Subnanogram mass measurements on plasmonic nanoparticles for temperature-programmed thermal analysis

Ultrasensitive thermo gravimetric analysis of adsorbed organic molecules has been achieved on an ordered array of gold nanoparticles used as a novel plasmonic nanobalance. Theextinction peaksof the resonating surface plasmon of nanoparticle arrays shift upon loading molecules and return to the original position after a linear temperature rise process. A good correlation exists between the film thickness and magnitude of peak shifts. The detection range of plasmonic nanobalance derived from our results can reach a subnanogram level (1.8 pg on an active area of 100 μm²), which is much lower than those of mechanical or electronic mass-measuring devices. Such high mass sensitivity, combined with the remote detection capability and high-temperature operation of plasmonic sensors, allows the in situ detections of the masses of loaded material and thermally desorbed molecules.