The first evidence of highly charged ion production from intense laser–cluster interactions was the observation of ‘‘anomalous’’ X-ray emission lines corresponding to highly stripped ions [4]. Strong M- and L-shell emission was observed from Kr and Xe clusters targets, including a component attributed to Kr9+. Shortly afterwards, high charge states of I and Ar ions were seen from small HI and HIArn clusters exposed to intense, femtosecond pulses [45]. For these small clusters a Coulomb explosion model could explain the ion energies that were a few hundred eV. This was followed by the observation at Imperial College of keV electrons emitted from large Xe clusters irradiated by femtosecond pulses of intensity ~1016 W cm-2, suggestive of a solid target laser–plasma interaction [43]. In the same issue of Physical Review Letters, observation of very highly charged ions from Xe and Kr clusters was reported [46] – using femtosecond pulses at an intensity in the vicinity of 1015 W cm-2 , Xe20+ and Xe18+ were seen in ion time-of-flight (TOF) spectra. Even higher charge states (up to Xe40+) were then seen by the Imperial College physicists, who also observed average ion energies of ~45 keV with a maximum extending to 1 MeV in the interaction of femtosecond laser pulses (again ~1016 W cm-2) with several thousand atom rare-gas clusters [47,48]. The transition from molecular to plasma behaviour was now manifest. These first direct measurements of high energy, highly charged ions were later confirmed and extended by other groups [44,49]. In the following sections we summarise the ion emission data obtained at Imperial College. Ahead of this, a short description of the Imperial College laser system and interaction chamber is given. (underline added, see Dissociation)
See Also
3.14 - Vortex Theory of Atomic Motions 3.23 - Hydrodynamic Equations - Vortex Motions 5.8.5 - The complete Contraction Expansion Cycle is as follows 9.27 - Expansion and Contraction 13.04 - Atomic Subdivision 16.15 - Negative Electricity is Expansion atomic Atomic Cluster Heating Atomic Cluster Ionization Atomic Cluster X-Ray Emission Atomic Clusters Atomic Force atomic mass atomic number atomic theory atomic triplet atomic weight diatomic Egyptian fraction expansion expansion Figure 13.06 - Atomic Subdivision Figure 14.10 - Proportionate Tonal Relations dictate Contraction or Expansion Figure 3.28 - Compression and Expansion Forces in Gyroscopic Motions Figure 9.10 - Phases of a Wave as series of Expansions and Contractions Figure 9.5 - Phases of a Wave as series of Expansions and Contractions Force-Atomic Formation of Atomic Clusters Hydrodynamic Expansion InterAtomic Laser Cluster Interactions Law of Atomic Dissociation Law of Atomic Pitch Law of Oscillating Atomic Substances Law of Pitch of Atomic Oscillation Law of Variation of Atomic Oscillation by Electricity Law of Variation of Atomic Oscillation by Sono-thermism Law of Variation of Atomic Oscillation by Temperature Law of Variation of Atomic Pitch by Electricity and Magnetism Law of Variation of Atomic Pitch by Rad-energy Law of Variation of Atomic Pitch by Temperature Law of Variation of Pitch of Atomic Oscillation by Pressure Models of Laser Cluster Interactions monatomic Nanoplasma subatomic