ROTATIONALLY STATE-SELECTED AND ORIENTED MOLECULES - PHOTOELECTRON-SPECTROSCOPY AND CHIRALITY OF C-3V MOLECULES

This paper reports a theoretical study of photoionization in a gaseous C-3v molecule prepared in a single \JKM] rotational state of its grou nd electronic motion by an electrostatic hexapole field and oriented i n space by the subsequent application of a weak homogeneous electric f ield E. Markedly different cross-sections are calculated for electrons ejected from 13a(1)(2) orbital of a CH3I molecule by electromagnetic radiation plane polarized parallel and perpendicular to E. These photo currents change further in different manners with rotational states of CH3I. In accord with the experimental observation by Kaesdorf et al. [Phys. Rev. Lett. 54, 885 (1985)], we also find a pronounced asymmetry in the photocurrents emitted in directions along and opposite to E. T his forward - backward asymmetry, which very strongly depends upon the rotational state \JKM] of the molecule, is however more pronounced in parallel than in perpendicular experimental geometry. Both circular a s well as linear dichroisms have also been studied,but neither of thes e shows any forward-backward asymmetry in the present application.