Coherent XUV generation driven by sharp metal tips photoemission Marcelo Ciappina, Jose Antonio Pérez-Hernández, Tahir Shaaran and Maciej Lewenstein Eur. Phys. J. D, 68 6 (2014) 172 Published online: 27 June 2014 DOI: 10.1140/epjd/e2014-50060-4