Unraveling the Electronic Structures of Neodymium in LiLuF₄ Nanocrystals for Ratiometric Temperature Sensing

Abstract

Nd 3+ ‐doped near‐infrared (NIR) luminescent nanocrystals (NCs) have shown great promise in various bioapplications. A fundamental understanding of the electronic structures of Nd 3+ in NCs is of vital importance for discovering novel Nd 3+ ‐activated luminescent nanoprobes and exploring their new applications. Herein, the electronic structures of Nd 3+ in LiLuF 4 NCs are unraveled by means of low‐temperature and high‐resolution optical spectroscopy. The photoactive site symmetry of Nd 3+ in LiLuF 4 NCs and its crystal‐field (CF) transition lines in the NIR region of interest are identified. By taking advantage of the well‐resolved and sharp CF transition lines of Nd 3+ , the application of LiLuF 4 :Nd 3+ NCs as sensitive NIR‐to‐NIR luminescent nanoprobes for ratiometric detection of cryogenic temperature with a linear range of 77–275 K is demonstrated. These findings reveal the great potential of LiLuF 4 :Nd 3+ NCs in temperature sensing and also lay a foundation for future design of efficient Nd 3+ ‐based luminescent nanoprobes.

Non-stoichiometry in Ca2Al2SiO7 enabling mixed-valent europium toward ratiometric temperature sensing

“…Essentially, the FIR-based temperature sensing is achieved by monitoring two discriminable emission peaks as the signals whose responses to temperature are significantly different. So far, the thermally coupled levels (TCL) of many rare earth ions (such as Er 3+ : 4 S 3/2 / 2 H 11/2 [17,18]; Ho 3+ : [19,20]; Nd 3+ : 4 F 7/2 / 4 F 3/2 [21]), and transition metal ions (such as Cr 3+ : 2 E/ 4 T 1 [22,23]), are often utilized as temperature probes. With variation of temperature, electron populations at the lower and upper level of TCL could change oppositely, resulting in varied FIR.…”

Lanthanide near-infrared emission and energy transfer in layered WS2/MoS2 heterostructure

“…Lanthanide ions have conventionally been doped into semiconducting or transparent insulating substrates as active centers to emit photons, which cover the ultraviolet (UV), visible, NIR, and mid-infrared (MIR) region [15,16]. Since lanthanide ions have abundant 4f energy states, their emission possess the benefits of high quantum yield, high optical stability, narrow bandwidth, and long lifetime [17,18]. At present, lanthanide-doped optical materials have been broadly applied in many op-toelectronic and photonic technologies, including solidstate lighting, telecommunication, biomedicine, etc.…”

Single‐Cell Biodetection by Upconverting Microspinners

“…Then, NaYF 4 microparticles with other activators (including those leading to down conversion emission) would be also perfectly suitable for optical driven spinning and, therefore, for single‐cell detection. Also, other birefringent microparticles (such as LiREF 4 or other hosts microparticles) could be used as spinners . The spinner composition, by adjusting dopants or host materials, could help optimising its multifunctional properties, such as for example spinners fluorescence brigtness, concominant optical temperature readout, optical heating, or spinning velocity determination based on fluorescence fluctuations.…”