  Multicomponent lipid mixtures exhibit complex phase behavior, including
coexistence of nanoscopic fluid phases in ternary mixtures mimicking the
composition of the outer leaflet of mammalian plasma membrane. The physical
mechanisms responsible for the small size of phase domains are unknown, due in
part to the difficulty of determining the size and lifetime distributions of
small, fleeting domains. Steady-state FRET provides information about the
spatial distribution of lipid fluorophores in a membrane, and with an
appropriate model can be used to determine the size of phase domains. Starting
from a radial distribution function for a binary hard disk fluid, we develop a
domain size-dependent model for stimulated acceptor emission. We compare the
results of the model to two similar, recently published models.
