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O: Oberflächenphysik
O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)
O 28.60: Poster
Mittwoch, 10. März 2004, 16:00–19:00, Bereich C
State selective detection of D2 after femtosecond-laser induced desorption from Ru(001) — •S. Wagner1, M. Rutkowski2, R. Dudek3, C. Frischkorn1, H. Zacharias2, and M. Wolf1 — 1Freie Universtät, Berlin — 2Westfälische Wilhems-Universität, Münster — 3Fritz–Haber–Institut der MPG, Berlin
The energy transfer into different degrees of freedom in the fs-laser induced recombinative desorption of deuterium from Ru(001) has been investigated with (1+1’)-REMPI and time-of-flight measurements. It has been shown that hot substrate electrons mediate this reaction within a few hundred femtoseconds [1]. The rovibrational distributions of the desorbing D2 molecules are detected via various B 1 Σu+ ← X 1 Σg+ Lyman bands using tunable vacuum ultraviolet (VUV) laser radiation for the resonant excitation step [2]. Populations of the rotational quantum states in the vibrational ground and the first excited state are measured. The rotational energy of D2 in the vibrational ground state (Erot /kB=800±200 K) is much lower than the rotational energy in the excited state (Erot /kB=1500±300 K). Assuming a Boltzmann-like energy distribution, these results indicate a vibrational temperature of Evib /kB=1200±150 K. The amount of energy coupled to the translation is Etrans/kB=1700±300 K. Possible reasons for the incomplete thermalization will be discussed.
[1] D. N. Denzler, C. Frischkorn, C. Hess, M. Wolf, and G. Ertl, Phys. Rev. Lett., in press
[2] D. Wetzig, M. Rutkowski, H. Zacharias, and A. Groß; Phys. Rev. B 63, 205412 (2001)