Lifetime Thermometry Research Articles

Temperature measurements of high-temperature surface in environments with interfering radiation using luminescence lifetime thermometry

Temperature measurements of high-temperature surface in environments with interfering radiation using luminescence lifetime thermometry

Double perovskite quantum dots Cs2AgInCl6: Tb3+/Sm3+/Bi3+ for dual-mode fluorescence temperature sensing

In this research, double perovskite quantum dots Cs2AgInCl6: Tb3+/Sm3+/Bi3+ are synthesized employing a high-temperature thermal injection method. The temperature-dependent emission spectra and the fluorescence decay curves of samples show the quantum dots can be applied to dual-mode temperature sensing employing fluorescence intensity ratio technique (between 656 nm (Sm3+) and 549 nm (Tb3+)) and fluorescence lifetime thermometry (549 nm (Tb3+)), achieving maximal relative sensitivities of 3.24%/K (351 K) and 0.68%/K (373 K), respectively. This study offers valuable insights into the temperature sensing capabilities of these quantum dots, which shows that these quantum dots are promising high-sensitivity dual-mode temperature sensing materials.

Abnormal anti-thermal quenching of Mn2+ and reverse thermal response of Mn2+/Mn4+ luminescence in garnet phosphor for wide-range temperature sensing

This work demonstrated the potential application of cryogenic and above room temperature dual-mode luminescence ratiometric and lifetime thermometry based on the diverse thermal quenching behavior of Mn2+ and Mn4+ ions.

Lifetime thermometry in the third biological window using KMnF3:Yb/Er nanoparticles

We report on Yb3+/Er3+ co-doped KMnF3 nanoparticles used as lifetime-based luminescence thermometers within the NIR-III biological window. The nanoparticles were synthesized using a hydrothermal method. Their structure and morphology were confirmed by X-ray diffraction and transmission electron microscopy. Basic optical characterisation was performed using excitation into the strong Yb3+ 2F7/2→2F5/2 inter-multiplet absorption transitions. Er3+ fluorescence was observed from the 2H11/2, 4S3/2 and 4F9/2 and 4I13/2 multiplets due to both upconversion and downshifting processes. The Er3+ 4I13/2 fluorescence transient was measured at 1525 nm (4I13/2) while exciting at 523 nm; for sample temperatures between 10 K and 400 K. These measurements demonstrate a maximum relative thermal sensitivity Sr of 1.32 %⋅K−1 and a minimum thermal uncertainty of 0.009 K at 150 K in the NIR-III region.

Neural Networks Push the Limits of Luminescence Lifetime Nanosensing.

Luminescence lifetime-based sensing is ideally suited to monitor biological systems due to its minimal invasiveness and remote working principle. Yet, its applicability is limited in conditions of low signal-to-noise ratio (SNR) induced by, e.g., short exposure times and presence of opaque tissues. Herein this limitation is overcome by applying a U-shaped convolutional neural network (U-NET) to improve luminescence lifetime estimation under conditions of extremely low SNR. Specifically, the prowess of the U-NET is showcased in the context of luminescence lifetime thermometry, achieving more precise thermal readouts using Ag2 S nanothermometers. Compared to traditional analysis methods of decay curve fitting and integration, the U-NET can extract average lifetimes more precisely and consistently regardless of the SNR value. The improvement achieved in the sensing performance using the U-NET is demonstrated with two experiments characterized by extreme measurement conditions: thermal monitoring of free-falling droplets, and monitoring of thermal transients in suspended droplets through an opaque medium. These results broaden the applicability of luminescence lifetime-based sensing in fields including in vivo experimentation and microfluidics, while, hopefully, spurring further research on the implementation of machine learning (ML) in luminescence sensing.

