Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 65: Nano-Optics IV

Q 65.2: Vortrag

Freitag, 27. März 2015, 11:15–11:30, C/HSO

Field Emission from Metal Nanotips with Terahertz Radiation — •Georg Herink, Lara Wimmer, and Claus Ropers — IV. Physical Institute, University of Göttingen, 37077 Göttingen, Germany

Traditionally, Terahertz (THz) radiation is regarded as being non-ionizing. However, recent advances in table-top THz generation schemes and the field enhancement at metallic nanostructures, provide for local electric fields that are sufficiently high to induce tunneling, e.g., in scanning tunneling microscopy [1]. Here, we experimentally demonstrate THz-induced field emission into the vacuum from the apex of single metallic nanotips [2]. We observe electron kinetic energy distributions which are a result of the sub-cycle emission and acceleration of electrons at the peak of the single-cycle transient [3]. Using a recently introduced THz near-field streaking technique [4], we temporally resolve the enhanced near-field at the nanostructure and map the onset of field emission for increasing THz field strengths. In addition, we utilize the ultrafast emission process to study hot electron relaxation in nanotips. In a pump-probe experiment, we generate hot electrons via femtosecond pulses at 800nm wavelength and resolve ultrafast hot electron dynamics within the apex via THz-induced field emission.

[1] M. Eisele, T. L. Cocker, M. A. Huber, et al., Nature Photonics 8, 620-625 (2013). [2] G. Herink, L. Wimmer, C. Ropers, New Journal of Physics, accepted for publication (2014). [3] G. Herink, D. R. Solli, M. Gulde, C. Ropers, Nature 483, 190-193 (2012). [4] L. Wimmer, G. Herink, D. R. Solli, et al., Nature Physics 10, 432-436 (2014).