2015, Tanyag, Rico Mayro P., Bernando, Charles, Jones, Curtis F., Bacellar, Camila, Ferguson, Ken R., Anielski, Denis, Boll, Rebecca, Carron, Sebastian, Cryan, James P., Englert, Lars, Epp, Sascha W., Erk, Benjamin, Foucar, Lutz, Gomez, Luis F., Hartmann, Robert, Neumark, Daniel M., Rolles, Daniel, Rudek, Benedikt, Rudenko, Artem, Siefermann, Katrin R., Ullrich, Joachim, Weise, Fabian, Bostedt, Christoph, Gessner, Oliver, Vilesov, Andrey F.

Lensless x-ray microscopy requires the recovery of the phase of the radiation scattered from a specimen. Here, we demonstrate a de novo phase retrieval technique by encapsulating an object in a superfluid helium nanodroplet, which provides both a physical support and an approximate scattering phase for the iterative image reconstruction. The technique is robust, fast-converging, and yields the complex density of the immersed object. Images of xenon clusters embedded in superfluid helium droplets reveal transient configurations of quantum vortices in this fragile system.