Knowledge Bank

An algorithm is presented for the determination of the effect of hyperfine coupling on rotational energy levels in a molecule containing an arbirary number of coupling nuclei with arbitrary spin. The uncoupled representation in used, and matrix elements are given for the quadrupole, spin-rotation, spin-spin, and Stark interactions. The program can be expanded to include other multipole interactions if necessary. The case of three identical nuclei with spin of 1 is discussed. This program can also be used in choosing states for beam MASER spectroscopy. As an example, results of calculations are presented for two states of acetonitrile to determine which states will focus or defocus for various focussing voltages.