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Photoemission in a nanoscale two-tip junction – accepted in PRB

How do optical near-fields between two ultrasharp metal needles of femtosecond laser pulses couple at the nanometer level? This question is addressed in our recently accepted manuscript, which has been just accepted in PRB. Together with our colleagues from the Chair of Solid State Physics, we developed a scanning tunneling microscope with which we were able to precisely position two nanometer-sized metal needles, so that they form an only few nanometer large gap junction facing each other. The nonlinear photoemission in the gap junction under illumination with femtosecond laser pulses, allows us to draw quantitative conclusions about the field enhancement at the tip apices. We have thus been able to show that nanometer-sharp metal tips are suitable as ultrafast near-field sensors.