High Rydberg states and ionization potential of carbon

Abstract

The ionization potential (IP) as well as the coupling and interactions occurring between the states converging to each of the spin-orbit split states of the ground state of the ion core are analyzed using resonance enhanced multiphoton ionization (REMPI) spectroscopy. Although this is not the first time that the IP for carbon has been measured, the measurement was made to an as yet unseen level of accuracy. Additionally, this is the first time that the interseries interactions have been analyzed for the 2pnp states of carbon. This was accomplished by first exciting from the 2s22p2 3Pj (1 = 0, 1,2) ground state up to the 2p3s 3Pj (1 = 0, 1,2) intermediate state with a vacuum ultraviolet (VUV) photon. This enabled a second transition up to the Rydberg states for the respective transitions. The Rydberg states were scanned from a principal quantum number of about 30 to well beyond the ionization limit. From the analysis of these states, the ionization limit for the series converging to the2P1/2 state of the excited core is determined to an accuracy of ±0.05 cm-1. Additionally, the series interactions occurring within the Rydberg series excited from the 2p3s 3Pj and 2p3s 3P0 states were analyzed to yield quantum defects, interaction matrix elements, and relative dipole matrix elements for comparison to theoretical calculations.