Luminescence nanothermometry enables accurate, remote, and all-optically-based thermal sensing. Notwithstanding its fast development, there are serious obstacles hindering reproducibility and ...reliable quantitative assessment of nanothermometers, which impede the intentional design, optimization and use of these sensors. These issues include ambiguities or absence of established universal rules for quantitative evaluation, incorrect assumptions about the mechanisms behind the thermal response of the sensors as well as the dependence of the nanothermometers readout on external conditions and host materials themselves. In this perspective article, we discuss these problems and propose a series of standardization guidelines to be followed. This critical discourse constitutes the first required step towards the ubiquitous acceptance, by the scientific community, of luminescence thermometry as a reliable tool for remote temperature determination in numerous practical biomedical implementations.
Abstract
Judd–Ofelt theory is a cornerstone of lanthanides’ spectroscopy given that it describes 4f
n
emissions and absorptions of lanthanide ions using only three intensity parameters. A ...self-referenced technique for computing Judd–Ofelt intensity parameters from the excitation spectra of Eu
3+
-activated luminescent materials is presented in this study along with an explanation of the parametrisation procedure and free user-friendly web application. It uses the integrated intensities of the
7
F
0
→
5
D
2
,
7
F
0
→
5
D
4
, and
7
F
0
→
5
L
6
transitions in the excitation spectrum for estimation and the integrated intensity of the
7
F
0
→
5
D
1
magnetic dipole transition for calibration. This approach facilitates an effortless derivation of the Ω
6
intensity parameter, which is challenging to compute precisely by Krupke’s parametrisation of the emission spectrum and, therefore, often omitted in published research papers. Compared to the parametrisation of absorption spectra, the described method is more accurate, can be applied to any material form, and requires a single excitation spectrum.
Abstract
The description of luminescent processes and their thermally induced changes, that may be also influenced by the optically active ions concentration, and thus by the various inter-ionic ...processes, is the key to the improved development of luminescence thermometry. A phosphor doped with only trivalent terbium ions was described, which, by using two excitation lines fitted to the
7
F
6
→
5
D
3
and
7
F
5
→
5
D
3
transitions, shows a luminescent signals with the opposite characteristics of intensity changes as a function of temperature. By modifying the concentration of Tb
3+
ions, the probability of {
5
D
3
,
7
F
6
} ↔ {
5
D
4
,
7
F
0
} cross-relaxation was being altered, which turned out to have a beneficial effect on the properties of the described nanothermometers. The ratio of intensities for both excitations was found to be temperature dependent, which resulted in high relative sensitivities of temperature readout reaching 3.2%/°C for 190 °C and not reaching values below 2%/°C in the broad range of the temperature. Extensive decay time measurements for
5
D
3
and
5
D
4
emissive levels were presented and the variability of both rise- and decay times as a function of terbium concentration and temperature was investigated. Thanks to this, conclusions were drawn regarding thermally dependent optical processes occurring in a given and similar systems.
It is the most personal article I have ever written, revealing my fears, hesitations, reflections, and decisions. I am still striving to write a scientific and academic paper, still looking for that ...academic framework that would allow this article to be recognized as a scientific text, with the reflection on that internal pressure and need to make it scientific. This is an article about the process of becoming an autoethnographer, creating a tool, shaping identity and research strategy, and becoming one.
In colloidal methods, the morphology of nanoparticles (size and shape) as well as their stability can be controlled by changing the concentration of the substrate, stabilizer, adding inorganic salts, ...changing the reducer/substrate molar ratio, and changing the pH and reaction time. The synthesis of silver nanoparticles was carried out according to the modified Lee and Meisel method in a wide pH range (from 2.0 to 11.0) using citric acid and malic acid, without adding any additives or stabilizers. Keeping the same reaction conditions as the concentration of acid and silver ions, temperature, and heating time, it was possible to determine the relationship between the reaction pH, the type of acid, and the size of the silver nanoparticles formed. Obtained colloids were analyzed by UV-Vis spectroscopy and investigated by means of Transmission Electron Microscope (TEM). The study showed that the colloids reduced with citric acid and malic acid are stable over time for a minimum of seven weeks. We observed that reactions occurred for citric acid from pH 6.0 to 11.0 and for malic acid from pH 7.0 to 11.0. The average size of the quasi-spherical nanoparticles changed with pH due to the increase of reaction rate.
The article briefly presents the empirical results of a large research project focused on Polish urban marketplaces, commonly known as bazaars, and their interactional order. Due to the spatial ...separation and legal regulations concerning bazaar trade, a relatively constant community of market vendors is created in the area of the particular marketplace. The primary activity of each merchant is to offer and sell goods; however, the specificity of marketplace trade results in the necessity to maintain relationships with other vendors to keep this primary activity going. Thus, the activities of merchants are carried out in the same direction for both economic results and performance (sales and profit) and social action, that is, building and managing relations with vendors operating in the same marketplace. A wide range of activities and interaction strategies is developed that create an order of interactions between vendors, both in terms of perceiving and assigning meanings, interpreting, and taking actions. The consequences of such an interactional foundation affect the economic layer of the market, embedding, on the one hand, economic phenomena in social phenomena, and, on the other hand, generating paradoxes of prices and competition—the two economic concepts that cannot be analyzed without their social contexts.
