@article {PhysRevLett.116.073901,
	title = {Ultrafast Excitation of an Inner-Shell Electron by Laser-Induced Electron Recollision},
	journal = {Phys. Rev. Lett.},
	volume = {116},
	year = {2016},
	month = {Feb},
	pages = {073901},
	publisher = {American Physical Society},
	abstract = {Extreme ultraviolet attosecond pulses, generated by a process known as laser-induced electron recollision, are a key ingredient for attosecond metrology, providing a tool to precisely initiate and probe subfemtosecond dynamics in atoms, molecules, and solids. However, extending attosecond metrology to scrutinize the dynamics of the inner-shell electrons is a challenge, that is because of the lower efficiency in generating the required soft x-ray (ℏω\&gt;300  eV) attosecond bursts. A way around this problem is to use the recolliding electron to directly initiate the desired inner-shell process, instead of using the currently low flux x-ray attosecond sources. Such an excitation process occurs in a subfemtosecond time scale, and may provide the necessary {\textquotedblleft}pump{\textquotedblright} step in a pump-probe experiment. Here we used a few cycle infrared (λ0≈1800  nm) source and observed direct evidence for inner-shell excitations through the laser-induced electron recollision process. It is the first step toward time-resolved core-hole studies in the keV energy range with subfemtosecond time resolution.},
	doi = {10.1103/PhysRevLett.116.073901},
	url = {http://link.aps.org/doi/10.1103/PhysRevLett.116.073901},
	author = {Deng, Yunpei and Zhinan Zeng and Zhengmao Jia and Pavel Komm and Yinhui Zheng and Xiaochun Ge and Ruxin Li and Marcus, Gilad}
}
