Carriers of the astronomical 2175 ? extinction feature

摘要: The 2175 {angstrom} extinction feature is by far the strongest spectral signature of interstellar dust observed astronomers. Forty years after its discovery origin and nature carrier remain controversial. enigmatic because although central wavelength almost invariant bandwidth varies strongly from one sightline to another, suggesting multiple carriers or a single with variable properties. Using monochromated transmission electron microscope valence energy-loss spectroscopy we have detected 5.7 eV (2175 {angstrom}) in submicrometer-sized grains within interplanetary particles (IDPs) collected stratosphere. are organic carbon amorphous silicates that abundant closely associated another both IDPs medium. Multiple rather than may explain astronomical feature.