ORIENTATIONAL AVERAGING OF LIGHT-SCATTERING OBSERVABLES IN THE T-MATRIX APPROACH

The formalism of the quantum theory of angular momentum is used for orientational averaging of the J matrix, the Hermitian tensor J+J, and the direct product T(nu-nu')* T(mu-mu'). These results are independent of the nature of waves and scatterers. Equations for [J] and [J+J] are interpreted as specific forms of the generalized Wigner-Eckart theorem for the matrix elements of operators J and J+J, which are calculated in terms of symmetrical top eigenfunctions. The averaged values of the above three types of tensor are used for the analytical calculation of a complete set of incoherent light-scattering observables, i.e., the total scattering and extinction cross sections and the Mueller matrix elements.