Optical fluorescence of biological samples using STJs

We have recently reported on the first use of tantalum/aluminium single pixel Superconducting Tunnel Junctions (STJs) in biological fluorescence measurements [G.W. Fraser, et al., Rev. Sci. Instrum. 74 (2003) 4140]. In this paper, we present optical spectra from multiple biological fluorophores bound to DNA. The data confirm, in a real biological context, the advantages of STJs over conventional photomultiplier or avalanche photodiode based detectors. The STJʹs, resolving power E/ΔE>10, together with appropriate band-pass filtering, allows the preferential detection of individual fluorophores and permits the removal of auto-fluorescent emission from the microscope lens.