1,593 research outputs found
An echo experiment in a strongly interacting Rydberg gas
When ground state atoms are excited to a Rydberg state, van der Waals
interactions among them can lead to a strong suppression of the excitation.
Despite the strong interactions the evolution can still be reversed by a simple
phase shift in the excitation laser field. We experimentally prove the
coherence of the excitation in the strong blockade regime by applying an
`optical rotary echo' technique to a sample of magnetically trapped ultracold
atoms, analogous to a method known from nuclear magnetic resonance. We
additionally measured the dephasing time due to the interaction between the
Rydberg atoms.Comment: 4 pages, 5 figure
Experimental Studies of NaCs
We present experimental studies of excited electronic states of the NaCs molecule that are currently underway in our laboratory. The optical-optical double resonance method is used to obtain Doppler-free excitation spectra for several excited states. These data are being used to obtain RydbergKlein-Rees (RKR) or Inverse Perturbation Approach (IPA) potential curves for these states. We are also trying to map the bound portion of the 1(a) 3Σ + potential using resolved laser-induced fluorescence and Fourier transform spectroscopy to record transitions into the shallow well. Bound-free spectra from single ro-vibrational levels of electronically excited states to the repulsive wall of the 1(a) 3Σ + state are also being recorded. Using the previously determined excited state potentials, we can fit the repulsive wall of the 1(a) 3Σ + state to reproduce the experimental spectra using LeRoy’s BCONT program. A slightly modified version of BCONT will also be used to fit the relative transition dipole moments, µe(R), as a function of internuclear separation R, for the various bound-free electronic transitions
Field ionization of high-Rydberg fragments produced after inner-shell photoexcitation and photoionization of the methane molecule
We have studied the production of neutral high-Rydberg (HR) fragments from the CH4 molecule at the C 1s -> 3p excitation and at the C 1s ionization threshold. Neutral fragments in HR states were ionized using a pulsed electric field and the resulting ions were mass-analyzed using an ion time-of-flight spectrometer. The atomic fragments C(HR) and H(HR) dominated the spectra, but molecular fragments CHx(HR), x = 1-3, and H-2(HR) were also observed. The production of HR fragments is attributed to dissociation of CH4+ and CH42+ ions in HR states. Just above the C 1s ionization threshold, such molecular ionic states are created when the C 1s photoelectron is recaptured after single or double Auger decay. Similar HR states may be reached directly following resonant Auger decay at the C 1s -> 3p resonance. The energies and geometries of the parent and fragment ions have been calculated in order to gain insight into relevant dissociation pathways. (C) 2015 AIP Publishing LLC
Mexican hat curve for hydrogen- and antihydrogen-states in natural atom H
Molecular band spectra as well as atomic line spectra reveal a left-right
symmetry for atoms (Van Hooydonk, Spectrochim. Acta A, 2000, 56, 2273 and Phys.
Rev. A 66, 044103 (2002). We now extract a Mexican hat shaped or double well
curve from the line spectrum (Lyman ns-series) of natural atom H. An H CSB
theory and its oscillator contribution (1-0.5pi/n)sup(2)/nsup(2) lead to
unprecedented results for antihydrogen physics, ahead of the CERN-AD-project on
artificial antihydrogen.Comment: 4 pages, 1 fig., lecture at Wigner Centennial 2002, Pecs, Hungar
Higgs and gravitational scalar fields together induce Weyl gauge
A common biquadratic potential for the Higgs field and an additional
scalar field , non minimally coupled to gravity, is considered in locally
scale symmetric approaches to standard model fields in curved spacetime. A
common ground state of the two scalar fields exists and couples both fields to
gravity, more precisely to scalar curvature . In Einstein gauge (, often called "Einstein frame"), also is scaled to a constant. This
condition makes perfect sense, even in the general case, in the Weyl geometric
approach. There it has been called {\em Weyl gauge}, because it was first
considered by Weyl in the different context of his original scale geometric
theory of gravity of 1918. Now it seems to get new meaning as a combined effect
of electroweak theory and gravity, and their common influence on atomic
frequencies.Comment: 11 p
- …