Integrated photothermal agents with fluorescence intensity ratio/lifetime dual-mode temperature sensing

Non-invasive photo-thermal therapy (PTT) has been proposed as a powerful method for cancer treatment, in which accurate temperature monitoring is necessary to prevent ineffective therapy or damage to normal cells during the process of PTT. This promotes the design and development of photothermal agents (PTAs) with real-time temperature control and excellent photothermal conversion. Here, the designed dual-function photothermal agents YVO4: Nd3+, Yb3+@IR-780 were obtained, while the temperature detection behavior based on the fluorescence intensity ratio (FIR) of Nd3+ (4F3/2 → 4I11/2) to Yb3+ (2F5/2 → 2F7/2) and the temperature-dependent Yb3+ lifetime were investigated in detail. The advantages of fluorescence lifetime thermometry in the biological field were confirmed by the internal temperature detection of pork tissue through comparison with fluorescence intensity ratio technology. The photo-thermal conversion efficiency of samples YVO4: Nd3+, Yb3+@IR-780 reached about 34.3% and its potential application was also evaluated by the sterilization of E. coli and S. aureus, which shows that IR-780 coated nano-materials have excellent photo-thermal conversion performance. Results illuminated that the present photothermal agents with temperature self-monitoring had a bright future in the process of photothermal therapy.

Energy transfer from VO43− to Sm3+ ions in ɑ-Sr2V2O7 phosphors for full-spectrum warm-WLED device and low-temperature luminescence lifetime thermometry

Novel ɑ-Sr2V2O7: Sm3+ phosphors with color-tunable performance were prepared in this work. The crystal structure, photoluminescence properties, and potential applications were introduced. The efficiency of the energy transfer from the [VO4]3- tetrahedral to Sm3+ was 22.67% at a low doping content of Sm3+ (9 mol%), driven by the dipole-dipole interaction. Interestingly, the ɑ-Sr2V2O7: Sm3+ phosphors emitted a full-spectrum (400–800 nm) emission, and the corresponding chromaticity coordinates were located in a near-warm light region. In the potential applications, the warm-white lighting-emitting diode (warm-WLED) based on ɑ-Sr2V2O7: 0.03Sm3+ phosphor was fabricated and further exhibited high-quality performances with the beneficial color rendering index (CRI = 78.67) and low correlated color temperature (CCT = 2257 K) for indoor illumination. Moreover, the low-temperature (38–298 K) optical thermometry performance was also analyzed with the help of Struck and Fonger's theory. Remarkably, the relative sensitivity has an outstanding value of 3.12% K−1 at 98 K. All the above results evidence that the full-spectrum ɑ-Sr2V2O7: Sm3+ phosphors are expected to apply in full-spectrum warm-WLED devices and low-temperature luminescence lifetime thermometry.

Customizing dual-functional platforms for solid-state lighting and luminescence lifetime thermometry with high sensing sensitivity

By substituting Mn4+ for Te6+ in the [TeO6] octahedron, Mn4+doped SrScLiTeO6 (SSLT) phosphors exhibited a broad excitation band ranging from 200 to 600 nm. Emission spectra of the SSLT: Mn4+ phosphors were recorded under 355 nm excitation, centered at 695 nm on account of the 2Eg→4A2g spin-forbidden transition. The optimum doping concentration was suggested to be 0.1 mol%, and the electric dipole-dipole was the basic interaction for the concentration quenching in this work. The chromaticity coordinates of the optimal 0.1 mol% sample were (0.725, 0.275) and it possessed a high color purity of 94.5%. Besides, the obtained sample exhibited beneficial thermal stability based on peak integral intensity, which is suitable to fabricate light-emitting diode devices for plant lighting (red light) and indoor illumination (white light). Eventually, the sensing sensitivity based on lifetime was also studied ranging from 23 to 498 K and the optimum relative sensing sensitivity (SR) was 7.86% K−1 at 473 K. Thus, Mn4+-doped SSLT: Mn4+ phosphors should be potentially used in solid-state lighting and wide-range optical thermometers.

Intra-cluster energy transfer editing in a dual-emitting system to tap into lifetime thermometry.

The impact of composition control and energy transfer on luminescence thermometry was investigated in a TbIII/EuIII dual-emitting molecular cluster-aggregate, known as {Ln20}. The study of lifetime dynamics sheds new light on how one can take advantage of rational planning to enhance thermometric performance and gaining insights into intriguing optical properties.

Deep-red-emitting phosphors of Mn4+-activated tantalite for high-sensitivity lifetime thermometry and security films.

