Knowledge Bank

A three-dimensional are coordinate $system1$ is used to treat the electronic motion along a thick, instead of infinitely thin, helix. Extending the existing work on ``one-dimensional’’ longitudinal motion along an infinitely thin helix, we have computed electronic dipole and magnetic dipole matrix elements involving transverse quantum numbers and covering integral as well non-integral number of helical turns. The contribution of these transverse motions to optical and magneto-optical effects will be discussed. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$E. A. Power and T. Thirunamachandran, Proc. Roy. Soc. London A313 403 (1969). Chiu, Ying-Nan