Dresden 2003 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Oberflächenphysik
O 12: Postersitzung (Struktur und Dynamik reiner Oberfl
ächen, Grenzfl
äche fest-flüssig, Nanostrukturen, Teilchen und Cluster, Halbleiteroberfl
ächen und Grenzfl
ächen, Zeitaufgelöste Spektroskopie, Rastersondentechniken, Methodisches)
O 12.37: Poster
Montag, 24. März 2003, 18:00–21:00, P1
Laser assisted field emission from tungsten field emitter tips — •Sven Schramm, Johannes Schneider, and Walter Pfeiffer — Physikalisches Institut, Uni Würzburg, Am Hubland
Field emission from metal surfaces occurs at a field strengths of more than 109 V/m. Electrons in states close to the Fermi-energy then tunnel through the barrier and give rise to the field emission current. The high field strength is usually achieved at the tip apex of sharp metal tips. Focussing of ultrashort (50 fs) and intense laser pulses (100 nJ) on the tip apex generates a maximum laser field strength of the same order of magnitude. Therefore the illumination leads to a substantial perturbation of the potential barrier, giving rise to photo-assisted tunnelling. Time- and energy-resolved photo-field emission experiments at tungsten tips indicate that the emission of photo-excited electrons is indeed influenced by the strong field.