HE-3 TRANSVERSE EXCITED-STATE OCCUPATION IN THIN HE-3-HE-4 FILMS

The discovery that He-3 was occupying transverse excited states at sub monolayer coverages in He-3-He-4 mixture films on a Nuclepore substrat e, was a surprise. In this note we discuss the relationship between th eory and experiment in attempting to understand the physics of this be havior. We first discuss various single-atom-limit calculations of the level spacing between the groundstate and first excited state. We the n introduce a free, quasi-particle picture for analyzing experimental magnetization step data and compare those results with the single-atom -limit calculations. The experiments clearly show excited state occupa tion at submonolayer coverages in contradistinction with the calculati ons. We then briefly discuss a microscopic, semi-phenomenological theo ry which, in agreement with experiment, yields He-3 occupation of the first excited state at submonolayer coverages. The mechanism is a mode l He-3-He-3 effective interaction due to one ripplon exchange. This ef fective interaction is density dependent and very long ranged. It stro ngly modifies the small-le properties of the He-3 self-energy and, in particular, causes the ground-state to first excited state level spaci ng to decrease with increasing He-3 areal density.