Radiative lifetime and quenching of the 3p 4D state of atomic nitrogen

The radiative lifetime of nitrogen atoms in the 3p 4D0 state is determined to be 43±3 ns, and the total removal rate constants from the excited 3p 4D0 state of nitrogen atoms are measured for collisions with He, Ne, Ar, Kr, Xe, and N2. In a low pressure discharge flow reactor, the 3p 4D0 state is prepared by two-photon excitation from the 4S0 ground state of atomic nitrogen. Time-resolved fluorescence from the 3p 4D0→3s 4P transition monitors the temporal evolution of the population in the 3p 4D0 state. As the rare gases become heavier with a more complex electron cloud, the quenching rate constants increase from less than 0.6×10−11 cm3 s−1 for He to a value of 66±12×10−11 cm3 s−1 for Xe. Collision mechanisms which might account for such a dramatic increase are discussed.