Ultraviolet Absorption Spectrum of the CaH Molecule I. Rotational analysis of the 3 060 Å band system

Abstract

Four new violet degraded bands of CaH have been observed in absorption in the region 2 900 to 3 200 Å by heating calcium and hydrogen to 1 200-1 400°C. Rotational analysis indicates that the bands belong to two close-lying systems K 2 Σ + - X 2 Σ + and L 2 Π - X 2 Σ + which are separated by similar 50 cm -1 for the 0-0 bands. The rotational levels for the excited states approximate to Hund's case (d) coupling with L = 1. A Hamiltonian matrix has been constructed for the two states and constants for the "unperturbed" states evaluated. These constants reproduce the experimental term values to within 0.2 cm -1 , except for levels involved in local perturbations.