Photoabsorption spectra of a laser produced Sn plasma

M. Lysaght, D. Kilbane, A. Cummings, N. Murphy, P. Dunne, G. O'Sullivan, L. Gaynor, P. Van Kampen, J. T. Costello, E. T. Kennedy

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)


The search for a source of EUV radiation for photolithography in the 13.5 nm region has been narrowed down to laser produced or pulsed discharge plasmas containing either xenon or tin.1 Higher conversion efficiencies can however be obtained with tin based plasmas within this wavelength regime. 2 It is known that EUV photoabsorption by the lower ion stages of xenon reduces the photon flux from a xenon source.3 This is due to shape resonances from 4d → εf transitions within Xe I - IV. The corresponding resonances for Sn I - IV have been obtained by means of the dual laser plasma (DLP) technique.4 It is also found that above the 4d ionisation threshold the spectra of Sn I - IV are dominated by a 4d → εf shape resonance which peaks at close to 65 eV in each case. A transfer of oscillator strength from the shape resonance to pseudo-discrete 4d → nf transitions with increasing ionisation is clearly evident. Hartree Fock with configuration interaction and relativistic time dependent local density approximation calculations successfully account for this behaviour and also permit identification of the discrete features.

Original languageEnglish
Article number33
Pages (from-to)273-280
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2005
Externally publishedYes
EventOpto-Ireland 2005: Optical Sensing and Spectroscopy - Dublin, Ireland
Duration: 04 Apr 200506 Apr 2005


  • EUV
  • Laser produced plasma
  • Photoabsorption


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