Herein, single monoclinic phase Mn4+-doped Sr2InTaO6 (SITO) phosphors were reported in terms of both luminescence behaviors and potential applications. The optimal Mn4+-doped SITO (0.3 mol%) exhibited a good color purity of 92.9% in a deep-red region with achromaticity coordinate of (0.707, 0.293). In addition, the local structure of Mn4+ in the SITO matrix was determined. The crystal-field strength was calculated to be approximately 1781.7 cm-1 whereas the nephelauxetic ratio was determined to be 1.04. Furthermore, the flexible SITO:Mn4+-YAG:Ce3+ security film was fabricated for use in anti-counterfeiting applications, which could emit different colors under various lighting sources. The SITO:Mn4+ phosphors exhibited a high sensing sensitivity based on the luminescence lifetime. Consequently, the SITO:Mn4+ phosphors can be employed in bifunctional platforms of luminescence lifetime thermometry and anti-counterfeiting applications.

Charge transfer band excited (Sr,Ba)2YTaO6:Eu3+ reddish-orange-emitting phosphors for luminescence lifetime thermometry and flexible anti-counterfeiting labels

Strong reddish-orange-emitting (Sr,Ba)2YTaO6:Eu3+ phosphors were synthesized via a facile solid-state reaction. Due to the occupation of Y3+ ions in the high symmetry (Oh) sites as an inversion symmetry site, the 5D0 → 7F1 magnetic dipole transition peak was dominant in the (Sr,Ba)2YTaO6:Eu3+ phosphors under the charge transfer band excitation. Both Sr2YTaO6:Eu3+ (SYTO:Eu3+) and Ba2YTaO6:Eu3+ (BYTO:Eu3+) phosphors exhibited good thermal stability and quantum yield. Their luminescence sensing performances (relative sensing sensitivity) were determined to be 0.18% K−1 (BYTO:0.1Eu3+) and 0.13% K−1 (SYTO:0.1Eu3+) with the aid of the Struck and Fonger models. Furthermore, novel deep ultraviolet-excited phosphors-based polydimethylsiloxane flexible light-emitting films were fabricated for anti-counterfeiting applications. Consequently, this work reveals that the strong reddish-orange-emitting (Sr,Ba)2YTaO6:Eu3+ phosphors are suitable for dual-functional applications including luminescence lifetime thermometry and flexible anti-counterfeiting labels.

A theoretical framework for optical thermometry based on excited-state absorption and lifetimes of Eu3+ compounds

Ratiometric optical thermometers correspond to one of the most extensively studied applications of luminescent lanthanide materials in recent years. Even though several systems were studied involving the Eu3+ ion, few of them explore the absorption from the low-lying 7F1 excited state and its dependence on the ligand field (LF) splitting. This work aims to describe various absorption intensity ratios (AIR) that can be built from the excitation or absorption spectrum of the europium (III) ion by using the absorptions from the 7F0 → 5D0 transition and the different ligand field components of the magnetic-dipole allowed 7F1 → 5D0 transition and the influence of the ligand field strength on the relative thermal sensitivity of such AIR constructions. We have shown that several AIR formulas can be obtained, and they can display opposite behaviors concerning the Ligand Field strength, being suitable for different compounds of non-cubic symmetries. In addition, the ligand field influence on the relative thermal sensitivity obtained by the lifetime thermometry of the Eu3+5D0 level has also been explored.

Tailoring of strong orange-red-emitting materials for luminescence lifetime thermometry, anti-counterfeiting, and solid-state lighting applications

Strong orange-red-emitting Ba2LaTaO6:Eu3+ phosphors were designed and applied in various optical applications of luminescence lifetime thermometer, anti-counterfeiting film, and solid-state lighting applications. The crystal structure, elemental composition, asymmetry ratio, and other luminescent behaviors were investigated in detail. Especially, the optimal Ba2LaTaO6:0.1Eu3+ phosphor presented remarkable quantum yield (45.29%) and thermal stability (71.52% at 423 K). Based on the temperature-dependent luminescence decay curves, the maximum relative sensing sensitivity was 0.185 × 10−2 K−1 at 513 K. In addition, a novel anti-counterfeiting technique was introduced. The fabricated polydimethylsiloxane films exhibited three different colors under the irradiations of room light, 254 nm light, and 365 nm light, respectively. Eventually, the packaged light-emitting diode displayed the pure orange-red emission. Briefly, a series of the Eu3+-activated Ba2LaTaO6 phosphors with excellent luminescent properties were characterized and further applied in several optical fields for the first time.

