Activation of caged fluorophores has mostly relied on the absorption of either a single ultraviolet photon or two NIR photons. Here, the authors show that two green photons (515 nm) can substitute for a single photon ( ~ 260 nm) to activate rhodamine-based dyes, thus enabling STED imaging in thick samples.
- Jan-Erik Bredfeldt
- Joanna Oracz
- Stefan W. Hell
