User:ETstem/Two-photon photoelectron spectroscopy

Variations and Applications
Two-photon excitation has many different applications and uses in the scientific field. Because of its ability to image three-dimensionally, two-photon excitation can be used in experiments that involve localized uncaging of molecules, imaging of fluorescent-tagged proteins or cells, and measuring electrical activity such as via calcium indicators.

Two-photon microscopy, while comparable to confocal microscopy, holds distinct advantages over other imaging techniques. Specifically, two-photon microscopy is advantageous as it applies to three dimensional imaging of live cells and tissues. The main advantages of two-photon microscopy are “reduced phototoxicity, increased imaging depth, and the ability to initiate highly localized photochemistry in thick samples”.

Two-photon photoemission spectroscopy is used in studying metals and surfaces. 2PPE is advantageous because it allows high-resolution detection of both occupied and unoccupied excited states of electrons in molecules, but is generally limited to the surfaces of samples. Another variation of photoemission spectroscopy is spectroscopic photoemission and low energy electron microscopy (SPELEEM), which can be used to determine electron structures in a small area of a sample.