Time-resolved Photo-electron Spectroscopy
This method is very similar to Ultra-fast transient absorption, the difference being that the second laser pulse ionizes the molecule. The kinetic energy of the electrons from this process are then detected, through various methods including energy mapping, time of flight measurements etc. As above, the process is repeated many times, with different time delays between the probe pulse and the pump pulse. This builds up a picture of how the molecule relaxes over time. A variation of this method looks at the positive ions created in this process, and is called time-resolved photo-ion spectroscopy (TRPIS)
Read more about this topic: Ultrafast Laser Spectroscopy