We report the sudden and spontaneous evolution of an initially correlated gas of repulsively interacting Rydberg atoms to an ultracold plasma. Under continuous laser coupling we create a Rydberg ensemble in the strong blockade regime, which at longer times undergoes an ionization avalanche. By combining optical imaging and ion detection, we access the full information on the dynamical evolution...

The ionization behavior of the high Rydberg states of bis(eta(6)-benzene)chromium in the presence of ac and/or dc fields has been explored. The application of an ac scrambling field at the time of laser excitation lengthens the lifetime of the Rydberg state by almost two orders of magnitude. The lifetime enhancement by the scrambling field is much more effective for n<100 than it is for n>100 R...

We observe individual dark-state polaritons as they propagate through an ultracold atomic gas involving Rydberg states coupled via an electromagnetically induced transparency resonance. Strong long-range interactions between Rydberg excitations give rise to a blockade between polaritons, resulting in large optical nonlinearities and modified polariton number statistics. By combining optical ima...

We report on the use of an efficient stepwise-resonant two-photon excitation scheme to study high principal quantum number even-parity (2pnp) Rydberg states of atomic carbon. This scheme uses intense vacuum ultraviolet light to drive the resonance transition of the atoms, followed by excitation to Rydberg states with tunable ultraviolet light. Atomic carbon was produced under high vacuum condit...

Using ab-initio simulations, we demonstrate amplification of XUV radiation in a high-harmonic generation type process in the hydrogen molecular ion. A small fraction of the molecules is pumped with 9 eV photons to a dissociative Rydberg state from which IR-assisted XUV amplification is observed up to 22 eV. We show that starting at IR driving field intensities of 2 × 10 W/cm, the hitherto domin...

Energy level separations in high-lying Rydberg states of neutral aluminium have been measured by a two-photon millimetre-wave resonance method to obtain n 2F–(n + 1) 2F intervals for n = 29–37 with an accuracy ±1 MHz. An Al atomic beam was excited stepwise by pulsed lasers, and the Rydberg atoms were detected by state-selective field ionization. From these data and previous optical data for the...

Rotations about its three carbon-nitrogen bonds give triethylamine a complex, 3-dimensional potential energy landscape of conformeric structures. Electronic excitation to Rydberg states prepares the molecule in a high-energy, nonequilibrium distribution of such conformers, initiating ultrafast transitions between them. Time-resolved Rydberg electron binding energy spectra, observed using photoi...

The accuracy of zero-electron-kinetic-energy ~ZEKE! photoelectron spectroscopy rests on the ultralong lifetimes of the high-n, high-l Rydberg states that are responsible for the ZEKE signal. However, a few-photon process cannot excite electrons directly from the low-l ground state to the high-l ZEKE manifold. In this paper we show that using the dynamics of Rydberg Stark states in slowly time d...