Characteristic spectrum of very low-energy photoelectron from above-threshold ionization in the tunneling regime

Phys Rev Lett. 2012 Jul 27;109(4):043001. doi: 10.1103/PhysRevLett.109.043001. Epub 2012 Jul 23.

Abstract

We report an experimental and theoretical study of very low-energy photoelectrons in tunneling ionization process from noble gas atoms interacting with ultrashort intense infrared laser pulses. A universal peak structure with electron energy well below 1 eV in the photoelectron spectrum, corresponding to the double-hump structure in the longitudinal momentum distribution, is identified experimentally for all atomic species. Our quantum and semiclassical analysis reveal the role of long-range Coulomb potential in the production of this very low-energy peak structure.