Femtosecond dynamics of electronic excitations of adsorbates studied by two-photon photoemission pulse correlation: CO/Cu(111)
✍ Scribed by E. Knoesel; T. Hertel; M. Wolf; G. Ertl
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 833 KB
- Volume
- 240
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
An equal pulse correlation technique based on angle-resolved two-photon photoemission is employed to investigate the lifetime of electronic excitations of an adsorbate on a single crystal metal surface. Photoemission from an occupied surface state on Cu(ll1) by a non-resonant two-photon process via the sp-band gap is used to characterize directly at the surface the width and shape of 65 fs laser pulses at a photon energy of hv= 3.4 eV. The 2PPE correlation technique allows the establishment of an upper limit of 7 < 20 fs for the lifetime of the 2 IT ?? resonance of CO adsorbed on C&11), whereas from the spectral width of the 27~ * level a lower limit of = 1 fs is estimated.