Circular dichroism in the angular distribution

It may be worthwhile to compare briefly the PECD phenomenon discussed here, which relates to randomly oriented chiral molecular targets, with the likely more familiar Circular Dichroism in the Angular Distribution (CDAD) that is observed with oriented, achiral species [44 7]. Both approaches measure a photoemission circular dichroism brought about by an asymmetry in the lab frame electron angular distribution. Both phenomena arise in the electric dipole approximation and so create exceptionally large asymmetries, but these similarities are perhaps a little superficial. 

CP) Qjj-Quiaj-iy polarized radiation. The intensity difference means that a Circular Dichroism in the Angular Distribution of photoelectrons (CDAD) effect is present. 

MCDAD Magnetic circular dichroism in the angular distribution of photoelectrons... 

Magnetic circular and Unear dichroism in the angular distribution of photoelectrons (MCDAD and MLDAD) are due to the interaction between spin-orbit coupling and exchange splitting. Thus, the intensity distribution of the emitted photoelectrons becomes modified as a ftmction of the macroscopic magnetization direction and the photon spin. The magnetic dichroism is an effect which requires a chirality of the system. 

The investigation of chiral molecular phenomena, and associated technique development, thus hnds potentially signihcant practical applications to place alongside the fundamental interest of this topic. This chapter will examine the recently investigated phenomenon of photoelectron circular dichroism (PECD) that arises from a dissymmetry in the angular distribution of photoelectrons... 

Molecular alignment (see Section 8.11.2) can be probed by measurement of the circular dichroism in the photoelectron angular distribution (CDAD). CDAD spectra are obtained by taking the difference between angle-resolved photoelectron spectra for left and right circularly polarized light (Dubs, et al., 1986). 

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