Temperature-dependent excited state lifetimes of nitrogen vacancy centers in individual nanodiamonds

Nitrogen vacancy (NV) centers are fluorescent defects widely employed for thermometry, most commonly via temperature-dependent shifts of their optically detected magnetic resonance. Recently, all-optical approaches based on temperature-dependent features of the NV center fluorescence spectrum have also gained traction. Excited state lifetime thermometry is an all-optical technique that has been implemented using other fluorophores but has not previously been demonstrated for NV centers in individual nanodiamonds (NDs). Here, we report temperature-dependent excited state lifetime measurements of NV centers in individual NDs between 300 K and 500 K. We measure a 32 ± 7.0% and 35 ± 8.3% average decrease in the excited state lifetimes of individual NDs on silicon and glass substrates, respectively, over this temperature range. A linear approximation applicable to nearly all measured NDs yields temperature coefficients of −2000 ± 240 ppm/K and −2600 ± 280 ppm/K for NDs on silicon and glass, respectively. In addition to all-optical operation, single-ND excited state lifetime thermometry offers ∼100 ns temporal resolution and utilizes time-correlated single photon counting measurements ideally suited to low emission intensities, a limiting factor for other NV center thermometry techniques above 700 K. We demonstrate that atomic force microscope nanomanipulation can position individual NDs at critical locations on a sample of interest, enabling single-point temperature measurements that combine ∼100 ns temporal resolution and ∼100 nm spatial resolution. This work also has broader implications for other single-ND excited state lifetime sensing applications, where care is required to avoid conflating changes in temperature and other environmental parameters.

Fast wide-field upconversion luminescence lifetime thermometry enabled by single-shot compressed ultrahigh-speed imaging

Photoluminescence lifetime imaging of upconverting nanoparticles is increasingly featured in recent progress in optical thermometry. Despite remarkable advances in photoluminescent temperature indicators, existing optical instruments lack the ability of wide-field photoluminescence lifetime imaging in real time, thus falling short in dynamic temperature mapping. Here, we report video-rate upconversion temperature sensing in wide field using single-shot photoluminescence lifetime imaging thermometry (SPLIT). Developed from a compressed-sensing ultrahigh-speed imaging paradigm, SPLIT first records wide-field luminescence intensity decay compressively in two views in a single exposure. Then, an algorithm, built upon the plug-and-play alternating direction method of multipliers, is used to reconstruct the video, from which the extracted lifetime distribution is converted to a temperature map. Using the core/shell NaGdF4:Er3+,Yb3+/NaGdF4 upconverting nanoparticles as the lifetime-based temperature indicators, we apply SPLIT in longitudinal wide-field temperature monitoring beneath a thin scattering medium. SPLIT also enables video-rate temperature mapping of a moving biological sample at single-cell resolution.

Real‐Time Thermal Imaging based on the Simultaneous Rise and Decay Luminescence Lifetime Thermometry

The most reliable technique of remote temperature sensing considers either the rise or the decay transient of a luminescent temperature probe. Here, real‐time visible (Vis) and near‐infrared (NIR) thermal imagings based on the simultaneous measurement of the emission rise and decay of transition or lanthanide metal activator are described. A single pulse time‐gated detection method that allows the real‐time mode of the temperature measurement, the emission detection at its highest temporal intensity, and the tunability of the emission detection in terms of time delay and gate width is proposed. Cr‐ZnGaGeO4/ZnGa2O4; Er, Ho, Yb–Y2O3 and Er, Ho, Yb–β‐NaYF4 nanoparticles that display luminescence in the Vis to NIR range (450–1200 nm) with timescales varying from 10 to 100 ms are selected. Maximum relative temperature sensitivity in Vis to Vis and NIR to NIR imaging which exceeds up to a factor of two the values obtained by the standard average lifetime method is achieved. This method applies to any lifetime‐based luminescent thermometer, opening a new avenue in designing accurate and straightforward lifetime thermal imaging systems operating in the Vis to NIR range.

