• attosecond science;
  • electron localization


Numerical solutions of the time-dependent Schrödinger equation for a 1D model non-Born–Oppenheimer Hmath image are used to illustrate the nonlinear nonperturbative response of molecules to intense (I ≥ 1013 W/cm2), ultrashort (t < 10 fs) laser pulses. Molecular high-order harmonic generation (MHOHG) is shown to be an example of such response and the resulting nonlinear photon emission spectrum is shown to lead to the synthesis of single attosecond (10−18 s) pulses. Application of such ultrashort pulses to the Hmath image system results in localized electron wavepackets whose motion can be detected by asymmetry in the photoelectron spectrum generated by a subsequent probe attosecond pulse, thus leading to measurement of electron motion in molecules on the attosecond time scale. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004