Circular dichroism in photoionization of oriented nonlinear molecules

Abstract

It is shown that the angular distribution of $E1\mathrm{}$ photoelectrons from oriented nonlinear molecules exhibits circular dichroism. The study, based upon a general expression that is obtained by taking full account of the transformation properties of the point-symmetry group of the target, reveals that, unlike the case of fixed linear molecules, (i) it may arise even if there is only a single photoelectron continuum, (ii) all terms, interference or otherwise, in $-L\le M(=m-m^{\prime })\le L$ with $L$ both even and odd contribute, and (iii) there are in general no restrictions on the experimental arrangement for it to be observable in nonlinear systems. This discussion has been illustrated by ionization in the $6a_1$ orbital in an oriented C${\mathrm{Cl}}_4$ molecule.