How to make a molecular movie
Since the pioneering experiments of Ahmed Zewail and coworkers that started the fascinating field of femtochemisty, it has been a longstanding dream to be able to watch the making and breaking of chemical bonds in real time. Recording such a "molecular movie" requires both atomic scale spatial and femtosecond temporal resolution. Recent advances in the creation of (sub-) femtosecond pulses with optical lasers and X-ray free-electron lasers, coupled with sophisticated experimental techniques such as coincident electron and ion momentum imaging, have now made such molecular movies a reality. I will report on a series of experiments performed at Kansas State University as well as at large-scale free-electron laser facilities aimed at visualizing nuclear and electronic dynamics during photochemical reaction. These experiments open up an exciting new field at the borderline between atomic & molecular physics and physical chemistry which promises to have a profound impact on our understanding and the possible control of chemical reaction dynamics in gas-phase molecules.