Imaging an isolated water molecule using a single electron wave packet

Observing changes in molecular structure requires atomic-scale Ångstrom and femtosecond spatio-temporal resolution. We use the Fourier transform (FT) variant of laser-induced electron diffraction (LIED), FT-LIED, to directly retrieve the molecular structure of H2O + with picometer and femtosecond resolution without a priori knowledge of the molecular structure nor the use of retrieval algorithms or ab initio calculations. We identify a symmetrically stretched H2O + field-dressed structure that is most likely in the ground electronic state. We subsequently study the nuclear response of an isolated water molecule to an external laser field at four different field strengths.We acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO), through the “Severo Ochoa” Programme for Centres of Excellence in R&D (Grant No. SEV-2015-0522) Fundació Cellex Barcelona and the CERCA Programme/Generalitat de Catalunya. X.L., K.A., T.S., A.S., B.B., M.S., and J.B. acknowledge the European Research Council (ERC) for ERC Advanced Grant TRANSFORMER (Grant No. 788218), MINECO for Plan Nacional Grant No. FIS2017-89536-P, AGAUR for 2017 Grant No. SGR1639, and Laserlab-Europe (EU-H2020 654148). K.A., J.B., and R. Moszynski acknowledge the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314. X.L. and J.B. acknowledge financial support from China Scholarship Council. A.S. and J.B. acknowledge Marie Sklodowska-Curie Grant Agreement No. 641272. J.S. and S.G. acknowledge the ERC Consolidator Grant QUEMCHEM (Grant No. 772676). C.D.L. is supported by the U.S. Department of Energy under Grant No. DE-FG02-86ER13491.Postprint (published version