Sunday, 15 March, 2015

Tip Enhancement of Upconversion Photoluminescence from Rare Earth Ion Doped Nanocrystals

N. Mauser, D. Piatkowski, T. Mancabelli, M. Nyk, S. Mackowski, A. Hartschuh -
ACS Nano DOI: 10.1021/nn504993e (2015)

We present tip-enhanced upconversion photoluminescence (PL) images of Er3+- and Yb3+-doped NaYF4 nanocrystals on glass substrates with subdiffraction spatial resolution. Tip sample distance dependent measurements clearly demonstrate the near-field origin of the image contrast. Time-resolved PL measurements show that the tip increases the spontaneous emission rate of the two emission channels of Er3+ in the visible region. Very efficient enhancement of upconversion PL is discussed in the context of the two-photon nature of the excitation process and homoenergy transfer between the ions within the nanocrystals. Comparison between different nanocrystals and tips shows a strong influence of the tip shape on the image contrast that becomes particularly relevant for the larger dimensions of the investigated nanocrystals.

Article on journal`s website