Odd Rydberg spectrum of20NeI: High resolution laser spectroscopy and multichannel quantum defect theory analysis

Measurement of Photoionization Cross-Section for the Excited States of Atoms: A Review

A review of experimental studies of the measurement of the photoionization cross-section for the excited states of the alkali atoms, alkaline earth atoms, and rare-gas atoms is presented, with emphasis on using multi-step laser excitation, ionization, and the saturation technique. The dependence of the photoionization cross-section from different intermediate states populated in the first step and ionized in the second step are discussed, including results on the photoionization cross-sections measured above the first ionization threshold. Results based on different polarizations of the exciting and the ionizing dye lasers are also discussed. Examples are provided, illustrating the photoionization cross-sections measured using thermionic diode ion detector, atomic beam apparatus in conjunction with a time-of-flight mass spectrometer and DC/RF glow discharge cell as an optogalvanic detection.

Observation of resonant interatomic coulombic decay in Ne clusters

We have measured the electron spectra of Ne clusters after excitation with photon energies around the 2s inner valence threshold. At two photon energies below threshold, a resonantly enhanced surplus of low kinetic-energy electrons is observed. The kinetic energy of the peak does not vary with the photon energy and is slightly larger than the transition energy of Interatomic Coulombic Decay (ICD) above threshold. This leads us to assume that an ICD-like process is present. In analogy to the Auger and the resonant Auger decay this new phenomenon is termed resonant ICD.

Experimental evidence for interatomic coulombic decay in Ne clusters

Electron spectra of photoexcited Ne clusters are shown to display a signal at low kinetic energies that is neither present in the Ne monomer nor at photon energies below the inner-valence 2s threshold. These findings are strong evidence for the existence of interatomic Coulombic decays (ICD), a mechanism that was recently predicted theoretically [Phys. Rev. Lett. 79, 4778 (1997)]]. In ICD, an inner-valence hole state in a weakly bonded system can undergo ultrafast relaxation due to energy transfer to a neighboring atom, followed by electron emission from this neighboring site.

Optical determination of the (20,22)Ne 3s-3p specific mass shift

By using a supersonic beam of metastable Ne* atoms and a single-mode dye laser we determine the 2p(5)3s-3p specific mass shift of the (20,22)Ne isotopes by means of optical spectroscopy. The resulting value, on the basis of a systematic measurement of transition isotope shifts at different transition energies between 15,300 and 17,000 cm(-1), is 473 +/- 2.5 MHz. This is ~ 50 MHz larger than the best-known theoretical value.