The Kaiser (K) is a unit of energy. A common form is kiloKaiser (kK). 1 kK = 1000 cm−1. ( cm−1, wavenumber or inverse wavelength.) This unit is most commonly used with respect to energy transitions between electronic states in inorganic complexes.
Kilokaiser is a common but incorrect spelling of the unit KiloKayser, which equals 1000 wavenumber (cm−1). The unit is named after Heinrich Gustav Johannes Kayser (16 March 1853 – 14 October 1940), a German physicist.