Energy transfer upconversion in and doped crystals

Abstract

A comparative spectroscopic study for and doped crystals has been realised at liquid nitrogen temperature. The single-doped sample shows principally blue emission corresponding to the transition, whereas the codoped sample gives rise to a very efficient green emission which is ascribed to the transition. The total integrated upconversion emission intensity (including blue and green emissions) for the codoped crystal is three times more intense than that of the doped one, while the ratio for green emission rises to 27. The green emission in the codoped sample results mainly from the mixed centre, whereas the blue emission is essentially due to the pair. Two energy transfer upconversion mechanisms have been proposed and are discussed in the paper.

Up-conversions in Ho3+ doped tellurite glass

“…Co doping the host with Yb 3+ ions along with any one of the Er 3+ , Ho 3+ or Tm 3+ ions has been shown to be effective in enhancing up-conversion efficiency [25][26][27][28][29]. In this paper, we report the observation of up-conversion emission in red, green and blue regions from Ho 3+ in LiTeO 2 glass.…”

Resonance Energy Transfer: Theoretical Foundations and Developing Applications

“…(14.29) contributes a diagonal rate term that in the short range runs as 6 6 R R     , producing a sum expressible as Similar principles operate in sensitisation processes. 53 Here, the transfer of excitation from a donor ion A* to an acceptor C engages a bridging species B, without which the transfer is ineffective. Once again, the term 'up-conversion' is common for such observations, but 'sensitisation' distinguishes it from the pooling processes described above.…”

Energy harvesting: a review of the interplay between structure and mechanism

“…The clearest case is frequency up-conversion, based on the same mechanisms of energy pooling that operate in multichromophore molecules [84]. In general, this fluorescence owes its origin to energy transfer mechanisms involving three chromophore/fluorophore sites, with two acting as donors and one as acceptor [85][86][87]. Exploiting such an effect, it is possible to tailor such materials specifically for stepwise or sequential laser frequency up-conversion.…”