Laser and Fourier-transform spectroscopy of KCa

KCa was produced in a heatpipe oven and its thermal emission spectrum around 8900 cm$^{-1}$ was recorded by a high resolution Fourier transform spectrometer. In addition, many selected transitions of this spectrum between deeply bound vibrational levels of the $\mathrm{X}(1)^2\Sigma^+$ and $(2)^2\Sigma^+$ states were studied using laser excitation to facilitate the assignment of the lines. The ground state is described for $v^{\prime\prime} =$ 0 - 5 and the $(2)^2\Sigma^+$ state for $v^{\prime} =0$ - 8 with rotational levels up to 175. For both states, Dunham coefficients, spin-rotation parameters and potential energy curves are derived.