Speaker
Description
Heisenberg uncertainty principle does not allow atoms in a molecule to have perfectly well-defined positions. Thus, each measurement of a molecular geometry probes a slightly different structure, even in the ground state. These quantum fluctuations are collective in essence: the atoms do not fluctuate independently relative to each other, but follow concerted patterns, usually described by normal modes. Measuring them in a complex molecule is challenging, as it requires a method that captures structural information from measurements of single molecules.
In this talk, I will present how we achieved it for an 11-atom molecule by inducing its Coulomb explosion at the European XFEL. In the experiment, the momenta of the fragments are measured in coincidence, and I will show that this data carries information about the ground-state fluctuations of the molecular structure despite our measurements detecting only a fraction of the 11 atomic fragments in coincidence. I will describe how we tackled this challenge by developing an analysis method that reconstructs the missing information. We use it to then assign specific features of the measured momenta to specific structural fluctuations of the molecule before its explosion, establishing that Coulomb explosion has the power to probe collective molecular effects in large molecules.