system. The threshold of global classical chaos is calculated using the resonance overlap method. In the microwave regime, the ionization by chaos is compared with the ionization by tunneling in the dc field, showing the limits on the dc field in order for chaotic effects to be detectable in experiments. The investigation of a new regime of infrared, visible, and ultraviolet ac fields is proposed and pursued. The theory of quantum localization of classical chaos is motivated, and it is shown to come strongly into play in the proposed regime. A criterion for the appearance of spectral effects due to chaos, based on the localization theo...
Comment: 14 pages, 5 figures (Figs.2-5 have "a" and "b" parts), Phys.Rev.A accepted for publication. Fig.2b is presented correctly
Comment: 10 pages, 8 figures; discussions slightly modified and an additional figure inserted for clarity
The intercombination line of Strontium at 689nm is successfully used in laser cooling to reach the photon recoil limit with Doppler cooling in a magneto-optical traps (MOT). In this paper we present a systematic study of the loading efficiency of such a MOT. Comparing the experimental results to a simple model allows us to discuss the actual limitation of our apparatus. We also study in detail the final MOT regime emphasizing the role of gravity on the position, size and temperature along the vertical and horizontal directions. At large laser detuning, one finds an unusual situation where cooling and trapping occur in the presence of a high bias magnetic field.
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