TY - JOUR
T1 - Attosecond-resolved evolution of a laser-dressed helium atom
T2 - Interfering excitation paths and quantum phases
AU - Shivaram, Niranjan
AU - Timmers, Henry
AU - Tong, Xiao Min
AU - Sandhu, Arvinder
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/5/9
Y1 - 2012/5/9
N2 - 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 (∼1012Wcm -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 femtosecond time scales, we observe switching between ionization channels mediated by different atomic resonances. Using precision measurements of ion yields and photoelectron distributions, the quantum phase difference between interfering paths is extracted for each ionization channel and compared with simulations. Our results elucidate photoionization mechanisms in strong fields and open the doors for photoabsorption or photoionization control schemes.
AB - 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 (∼1012Wcm -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 femtosecond time scales, we observe switching between ionization channels mediated by different atomic resonances. Using precision measurements of ion yields and photoelectron distributions, the quantum phase difference between interfering paths is extracted for each ionization channel and compared with simulations. Our results elucidate photoionization mechanisms in strong fields and open the doors for photoabsorption or photoionization control schemes.
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U2 - 10.1103/PhysRevLett.108.193002
DO - 10.1103/PhysRevLett.108.193002
M3 - Article
AN - SCOPUS:84861085233
VL - 108
JO - Physical Review Letters
JF - Physical Review Letters
SN - 0031-9007
IS - 19
M1 - 193002
ER -