Circular dichroism is a consequence of chirality. However, nonchiral molecules can also exhibit it when the measurement itself introduces chirality, e.g., when measuring molecular-frame photoelectron angular distributions. The few such experiments performed on homonuclear diatomic molecules show that, as expected, circular dichroism vanishes when the molecular-frame photoelectron angular distributions are integrated over the polar electron emission angle. Here we show that this is not the case in resonant dissociative ionization of ${\mathrm{H}}_2$ for photons of 30–35 eV, which is the consequence of the delayed ionization from molecular doubly excited states into ionic states of different inversion symmetry.

• Received 23 March 2010

DOI:https://doi.org/10.1103/PhysRevLett.104.233003