Multiphoton-induced X-ray emission at 4-5 keV from Xe atoms with multiple core vacancies

• Published in: Nature (London) 1994-08, Vol.370 (6491), p.631-634
• Main Authors: McPherson, A, Thompson, B. D, Borisov, A. B, Boyer, K, Rhodes, C. K
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; Atomic spectra; Atoms & subatomic particles; Exact sciences and technology; Humanities and Social Sciences; letter; multidisciplinary; Multiphoton ionization and excitation to highly excited states (e.g., rydberg states); Multiphoton ionization and excitation to highly excited states (eg, Rydberg states); Photon interactions with atoms; Physics; Science; Science (multidisciplinary); X-ray spectra; X-rays; Xenon
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/370631a0

SEVERAL recent experimental findings 1–3 have pointed to a possible route for making an X-ray laser, which could in principle provide an imaging system capable of molecular resolution 4 . The method involves the multiphoton excitation of atoms in van der Waals clusters or in molecules to yield ions with core-electron vacancies 1,2 , which can then decay by emission of X-rays, in conjunction with a self-chanelling propagation mode of electromagnetic radiation 3 . The multiphoton excitation may be stimulated by ultrahigh-brightness, subpicosecond pulses of laser light 5 . We have previously observed 2 emission of X-rays from L-shell transitions in core-excited krypton atoms using this approach. Here we report the multiphoton production of X-rays of wavelength 2–3 Å from highly ionized xenon atoms which possess a large number of innershell vacancies while retaining several electrons in relatively weakly bound outer orbitals. Atoms with this ‘inverted’ electronic configuration are designated ‘hollow atoms’ 6,7 . We find that generation of hollow atoms can become the dominant excitation mode for such systems, making their exploitation in an X-ray laser a real possibility.