Photon upconversion
Photon upconversion (UC) is a process in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength. It is an anti-Stokes type emission. An example is the conversion of infrared light to visible light.[1][2][3] Materials by which upconversion can take place often contain ions of d-block and f-block elements. Examples of these ions are Ti2+, Ni2+, Mo3+, Re4+, and Os4+.
Three basic mechanisms are energy transfer upconversion, excited-state absorption (ESA) and photon avalanche (PA). Upconversion should be distinguished from two-photon absorption and second-harmonic generation. An early proposal (a solid-state IR quantum counter) was made by N. Bloembergen in 1959[4] The process was first observed by F. Auzel in 1966[5][6]
References
- ^ Haase, M. and Schäfer, H. (2011), Upconverting Nanoparticles. Angewandte Chemie International Edition, 50: 5808–5829. doi:10.1002/anie.201005159
- ^ Upconversion and Anti-Stokes Processes with f and d Ions in Solids François Auzel Chem. Rev., 2004, 104 (1), pp 139–174 doi:10.1021/cr020357g
- ^ Design of Luminescent Inorganic Materials: New Photophysical Processes Studied by Optical Spectroscopy Daniel R. Gamelin and Hans U. Güdel Acc. Chem. Res., 2000, 33 (4), pp 235–242 doi:10.1021/ar990102y
- ^ Solid State Infrared Quantum Counters Bloembergen, N. Phys. Rev. Lett.,2, 84 1959 doi:10.1103/PhysRevLett.2.84
- ^ F. Auzel, C. R. Acad. Sci. 1966, 262, 1016
- ^ F. Auzel, C. R. Acad. Sci. 1966, 263, 819