Time-resolved measurement of vibrational wave-packet dynamics of H<inf>2</inf><sup>+</sup> using multicolor probe pulses

Abstract

Real-time measurement of ultrafast wave-packet dynamics has been possible with advances in short pulse laser technology. The vibrational wave-packet motion of molecular hydrogen ions, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> or D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> , is one of the simple models investigated experimentally using ultrashort laser pulses, a few-cycle Ti: sapphire laser pulse [1], high harmonic generation pulse [2,3], and extreme ultraviolet (XUV) free-electron laser pulse [4]. To measure the vibrational wave-packet dynamics of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> the durations of both pump and probe pulses should be shorter than its vibrational period. We have demonstrated that sub-10 fs high harmonic pulses generated from a sub-15 fs Ti:sapphire laser pulse can be utilized to observe time evolution of the vibrational motion of D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> [3]. In this paper, we report on the time-resolved and vibrational-mode-resolved measurement of the wave-packet dynamics of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> using ultrashort pump and probe pulses, which are generated via high-harmonic generation (HHG) scheme.