Electron Density Map of PS II (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption This electron density map of the manganese-calcium cluster in the photosystem II complex showed that the cluster was not dislocated by the LCLS X-ray beams before image data was acquired, proof that the probe before destroy approach is feasible for this system at the LCLS. Credit Image courtesy of Berkeley Lab Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.