RESUMEN
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 H2 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.
RESUMEN
The NO(2) ion pair photodissociation dynamics leading to NO(+)(X(1)Sigma(+),v) + O(-)((2)P(3/2) or (2)P(1/2)), induced by a 1 kHz femtosecond laser with wavelengths near 400 nm, has been characterized using the coincidence vector correlation method. The ion pair production after four-photon absorption reaches more than 15% of the primary ionization. The kinetic energy release of the fragments demonstrates a significant vibrational excitation of the NO(+)(X(1)Sigma(+),v) molecular fragment. Recoil ion fragment emission is strongly aligned along the polarization axis of linearly polarized light or preferentially emitted in the plane perpendicular to the propagation axis of circularly polarized light. The formalism describing the recoil anisotropy for bound-to-bound n-photon transition inducing prompt axial recoil dissociation of a nonlinear molecule has been developed to interpret the measured anisotropies in terms of excitation pathways via near-resonant intermediate states of specific symmetries. Possible reaction pathways are discussed that are consistent with the data and supported by calculations of potential energy surfaces and transition moments.