A high dispersion study of some new absorption bands of CaH and CaD in the ultra-violet region

King furnace spectra of CaH and CaD at temperatures greater than 1200 °c have been obtained in absorption. Five new bands of CaH at 2815 Angstrom, 2752 Angstrom, 2609 Angstrom, 2580 Angstrom, 2535 Angstrom and two new bands of CaD at 2711 Angstrom and 2646 Angstrom have been measured and analysed. Of these, the two CaD bands and the first three CaH bands have been shown to be extensions of some of the systems already reported. The CaH bands at 2580 Angstrom and 2535 Angstrom, however, have been analysed as the (0, 0) bands of two different systems, which may be called H 2 Σ -> X 2 Σ and I 2 Σ -> X 2 Σ transitions, respectively. Rotational constants have also been calculated where necessary.