Total Internal Reflection Fluorescence (TIRF)

Total Internal Reflection Fluorescence (TIRF) is a microscopy technique that leverages a special light behavior to visualize molecules near a surface. When light hits the boundary between two materials at a specific angle, it reflects entirely rather than passing through—this is called total internal reflection. However, this creates a thin, energized zone known as an evanescent wave, which excites fluorescent molecules very close to the surface (typically within 100 nanometers). TIRF allows scientists to observe interactions and processes at the cell membrane or surface with high sensitivity and low background noise, making it ideal for studying biological events at the molecular level.