Professor Wen Li's research interests lie in developing and applying novel probes to study reaction dynamics at their most detailed level. The goal of our research is to understand, predict and eventually control a chemical reaction in the most effective way. The probes include strong field ionization and ultrashort electron and photon pulses produced from high order harmonic generation (HHG). HHG itself is also a strong field process that can be described semi-classically using a 3-step model: 1. ionization of a bound electron from an atom by a strong laser field; 2. propagation and acceleration of the electron in the laser field; 3. recombination of the electron with the ion core to emit high energy photons. Both the 'recombining' electron and the emitted photon can be used to probe chemical dynamics. Due to the intrinsic ultrafast property of HHG, the pulse duration of the photon and electron can be as short as a few tens of attoseconds (10-18s). These fast pulses enable us for the first time to directly probe the attosecond dynamics of the electrons, which play a dominant role in reactions relevant to physics, chemistry and biology.