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[en] There is a long history of using the Er3+ ion’s 2H11/2/4S3/2–4I15/2 transitions for ratiometric thermal sensing. As demonstrated previously, these two transitions can be triggered via up- and down-conversion mechanisms. However, little attention is focused on the influence of these two mechanisms on the sensing performance for the 2H11/2/4S3/2–4I15/2 transitions. It was demonstrated here the as-prepared CaWO4:Yb3+, Er3+ phosphors could be effectively triggered by both the 980 and 405 nm laser diodes to generate the 2H11/2/4S3/2–4I15/2 transitions via up- and down-conversion mechanisms, respectively. Therefore, up- and down-conversion dual-mode optical thermometry was achieved in one micro-sized thermometer, which allowed us to study the difference between the two methods. Two of the most important evaluating parameters for temperature sensors, e.g., the relative sensitivity and the temperature resolution, were studied and compared upon excitations at 980 and 405 nm. It was confirmed that no obvious difference was observed in these two cases. What’s more, it was demonstrated the 980 nm laser diode, compared with the 405 nm one, aroused more heat for the as-prepared samples. It may help us to select proper excitation sources in different situations. (paper)
[en] Er3+ and/or Yb3+ doped Sr2ScF7 up-conversion (UC) phosphors were synthesized, and the optimum doping concentrations of Yb3+ and Er3+ in the Sr2ScF7 host were found to be 20% mol and 7% mol, respectively. Under excitation of 980 nm laser, the UC spectra of the samples is composed of three green emission bands from 510 to 570 nm centered at 525, 543 and 551 nm and two red emission band from 640 to 690 nm with two peaks at 657 and 671 nm, which is attributed to the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. The UC emission color of Er3+ can be tuned by adjusting the intensity ratio of red to green emission through manipulating the population of red and green emitting states.
[en] A transparent and conducting ZnO:Er:Yb thin film with upconversion properties has been achieved after being annealed with continuous laser radiation just before the ablation point of the material. This work demonstrates that the laser energy preserves the conductivity of the film and at the same time creates an adequate surrounding for Er and Yb to produce visible upconversion at 660, 560, 520, and 480 nm under 980 nm laser excitation. The relation between the structural, electrical and upconversion properties is discussed. It is observed that the laser energy melts part of the material, which recrystallizes creating rare earth oxides and two different wurtzite structures, one with substitutional rare earths and oxygen vacancies (responsible for the conductivity) and the other without substitutional rare earth ions (responsible for the upconversion emission).
[en] A time-resolved (gated) luminescence-based method for the detection of some of N-acetyl amino acids, nucleobases, nucleotides, and DNA using terbium- 8-alkyl-2-oxo-2H-chromene-3-carbaldehyde (AOCC) complex in 1:2 metal: ligand ratio in microtiterplate format has been evolved. The linear range for determination of the selected biomolecules is 0.1–1.0 µM. The detection limit was in the range of 0.0371–0.106 µM. The thermodynamic parameters, and binding constants (K) of N-acetyl amino acids, nucleobases, nucleotides with Tb (III) –(AOCC) 2 complex were calculated. Positive and negative values of entropy (ΔS) and enthalpy (ΔH) changes for Tb (III) –(AOCC)2– N-acetyl amino acids, nucleobases or nucleotides ternary complexes were evaluated. Selectivity of Tb (III) -complex towards different biomolecules has been studied using ratiometric methods of analysis by comparison of biomolecules binding affinities for Tb (III) -complex. Interaction of Tb (III) complex with DNA has been studied.
[en] To validate the reliability of Judd-Ofelt results and the influence of involving absorption transition number, the Judd-Ofelt calculations, in which various transitions were adopted, were carried out for Tm3+ doped LiYF4 single crystal. It was found that introducing more transitions into the calculation procedure might get more reliable results. In order to clarify the feasibility of temperature self-reading in Tm3+/Yb3+ doped LiYF4 single crystal during laser operation, the temperature sensing properties of the single crystal were studied. It was found that the fluorescence intensity ratio of 3F2+3F3→3H6 to 3H4→3H6 can be used for achieving better temperature detection, and the temperature sensitivity was found much better than that in other materials.
[en] The kinetics of ytterbium ion electroluminescence was analyzed with the purpose of determining whether the main role in this process is played by donor-acceptor pairs of minority impurities. The investigations were performed with InP< Yb> samples. The electroluminescence was excited by current pulses at a 77 K sample temperature. The intracentral luminescence radiation intensity of the ytterbium ion was bound to increase following transmission of a Δt<=3.0 μs current pulse, attaining the maximum and then slowly dropping. Such an anomalous behaviour of the luminescence kinetics is characteristics of the excitation processes in which minority donor-acceptor pairs participate. The donor-acceptor pair lifetime (tau approximately 2 μs) as obtained by calculation and experimentally coinsides
[en] We report for the first time, to the best of our knowledge, the generation of a multi-watt optical vortex beam based on a novel monoclinic Yb3+-doped MgWO4 crystal. The robust first-order Laguerre–Gaussian doughnut beam (LG01) with high mode purity and good beam quality can be selectively excited without using any intra-cavity handedness-selective element. Our results demonstrate the potential of the Yb:MgWO4 crystal for generation of high-power optical vortex beams from compact solid-state lasers. (letter)
[en] Novel YOF:Er,Yb ceramic was successfully fabricated by vacuum hot-press sintering method for the first time, and its phase, microstructure and upconversion luminescence were investigated. It was found that the ceramic showed very dense microstructure with few pores. Under 980 nm excitation, strong green (526 nm and 546 nm) and red (668 nm) upconversion emissions of Er3+ ions in the ceramic were observed. The upconversion mechanism was proposed based on the power dependence of the upconverted emissions. In addition, the temperature sensing behavior of the YOF:Er,Yb ceramic was investigated from 293 K to 873 K by using the fluorescence intensity ratio technique, and the maximum absolute sensitivity is 0.00882 K−1 at 873 K and the maximum relative sensitivity is 1.35% K−1 at 293 K. These results indicate that the fabricated YOF:Er,Yb ceramic is promising host material for optical temperature sensors.
[en] Negative ions of Yb have been observed for the first time using high-resolution heavy-ion accelerator mass spectrometry to remove the intense molecular interfaces. The existence of stable negative ions of this element has been predicted recently. (author)