05 June 2020
Vol 368, Issue 6495

About The Cover

Cover image expansion

COVER Artistic abstraction of how ammonia solutions change with increasing excess electron concentration. Microjets of liquid ammonia can be used to track how an electrically insulating liquid becomes a metal, with an accompanying color change from transparent blue through deeper blue to bronze. Mapping energy levels spectroscopically and theoretically reveals a gradual transition from electrolyte to liquid metal. See pages 1056 and 1086.
Illustration: C. Bickel/Science