The energy dependence of the integral cross section for the electronic excitation in collisions of K and Hg is investigated for er?ergies between 50 eV and 1500 eV. By the measurement of the spectra of the emitted light the 4*Pjn and the 4*Pla states of poQs.sium are found to be dominant. For these the energy dependence of the cross sections is studied in detail. By the measurement of the polarization the contributions to the 4*P3,* state are differentiated with respect to Im$-1 _ Introduction In this communication we want to report about measurements of excitation cross sections and the polarization of the alkali resonance lines in K-Hg collisions for center of mass energies between 20 eV and 1250 eV. This is the first completed set of our measurements in the series of a systematic study of the alkali-mercury interaction_ The main goal of this paper is to present all the experimental information available from integral excitation cross sections for the particular example of K-Hg. Some aspects of this interaction are very similar to the alkali-rare gas interactions for which many experimental * and theoretical studies (calculation of potentials [3]) have been published. In the context of our studies of the alkali-mercury interaction we have performed a pseudopotential calculation of these systems [4] based on the well-known ground-state interaction [.5] _ More recently the differential cross section of laser excited Na 32P,,, interacting with Hg has been given [6,7J _ Finally the differential cross section with energy analysis of the scattered alkali atoms has been measured [8]. The measurements of this report extend measurements given before by ether groups [9, lo] with respect to both the differentiation of the exit channel and the energy range. * For experiments with collisional excitation see ref. [ l] and for experiments with excited states see ref. [21 and references in these papers-