Tip Enhancement of Upconversion Photoluminescence from Rare Earth Ion Doped Nanocrystals

Abstract

We present tip-enhanced upconversion photoluminescence (PL) images of Er(3+)- and Yb(3+)-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 Er(3+) 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.

Recent Progress on Plasmon-Enhanced Fluorescence

“…More recently, subdiffraction spatial resolution of tip-enhanced UC plasmon luminescence images of UC nanocrystals (NaYF 4 :Er 3+ /Yb 3+ ) on glass substrate was demonstrated, and it was found that plasmon enhanced UC efficiency critically depends upon the process of double photon excitation and HOMO energy transfer between ions located in the UCNP, as shown in Figure 18 [121].…”

“…via adjusting the distance between the particle and UCNP B) The scheme of the activator sensitizer system comprising Yb 3+ and Er 3+ ions in single nanocrystal [121].…”

Local Field Modulation Induced Three‐Order Upconversion Enhancement: Combining Surface Plasmon Effect and Photonic Crystal Effect

“…[ 18,[23][24][25][26][27] On the other hand, photonic crystal, as a kind of material with a periodically varying index, can be used to effectively modulate localized electric fi elds and has been successfully explored to enhance the luminescent intensity of UCNPs. [28][29][30] It is expected that through the combination of surface plasmon and photonic crystal effects, the luminescent intensity of UCNPs can be improved more effectively.…”

Effect of ligand field symmetry on upconversion luminescence in heat‐treated LaBGeO5:Yb3+, Er3+ glass

“…Figure B shows the UC emission spectra of the G(LaBGeO 5 :Yb 3+ , Er 3+ ), GC(LaBGeO 5 :Yb 3+ , Er 3+ ), SCGC(LaBGeO 5 :Yb 3+ , Er 3+ ), and C(LaBGeO 5 :Yb 3+ , Er 3+ ) under excitation by a 980 nm LD (1000 mW). The UC spectra of the G(LaBGeO 5 :Yb 3+ , Er 3+ ) and GC(LaBGeO 5 :Yb 3+ , Er 3+ ) display weak blue (450 nm), green (540 nm), red (670 nm), and near infrared (NIR) (800 nm) emission peaks which are attributed to the 4 F 7 / 2 → 4 I 15 / 2 , 4 S 3 / 2 , 2 H 11 / 2 → 4 I 15 / 2 , 4 F 9 / 2 → 4 I 15 / 2 and 4 S 3 / 2 , 2 H 11 / 2 → 4 I 13 / 2 transitions (Figure C), respectively . In contrast, the SCGC(LaBGeO 5 :Yb 3+ , Er 3+ ) and C(LaBGeO 5 :Yb 3+ , Er 3+ ) show significant enhancement in the red and green emissions, while the blue and NIR emissions disappear.…”