Perceiving Linear-Velocity by Multiphoton Upconversion

Abstract

Up to now, the rising edge of the upconversion process does not receive due attention. Herein, a demonstration utilizing the feature of the rising edge to practically detect the linear-velocity of an object is presented. Typically, upconversion processes with different numbers of participant photons would exhibit diversity in the rising edge. On this account, when the emitter is moving, the emission intensity ratio of different multiphoton processes will vary with changing linear-velocity, which enables accurate speed detection through spectral analysis. To illustrate this principle, in this work, the modeling and numerical simulation were first performed, and then experimental demonstration was carried out in which core−shell upconversion nanocrystals were elaborately designed and fabricated as the speed sensing probe to calibrate the speed of a homemade turnplate. It is believed that the present work will exploit a novel speed sensing method and find a new application for lanthanide-doped upconversion materials.

Pumping-controlled multicolor modulation of upconversion emission for dual-mode dynamic anti-counterfeiting

“…The emission color of the stamped patterns achieved with NaErF 4 : 10Yb@NaYF 4 @NaYbF 4 : 20Ca/1Tm@NaYF 4 NCs (124 nm, Figure S15a) and NaErF 4 : 10Yb@NaYF 4 @NaYbF 4 : 20Li/20Ca/1Tm@NaYF 4 core/triple-shell NCs (57 nm, Figure S15b), which were invisible under daylight, changed evidently with the increase of the excitation power density. It has been reported that Er 3+ and Tm 3+ ions in the Yb/ Tm:NaGdF 4 @NaYF 4 @Yb/Er:NaGdF 4 core/dual-shell NCs showed temporal color separation owing to their different rising edge in the decay life-time curves [39]. As shown in Figure S16, the rising edge among the transitions of 1 G 4 → 3 H 6 , 1 D 2 → 3 H 6 , Er 3+ : 4 S 3/2 → 4 I 15/2, and 4 F 9/2 → 4 I 15/2 as well as their corresponding life-time are distinctly different, hence, temporal multicolor is anticipates to be achieved with rotating the as-prepared patterns.…”

The Key Role of Intrinsic Lifetime Dynamics from Upconverting Nanosystems in Multiemission Particle Velocimetry

“…This type of calibration applies to the majority of velocimetry methods based on the use of a luminescent probe, whose luminescent profile can be recorded and calibrated with varying the flow velocity. [3][4][5] Lanthanide-doped upconverting nanoparticles (UCNPs) have been previously adopted for velocity measurements, and the ratio between specific emissions provided the velocity after calibration. [4][5] The limitations of these methods reside in the propagation of the errors to the measured velocities arising from the external parameters used for calibration and from the deconvolution of the luminescence profile, and the necessity to repeat the calibration after any modifications of the experimental setup.…”

“…Also, it requires calibration of the CIE coordinates with time, resulting in a similar approach to the ones already reported in the literature. [3][4][5] A more flexible way to obtain the particle velocities, without any need for calibration, is achieved by applying blue and green bandpass filters (BP450 and BP540, respectively) to capture the flow as images. In contrast to the color-coordinate method, the influence of the sensitivity of different detectors does not constitute a source of error when the multiple emissions are recorded separately.…”

“…This multiemission approach provides the steady-state velocity of the particles with a very simple luminescence imaging setup and without any need for calibration. With respect to the other methods, [3][4][5][6][7][8][9][10][11][12][13] only two images are needed to establish the travelled distance by these nanoprobes, allowing for maximum flexibility of their use and reducing the experimental error. With respect to MTV, [12,13] the proposed approach yields the same 1D information without the necessity for multiple excitation sources or detectors.…”

Morphology control and temperature sensing properties of micro‐rods NaLa(WO4)2:Yb3+,Er3+ phosphors

“…Over the decades, lanthanide (Ln 3+ )‐doped materials have been widely applied in broad areas owing to the excellent optical, electrical, and magnetic properties, such as color display, solar cells, detection technology, and temperature sensors 1‐9 . Recently, Ln 3+ ‐doped materials have attracted significant attention in the area of biotechnology as fluorescent and thermal probes.…”