Optical–optical double resonance with two dye lasers: Rotational analysis of the E 2Σ–B2Σ system of Ca35Cl

Abstract

A complete rotational analysis of the E ²Σ–B ²Σ system of CaCl has been accomplished using two tunable dye lasers. The first cw laser is tuned to a known B ²Σ–X ²Σ transition to produce a finite concentration of molecules in a particular quantum state. Subsequently, a second pulsed dye laser is used to record the E ²Σ–B ²Σ excitation spectrum from this state prepared level. The method vastly simplifies an otherwise congested molecular spectrum. The data are combined with previous microwave measurements on the X ²Σ state and optical data on the B ²Σ–X ²Σ system to give the following molecular constants (cm⁻¹). Uncertainties are 95% confidence limits in the last digit.