6533b7d1fe1ef96bd125cbde
RESEARCH PRODUCT
Multiphoton photoemission electron microscopy using femtosecond laser radiation
Yeukuang HwuGerhard H. FecherGerhard H. FecherGerd SchönhenseOliver G. Schmidtsubject
RadiationMaterials scienceInverse photoemission spectroscopyPhysics::OpticsAngle-resolved photoemission spectroscopyPhoton energyPhotoelectric effectCondensed Matter PhysicsLaserAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic Materialslaw.inventionPhotoemission electron microscopylawSecondary emissionFemtosecondPhysical and Theoretical ChemistryAtomic physicsSpectroscopydescription
Abstract The interaction of intense, pulsed laser radiation with surfaces results in non-linear optical effects that are responsible for emission of electrons even if the photon energies are below the work function. In the present study, photoelectrons have been excited by means of femtosecond laser pulses from a frequency doubled Ti:sapphire laser with a photon energy of 3.1 eV. The spatial distribution of the photo emitted electrons was imaged using a photoemission electron microscope. All samples exhibit centres of enhanced second or higher order photoemission yield, so called ‘hot spots’. These ‘hot spots’ were preferentially excited with s-polarised light. This behaviour may be explained on the basis of a microscopic model assuming localised plasmon excitations in small particles. Lead films and pentacene layers adsorbed on silicon have been studied. The photoelectron yield depends strongly on the sample topography and the polarisation of the photons. The polarisation and power dependence of the multi-photon photoemission yield were studied. Clear evidence for three-photon contributions has been found although two-photon photoemission is sufficient to overcome the surface barrier.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2002-10-01 | Journal of Electron Spectroscopy and Related Phenomena |