INTERRELATION BETWEEN ATOMIC AND ELECTRONIC-STRUCTURES OF ALKALINE-EARTH ADLAYERS ON MO(112) AND RE(10(1)OVER-BAR-0)

A pronounced correlation between electronic structure and two-dimensio nal phase transitions in Mg, Sr and Ba monolayers on (112)Mo and (1010 BAR)Re surfaces is found by LEED, UPS and LEELS techniques. At low cov erages, the adsorbed atoms are arranged in linear chains oriented acro ss the rows of substrate atoms, while UPS and LEELS indicate the appea rance of adsorption induced resonances. At 0>0.5 the commensurate-inco mmensurate transition is accompanied by sharp changes in photoemission spectra and emergence of energy losses due to plasmon excitations rev ealing the metallization of the adlayers.