Surface-plasmon–assisted electron pair formation in strong electromagnetic field
1 Wigner Research Centre for Physics - Konkoly-Thege M. út 29-33, 1121 Budapest, Hungary
2 ELI-HU Nonprofit Kft. - Dugonics Tér 13, 6720 Szeged, Hungary
Received: 27 November 2013
Accepted: 8 March 2014
In this work the strong electromagnetic field of femtosecond Ti:Sa lasers was used to excite surface plasmon oscillations (SPOs) in gold films at room temperature in the Kretschmann geometry. Experimental investigations were carried out using a surface plasmon near field scanning tunneling microscope, measuring its response to excitation at SPO hot spots on the gold surface. Furthermore, the spectra of photoelectrons, liberated by multiplasmon absorption, have also been measured by a time-of-flight spectrometer. In both cases new type of anomalies in both the STM and electron TOF signals have been measured in the same laser intensity range. The existence of these anomalies may be qualitatively understood, by using the intensity-dependent expression for the effective electron-electron scattering potential, derived earlier in a different context. In this theoretical work an effective attraction potential has been predicted in the presence of strong inhomogeneous radiation fields.
PACS: 71.45.Gm – Exchange, correlation, dielectric and magnetic response functions, plasmons / 79.60.-i – Photoemission and photoelectron spectra / 68.37.Ef – Scanning tunneling microscopy (including chemistry induced with STM)
© EPLA, 2014