title: Scaling Laws of the Two-Electron Sum-Energy Spectrum in Strong-Field Double Ionization.
abstract: The sum-energy spectrum of two correlated electrons emitted in nonsequential strong-field double ionization (SFDI) of Ar was studied for intensities of 0.3 to 2×10^{14} W/cm^{2}. We find the mean sum energy, the maximum of the distributions as well as the high-energy tail of the scaled (to the ponderomotive energy) spectra increase with decreasing intensity below the recollision threshold (BRT). At higher intensities the spectra collapse into a single distribution. This behavior can be well explained within a semiclassical model providing clear evidence of the importance of multiple recollisions in the BRT regime. Here, ultrafast thermalization between both electrons is found occurring within three optical cycles only and leaving its clear footprint in the sum-energy spectra.
authors.affiliation: Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China.
authors.forename: Difa
authors.initials: D
authors.lastname: Ye
authors.affiliation: Department of Physics and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, People's Republic of China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China.|CAPT, HEDPS, and IFSA Collaborative Innovation Center of MoE, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Libin
authors.initials: L
authors.lastname: Fu
authors.affiliation: Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China.|CAPT, HEDPS, and IFSA Collaborative Innovation Center of MoE, Peking University, Beijing 100871, People's Republic of China.|Center for Fusion Energy Science and Technology, China Academy of Engineering Physics, Beijing 100088, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Physics and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, People's Republic of China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Qihuang
authors.initials: Q
authors.lastname: Gong
authors.affiliation: Department of Physics and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, People's Republic of China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China.
authors.forename: Yunquan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.|Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ullrich