The C1Πu state of potassium dimer revisited: An extensive study by polarisation labelling spectroscopy method

The polarisation labelling spectroscopy technique was applied to study the C1Πu ← X1Σg+ band system in potassium dimer. About 1100 new rotationally resolved molecular lines were measured in the 22100–24100 cm−1 spectral range. Perturbations of the lowest vibrational levels of the C state were localised and their origin discussed. A set of Dunham coefficients was deduced to fit the unperturbed levels of the C1Πu state with 0≤v≤38 and 18≤J≤101 and the potential energy curve of the state was constructed.