Laser-assisted-autoionization dynamics of helium resonances with single attosecond pulses
نویسندگان
چکیده
The strong coupling between two autoionizing states in helium is studied theoretically with the pump-probe scheme. An isolated 100-as XUV pulse is used to excite helium near the 2s2p(1 P ) resonance state in the presence of an intense infrared (IR) laser. The laser field introduces strong coupling between 2s2p(1 P ) and 2p2(1 S) states. The IR also can ionize helium from both autoionizing states. By changing the time delay between the XUV and the IR pulses, we investigated the photoelectron spectra near the two resonances. The results are used to explain the recent experiment by Gilbertson et al. [Phys. Rev. Lett. 105, 263003 (2010)]. Using the same isolated attosecond pulse and a 540-nm laser, we also investigate the strong coupling between 2s2p(1 P ) and 2s2(1 S) by examining how the photoelectron spectra are modified versus the time delay and the possibility of observing Autler-Townes doublet in such experiments.
منابع مشابه
Probing and controlling autoionization dynamics of atoms with attosecond light pulses
The time evolution of an autoionizing atomic system is studied theoretically in the presence of a moderately intense dressing laser pulse. We first examine how an autoionizing wave packet evolves in time in the absence of an external field, and take the single 2pns(1P) resonances in beryllium as examples. Alternatively, we study the electron dynamics where an attosecond extreme ultraviolet (XUV...
متن کاملTheory of laser-assisted autoionization by attosecond light pulses
We present a quantum theory of the decay of an autoionizing state created in the attosecond xuv sextreme ultravioletd pump and laser probe measurements within the strong field approximation employing resonance parameters from Fano’s theory. From the electron spectra versus the pump-probe time delay, we show how the lifetimes of the resonances can be extracted directly from the time domain measu...
متن کاملAttosecond-resolved evolution of a laser-dressed helium atom: interfering excitation paths and quantum phases.
Using high-order harmonic attosecond pulse trains, we investigate the photoionization dynamics and transient electronic structure of a helium atom in the presence of moderately strong (∼10(12) W cm(-2)) femtosecond laser pulses. We observe quantum interferences between photoexcitation paths from the ground state to different laser-dressed Floquet state components. As the intensity ramps on fem...
متن کاملResonant enhancement of a single attosecond pulse in a gas medium by a time-delayed control field
An optical coherent control scheme has been proposed and theoretically investigated where an extreme ultraviolet single attosecond pulse (SAP) propagates through dense helium gas dressed by a time-delayed femtosecond laser pulse. The laser pulse couples the 2s2p(1P) and 2s2(1S) autoionizing states when the SAP excites the 2s2p state. After going through the gas, the spectral and temporal profil...
متن کاملGeneration and Characterization of Sub-70 Isolated Attosecond Pulses
Dynamics occurring on microscopic scales, such as electronic motion inside atoms and molecules, are governed by quantum mechanics. However, the Schrödinger equation is usually too complicated to solve analytically for systems other than the hydrogen atom. Even for some simple atoms such as helium, it still takes months to do a full numerical analysis. Therefore, practical problems are often sol...
متن کامل