Efficient luminescence lifetime thermometry with enhanced Mn4+-activated BaLaCa1−xMgxSbO6 red phosphors

Mn4+-activated phosphors are of great interest in luminescence lifetime thermometry due to the luxuriant luminescence properties influenced by the locally surrounding crystal field. It is highly desirable to develop effective Mn4+-based luminescence lifetime thermometry through modulating the structural parameters. In this work, by introducing the smaller Mg2+ ions to replace Ca2+ site in the BaLaCaSbO6 matrix, a 4.2-fold enhance in the luminescence intensity, red-shifted from 690 nm to 698 nm, as well as luminescence lifetime increase from 0.212 to 0.951 ms is achieved. These modulations are mainly attributed to the strengthen pressure on the local structure, superior lattice rigidity and suppresses non-radiative transition after the substitution of smaller Mg2+. Interestingly, owing to the obvious thermal quenching behavior of Mn4+ ions in the matrix, effective lifetime-based luminescence thermometry can be realized. Mg2+ dopant results in the improvement of the absolute sensitivity from 1.22 µsK−1 (BaLaCaSbO6:Mn4+@408 K) to 4.88 µsK−1 (BaLaCa0.1Mg0.9SbO6:Mn4+@401 K).

Energy transfer in Tb3+- Yb3+ doubly doped CsGd(MoO4)2 single crystals for contactless thermometry, solid-state lighting and solar cells

ABSTRACT A novel terbium (Tb3+) and ytterbium (Yb3+) co-doped optical quality CsGd(MoO4)2 single crystals were grown by the low-thermal-gradient Czochralski method. Photoluminescence spectra were measured and studied for Tb3+– Yb3+ doubly doped CsGd(MoO4)2 crystals at 77–340 K temperature range. Under 330 nm excitation the main peaks of Tb3+ and Yb3+ emission were observed. Decay curves were obtained for the energy levels 5D4 of Tb3+ and 2F7/2 of Yb3+ in CsGd(MoO4)2 crystals. Decay time for Tb3+ transitions significantly varies at temperatures close to ambient. Such behaviour allows to assume perspective application of this effect for non-contact luminescence lifetime thermometry. The emission colour chromaticity coordinates of CsGd(MoO4)2: Tb3+ -Yb3+ crystals are close to SMPTE (Society of Motion Picture and Television Engineers) standard for green colour, as shown on CIE 1931 diagram. Correlated colour temperature varies from 5538 K at 77 K to 4297 K at 340 K.

Luminescence interference-free lifetime nanothermometry pinpoints in vivo temperature

Luminescence nanothermometry makes non-invasive and real-time temperature readings possible in living animals. However, the spectral fluctuation in tissues and fluids, as well as the interaction between fluorophores and environment hinders accuracy of the thermometry. Here, we report a luminescence lifetime-based nanothermometry which specifically addresses this problem. A temporal based calibration (lifetime sensing) in the NIR range, an endogenous thermal response as well as a polymer encapsulation evading environmental factors, altogether help to pinpoint temperature in vivo. Thanks to the highly condensed Nd-Yb ions in a well-protected tiny core-shell nanocrystal (overall 11 nm), a temperature sensitivity about 2.07% K−1 (with 5% Yb3+ doped nanoparticles) and an accuracy of 0.27 K (with 25% Yb3+ doped nanoparticles) in biological fluids are achieved. Hopefully, combining thermally activated energy transfer nanothermometer with anti-interference lifetime thermometry would provide a more accurate temperature measurement for biological and preclinical studies.

From quencher to potent activator – Multimodal luminescence thermometry with Fe3+ in the oxides MAl4O7 (M = Ca, Sr, Ba)

From quencher to potent activator – multimodal luminescence thermometry with Fe3+ in the oxides MAl4O7 (M = Ca, Sr, Ba).