A new approach to enhance the sensitivity of transition metal ion based nanocrystalline luminescent thermometer is presented. It was shown that the increase of Cr
3+
concentration in three types of ...garnet host namely Y
3
Al
5
O
12
, Y
3
Ga
5
O
12
, and Y
3
Al
2
Ga
3
O
12
allows for significant enhancement of their performance in non-contact thermometry. This phenomenon is related to the weakening of the crystal field strength due to enlargement of average Cr
3+
-O
2−
distance at higher Cr
3+
concentrations. By increasing Cr
3+
concentration from 0.6 to 30%, the sensitivity increased by over one order of magnitude from
S
= 0.2%/°C to
S
= 2.2%/°C at 9°C in Y
3
Al
2
Ga
3
O
12
nanocrystals. Moreover, it was found that due to the Cr
3+
→ Nd
3+
energy transfer in the Cr
3+
, Nd
3+
co-doped system, the usable Cr
3+
concentration, for which its emission can be detected, is limited to 10% while the sensitivity at −50°C was doubled (from 1.3%/°C for Y
3
Al
2
Ga
3
O
12
:10%Cr
3+
to 2.2%/°C Y
3
Al
2
Ga
3
O
12
:10%Cr
3+
, 1%Nd
3+
nanocrystals).
The possibility of using Pr3+ ions to develop multicolor‐emission‐based luminescence thermometry in a single‐band‐ratiometric configuration is investigated for the first time. The thermally induced ...decrease in intensities of 3P0 → 3F2 and 1D2 → 3H4 emission bands is demonstrated using the excitation matching the ground‐state absorption, and an inverse relation is obtained using the optical excitation matching the excited‐state absorption. The strategy of modulation of the thermometric properties of the Pr3+‐based red‐ and yellow‐emitting single‐band ratiometric (SBR) luminescent thermometers by the activation of the cross‐relaxation (CR) phenomenon promoted by the dopant concentration is elaborated. Contrary to expectations, the {3P0,3H4} ↔ {1D2, 3H6} CR process is shown to cause the high and low dopant concentrations to be optimal for highly sensitive SBR luminescent thermometers operating in the red and yellow spectral ranges, respectively. In both cases, high relative sensitivities of the temperature readout are obtained. These results make Pr3+ ions promising candidates for a SBR thermometry approach.
The first example of Pr3+‐based luminescence thermometry in a single‐band‐ratiometric approach is demonstrated. Due to the efficient cross relaxations, bands in the red and yellow spectral ranges are analyzed at high and low dopant concentrations, respectively. High temperature readout sensitivity is obtained using excitations matched to ground‐ and excited‐state absorption. The underlying thermally dependent optical phenomena are broadly discussed.
The up-conversion (UC) phenomenon is a well-known process based on anti-Stokes emission observed in materials doped with luminescent ions. Several factors lead to UC and IR colour changes. Usually, ...various dopants with emission in whole VIS region are used to change colours. This paper is focused on the factors that can change the colour of the Yb – Er UC and IR emission. Complex measurements were done in a wide range of temperatures to check the dependence of several factors on Stokes and anti-Stokes emission of the Lu2O3:Er3+,Yb3+ system. It was found that the size of the grains have the highest impact on the spectroscopic properties of the Lu2O3:Er3+,Yb3+. For the smallest particles also Yb/Er concentration ratio, temperature of the measurement and incident laser power have a great impact on both types of the emission colour.
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•The impact of several factors on UC and IR luminescence are presented and discussed.•EXAFS/XANES analysis of the materials is presented.•All spectroscopic properties are examined in range of temperatures (−100 to 400 °C).•Temperature sensing of Lu2O3:Yb3+,Er3+ powders was checked and analyzed.•Stokes and anti-Stokes emission from Er3+ ions was analyzed.
•Luminescent thermometer based on SrTiO3:Mn4+ nanocrystals has been synthesized.•The multimodal temperature readout using this luminescent thermometer was presented.•The readout multimodality ...enhances the reliability of the temperature sensing.•Obtained S are one of the highest already reported for thermometers based on Mn4+.
The constant striving to improve the quality of thermal imaging with the use of luminescent thermometers imposes the search for new materials with better and better thermometric properties. The facility in the modulation of the spectroscopic properties of transition metal doped materials makes them particularly attractive for this type of application. Therefore, in response to this expectation, in this manuscript we report the novel SrTiO3:Mn4+ nanocrystals as a thermographic phosphor of extraordinary thermometric properties in the biologically relevant temperatures. The high relative sensitivity of the SrTiO3:Mn4+ nanocrystals to temperature changes in each of the three temperature readout modes presented in this manuscript, namely 8.67%/K at 313 K in the intensity mode, 3.5%/K at 348 K in the lifetime mode and 5.64%/K at 303 K in the ratiometric mode, make this material one of the most promising candidates for highly sensitive temperature imaging.
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