Frankfurt 2006 – scientific programme

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Q: Quantenoptik und Photonik

Q 43: Anwendung ultrakurzer Lichtimpulse und Attosekundphysik

Q 43.5: Talk

Wednesday, March 15, 2006, 12:10–12:25, HIV

Femtosecond electron pulses from ultrasharp field emitters — •Peter Hommelhoff, Catherine Kealhofer, and Mark Kasevich — Physics Department, Stanford University, Stanford, California, USA

We focus sub-8fs nanojoule laser pulses with a repetition rate of 150 MHz onto ultrasharp field emitters. The electric field at the tip reaches GV/m, enabling optical field emission (modulation of the tunnel barrier). At low power we observe photofield emission (excitation of electron and subsequent tunnenling). Both processes are prompt. Electrons are emitted from a nanometer sized region on the tip apex into an electron beam with an opening angle of the order of 10^∘, enabling for a high brightness femtosecond electron source. We use the tip as a non-linear detector to measure interferometric laser pulse autocorrelation traces right in the photoelectron current. The non-linearity is tunable via the DC voltage applied to the tip and reaches peak-to-baseline ratios of more than 20 (this ratio is 8 for a doubling crystal autocorrelator). We discuss advanced emitters such as single-atom tips and carbon nanotubes and applications of these emitters as novel electron sources and sensors.