26 April 2019
Vol 364, Issue 6438

About The Cover

Cover image expansion

COVER Chemists have long sought to understand the atomic-scale motion and energy dissipation pathways associated with covalent bond formation. When a hydrogen atom (white) collides with graphene (black), a transient carbon-hydrogen bond may form. As a result of rehybridization, repulsion of neighboring carbon atoms leads to rapid energy transfer through sonic waves (white rings), which stabilize the bond. See pages 331 and 379. Illustration: V. Altounian/Science