Knowledge Bank

There have been many spcctroscopic studies of the low-lying or valence states of the alkaline earth monohalidcs (MX) in recent years. These states are well represented by a simple physical model where there is a lone non-bonding electron centered on the metal ion. These M+ states are perturbed by the electrostatic field of X-acting at a distance Re. Although this model has succesfully described the X, A. B and C states CaF, where of the $Ca+4s,4p$ and 3d states is considerably less than Re, it cannot be used to represent Rydberg states where will be greater than Re. The core-penetrating (r<Rc) s,p and d Rydberg orbitals will however show evidence of their relationship to their core precursors through their quantum defects. We have observed and assigned according to A, v and J. 68 vibronic states of CaF in the region from $40600cm-1$ to $45905cm-1$ using pulsed optical-optical double resonance via the $A\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi 3/2$ state. O.O.D.R. transitions are detected by observation of direct UV fluorescence. These states have been organized into 18 Rydberg series ($3\Sigma$ series ($3\Sigma$ series, $2\Pi$ series and $1\Delta$ series converging to v=0, 1 and 2 levels of the ion) and this has enabled us to make an improved estimate of the CaF jonization potential $(v=0ofCaF+)$ at $47005cm-1\pm 20cm-1$. These series are shown to extrapolate to previously observed low Rydberg and valence states, thus allowing assignments of absolute quantum defects. Using this information in conjunction with preliminary measurements of spin-orbit and spin-rotation constants, we have assigned the series according to n and 1. We have observed all of the A components of the core penetrating s,p, and d Rydberg series in the region from $n\ast =4$ to $n\ast =10$. This is consistent with exitation out of the $A2\Pi 3/2$ state which has been shown from ligand field calculations to be mixture of $Ca+4p$ and 3d states. Reasons for the absence off states in our spectra will be dicussed