State‐specific collision dynamics of OH radicals and N atoms

Open shell species, with a variety of spectroscopically accessible quantum states, offer opportunities for laser generation of nonequilibrium spatial distributions in both the laboratory (mJ) and molecular (Λ‐doublet) frames. In addition, laser excitation can also select the relative orientation of the spin and orbital angular momentum in these systems. The quantum state distributions can be interrogated by a delayed second laser pulse or by resolving the polarization and/or wavelength of the resulting fluorescence. In experiments on the OH radical, we have observed propensities for retention of electronic parity and spatial orientation during rotationally inelastic collisions of, respectively, the X 2Πi and A 2Σ+ electronic states. In nitrogen atoms, we have qualitatively determined the magnitude of fine structure, mJ and electronic state changing collisions in the 2s22p23p 4D0 electronic state.