Photochromic Rhodamines Provide Nanoscopy with Optical Sectioning

Exciting developments: Switching individual photochromic and fluorescent rhodamine amides enables 3D far‐field optical microscopy with nanoscale resolution, excellent signal‐to‐noise ratio, and fast acquisition times. The rhodamine amides can be switched on using two photons, which enables 3D detailed imaging of thick and densely stained samples (such as 5‐μm silica beads (see image) and living cells) to be constructed.