Webinar on June 30, 2021, 3:00 pm UTC+2

Quantitative Nanomechanical Photothermal Microscopy

We are investigating photothermal microscopy based on nanoelectromechanical systems (NEMS) in our group at TU Wien. In typical photothermal microscopy, a sample is illuminated with heating radiation, and the resulting photothermal heating is detected from the thermo-optical response. In NEMS-based photothermal microscopy, the photothermal sample heating is directly measured by a temperature-sensitive substrate. This sample substrate is a nanoelectromechanical drum that oscillates at its resonance frequency. The photothermal heating of the sample causes a thermal expansion of the drum. As a result, the drum’s frequency detunes in response. The induced frequency detuning is proportional to the photothermal heating power. Using a stress-reduced 50 nm thick silicon nitride drum, we have detected the photothermal signal of single molecules with a large signal-to-noise ratio [1]. With its fW-sensitivity, NEMS-based photothermal microscopy presents a potent platform for single-molecule absorption spectroscopy.

1. M.-H. Chien, M. Brameshuber, B. K. Rossboth, G. J. Schütz, S. Schmid, PNAS 115 (2018), 11150–11155.