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

Abstract

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.