This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We would like to determine the number density of fluorophores per square micrometer on a cover slide using the novel approach of image correlation spectroscopy. Our experiments involve grafting DNA molecules on glass coverslips. Complementary DNA strands containing a fitting molecule are then hybridized to the DNA molecules on the glass. We guess that the density of grafted DNA molecules is about 100 per square micrometer. The DNA is labeled with carboxy-fluorescein as fluorescent marker. We would like to learn the technique of image correlation spectroscopy which would require a low-background fluorescence set up the Resource has with its inverted microscope.