Signal size and resolution of scanning thermal microscopy in air and vacuum.

We present measurements comparing scanning thermal microscopy in air and vacuum. Signal levels are compared and resolution is probed by scanning over the edge of a nanofabricated Ag square embedded in [Formula: see text]. Signals measured in air were seen to be 2.5-40 times larger than in vacuum. Furthermore, the air signals were stable while the vacuum signals varied significantly. Edge widths measured in air were approximately 39% larger than those measured in vacuum. Our observations are consistent with the air measurements experiencing heat transfer from the surrounding sample through the air as well as the formation of a water-related meniscus at the tip-sample junction. These results contribute to the understanding of the complex heat exchange effects that can occur in scanning thermal microscopy when it is conducted in an ambient atmosphere.