MONOLAYER SM FILMS ON TA AND CU SUBSTRATES

We have studied the electronic properties of ultrathin layers of Sm on Ta and Cu substrates using valence-band and resonant photoemission. T he average formal chemical valence of Sm on Ta increases from below 2. 4 at low coverage to the value measured from bulk Sm at higher coverag e, while the valence of Sm on Cu is 3 at low coverage and decreases ab ruptly to the same value measured for Ta substrates at higher coverage . These changes in electronic properties reflect interlayer and intral ayer interactions in these films, particularly the weak Sm-Ta and stro ng Sm-Cu interactions.