HYPERFINE QUANTUM BEATS IN C2N2

Molecular quantum beats are observed in the isotropic fluorescence dec ay following laser excitation of individual rotational states of C2N2 via the vibronically allowed 4(0)1 A(1SIGMA(U)-)<--X(1SIGMA(g)+) trans ition near 219 nm. Strong quantum beats occur with selective excitatio n, by both P- and R-branch transitions, of over a dozen rotational sta tes. Observations of hyperfine quantum beats following excitation of t he N' = 12 rotational level yield estimates of spin-orbit coupling mat rix elements, Born-Oppenheimer state separations, and magnetic and qua drupolar hyperfine coupling constants. Observations of Zeeman splittin g establish that the three hyperfine levels of N' = 12 are coupled to those of a single triplet state.