The PhotoElectron Angular Distribution
Less widely recognised, is that this equation is just a special (though common) sub-case of the more general expression:
But, for the specific case of a chiral molecule ionized with CPL, these P1 (1st Legendre Polynomial) coefficients are found to be antisymmetric for exchange of handedness of either the molecular enantiomer or the light polarization: b1+1 = − b1−1 .
Asymmetry in the PAD
Lab Frame PADs
A lab-frame PAD represents an average taken over all possible initial molecular orientations. There is a consequent loss of dynamical information, although experimentally it is a less challenging measurement to make. For a one-photon ionization with linearly polarized light the PAD has a well known form†:
† but as our PECD work now shows an additional term is needed for circular polarizations.