Spectroscopic analysis on the 5 $^{1}\Sigma_{0}^{+}$, 3 $^{1}\Pi _{1}$, 5 $^{3}\Sigma_{1}^{+}$, and 4 $^{3}\Pi_{1}$ states of the KRb diatomic molecule using a molecular beam

The 5 $^{1}\Sigma^{+}$, 3 $^{1}\Pi $, 5 $^{3}\Sigma_{1}^{+}$, and 4 $^{3}\Pi_{1} \quad \leftarrow \quad X \quad^{1}\Sigma^{+}$ (v'' $=$ 0, 1) states of the KRb diatomic molecule near 440 nm have been identified using mass-resolved resonance enhanced two-photon ionization (RE2PI) in a cold molecular beam. For the 3 $^{1}\Pi $ state, the electronic term values ($T_{e})$ and vibrational constants are determined. From a rotational contour analysis, the $\Omega $ symmetries of the upper electronic states of the observed bands are assigned. Vibrational numberings of the experimentally observed levels of the 5 $^{1}\Sigma^{+}$, 3 $^{1}\Pi $, 5 $^{3}\Sigma_{1}^{+}$ and 4 $^{3}\Pi_{1}$ states, are also assigned. The fitted perturbation constants such as spin-orbit coupling matrix element, rotational temperature, linewith, $T_{v}$, and rotational constants have been determined and used to know line profiles of the rotational spectra.