Predicting observable infrared signatures of nanosilicates in the diffuse interstellar medium.

The destruction time scale of dust in the diffuse interstellar medium is estimated to be an order of magnitude shorter than its residence time. Nevertheless, dust is observed in the interstellar medium, leading to the conclusion that reformation and grain growth must take place. Direct observations of nanometre-sized silicate grains, the main constituent of interstellar dust, would provide a smoking gun for the occurrence of grain condensation in the diffuse interstellar medium.