Infrared quantum counter

The lifetimes of R in YCI3 have been studied (Gandrud and Moos, 1968) by the infrared quantum counter and infrared fluorescence techniques for R = Ho, Er and Tm. The differential magnetic susceptibility of H0CI3 and HoiYCU has been reported by Hellwege et al. (1968). The electron spin resonance of the excited state S3/2 of ErrYCU has been detected by Furrer et al. (1971). 

Upconversion materials, which emit high-energy photons under excitation by the NIR light (anti-Stokes shift) were first discovered in the 1960s, but have primarily been exploited for the development of some remarkably effective optical devices such as infrared quantum counter detectors, ... 

Chivian JS, Case WE, Eden D (1979) Photo avalanche-new pnenomenon in Pr-3(+)-based infrared quantum counters. Appl Phys Lett 35 124-125... 

The term upconversion describes an effect [1] related to the emission of anti-Stokes fluorescence in the visible spectral range following excitation of certain (doped) luminophores in the near infrared (NIR). It mainly occurs with rare-earth doped solids, but also with doped transition-metal systems and combinations of both [2, 3], and relies on the sequential absorption of two or more NIR photons by the dopants. Following its discovery [1] it has been extensively studied for bulk materials both theoretically and in context with uses in solid-state lasers, infrared quantum counters, lighting or displays, and physical sensors, for example [4, 5]. Substantial efforts also have been made to prepare nanoscale materials that show more efficient upconversion emission. Meanwhile, numerous protocols are available for making nanoparticles, nanorods, nanoplates, and nanotubes. These include thermal decomposition, co-precipitation, solvothermal synthesis, combustion, and sol-gel processes [6], synthesis in liquid-solid-solutions [7, 8], and ionothermal synthesis [9]. Nanocrystal materials include oxides of zirconium and titanium, the fluorides, oxides, phosphates, oxysulfates, and oxyfluoiides of the trivalent lanthanides (Ln ), and similar compounds that may additionally contain alkaline earth ions. Wang and Liu [6] have recently reviewed the theory of upconversion and the common materials and methods used. 

Localized interactions Infrared quantum counter Phosphor Photographic film... 

---