[摘要]:Two-dimensional ex situ nanothermometers are demonstrated using single crystal silver nanospheres. The nanothermometers can record the maximum temperatures experienced by the nanospheres and can be read later with a nanometer-scaled spatial resolution, which is very much desired for the situations where in situ temperature readout is not possible, such as in explosions. The temperature is detected based on the temperature-dependent diameter and areal density of single crystal silver nanospheres formed on carbon films.