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[Display omitted] • Physicochemical properties of TPa = O, azafenidin and flumetsulam have been compared. • IR, Raman, UV–Vis and luminescence spectra have been analyzed. • The discussion has been based on DFT quantum chemical analysis. The herbicides azafenidin [(2-(2,4-dichloro-5-prop-2-ynoxyphenyl)-5,6,7,8-tetrahydro- [1,2,4] triazolo[4,3-a]pyridin-3-one)] and flumetsulam [(N-(2,6-difluorophenyl)-5-methyl- [1,2,4] triazolo[1,5-a]pyrimidine-2-sulfonamide)] were subjected to IR, Raman, UV–Vis and emission studies. As triazolopyridine is the most prominent and active component of these herbicides, this molecule was characterised by XRD studies, FTIR, Raman, UV–Vis and emission spectra. The experimental data were compared to the results of the DFT quantum chemical calculations carried out for its optimised structure, IR intensities and Raman activities, HOMO-LUMO transitions, and energies of the singlet and triplet states. The characteristics for triazolopyridine quantities were used in the analysis of the studied herbicides. [ABSTRACT FROM AUTHOR]

We have investigated the spectroscopic properties of Er3+-doped fluorotellurite glasses with the basic molar composition 75%TeO2-10%P2O5-10%ZnO-5%PbF2, modified by replacing 5% TeO2 by a metal oxide, namely WO3 or Nb2O5. The absorption edge of the glasses studied has been described within the Urbach approach, while the absorption and photoluminescence spectra have been analyzed in terms of the standard Judd-Ofelt theory, along with the photoluminescence decay of the 4I13/2 and 4S3/2 levels of the Er3+ ion. The absorption and emission spectra of the 4I15/2 ↔ 4I13/2 infrared transition have been analyzed within the McCumber theory to yield the peak emission cross-section and figure of merit for the amplifier gain. It appears that the fluorotellurite glass containing WO3 as a modifier is characterized by the largest figure of merit, indicating this matrix as a promising new host for doping with Er3+ ions. [ABSTRACT FROM AUTHOR]

• New methyl-nitropyridine thione and its thiol tautomer was synthesized. • Crystal structure was determined. • IR and Raman spectra were measured and analyzed using DFT approach. • Electron absorption and emission spectra were studied. • Depopulation mechanism of the electron excited states was proposed. Theoretical and experimental studies of new 4-methyl-3-nitropyridine-2-thione and its thiol tautomer were synthesized and characterized by means of structural and spectroscopic studies. X-ray diffraction, IR, Raman, UV–VIS and emission spectra were measured and analyzed. The quantum chemical DFT calculations were applied in the analysis of the obtained results. The effect of the temperature change on the structural and spectroscopic properties was studied. The vibrational characteristics and dynamical properties of the ϕ-S-H and ϕ= S type compounds are discussed where ϕ is a heterocyclic ring. The results of structural and spectroscopic studies were used to find a diagnostic tool on the structure of thione and tiol forms and their optic properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Tm-doped (Sc 0.5 Y 0.5 ) 2 SiO 5 (SYSO) crystals were grown by Czochralski method. The UV-VIR-NIR absorption spectra and the near-infrared emission spectra were measured and analysed by the Judd-Ofelt approach. Temperature influence on both absorption and emission spectra has been determined from the data recorded at room temperature and 10 K. It has been found that the structural disorder resulting from dissimilar ionic radii of Sc 3+ and Y 3+ in the solid solution (Sc 0.5 Y 0.5 ) 2 SiO 5 crystal brings about a strong inhomogeneous broadening of Tm 3+ ions spectra. However, it affects the excited state relaxation dynamics inherent to thulium-doped Y 2 SiO 5 and Sc 2 SiO 5 hosts weakly. [ABSTRACT FROM AUTHOR]

Temperature-dependent up-conversion luminescence spectra of Er 3+ in lead-free germanate glass have been examined under 800 nm and 980 nm diode laser excitation. Green up-conversion luminescence spectra measured in the 500–580 nm ranges correspond to transitions originating from thermally coupled 2 H 11/2 and 4 S 3/2 levels to 4 I 15/2 ground level of Er 3+ . The relative emission band intensities of 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ are changed with temperature. The rate of fluorescence intensity ratio varying with temperature was calculated for glass sample excited at 800 nm and 980 nm, respectively. The maximum temperature sensitivity is nearly 20% higher for glass sample pumped at 980 nm than 800 nm. [ABSTRACT FROM AUTHOR]

Green and red up-conversion luminescence spectra corresponding to 2 H 11/2 , 4 S 3/2 → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions of Er 3+ ions in Er 3+ /Yb 3+ co-doped lead-free fluorogermanate glasses have been examined as a function of Yb 3+ concentration and temperature. The green-to-red luminescence intensity ratio diminishes with increasing Yb 3+ concentration. The luminescence intensity ratio for bands related to the 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ was determined and temperature sensitivity parameters were calculated. The maximal temperature sensitivities for Er 3+ /Yb 3+ co-doped glass samples increase with increasing Yb 3+ concentration and the highest value of 42.5 × 10 −4 K −1 at room temperature was obtained for 0.5Er-3Yb system. Based on gathered data it was concluded that Er 3+ /Yb 3+ co-doped lead-free fluorogermanate glasses are promising for optical temperature sensing. [ABSTRACT FROM AUTHOR]

We have investigated the optical and spectroscopic properties of new Er 3+ -doped fluorotellurite glasses with the basic molar composition 75%TeO 2 -10%P 2 O 5 -10%ZnO-5%PbF 2 , modified by replacing 5%TeO 2 by four various metal oxides, namely MgO, PbO, SrO and CdO. The ellipsometric data have provided a Sellmeier-type dispersion relation of the refractive index of the investigated glasses. The optical absorption edge has been described within the Urbach approach, while the absorption and fluorescence spectra have been analyzed in terms of the standard Judd–Ofelt theory along with the photoluminescence decay of the 4 I 13/2 and 4 S 3/2 levels of the Er 3+ ion. The absorption and emission spectra of the 4 I 15/2 ↔ 4 I 13/2 infrared transition have been analyzed within the McCumber theory to yield the peak emission cross-section and figure of merit (FOM) for the amplifier gain. It appears that the glass containing MgO as a modifier is characterized by the largest FOM suggesting that the fluorotellurite matrix with this oxide can be a good novel host for Er 3+ ion doping. Finally, we propose a new simple method to calculate the mean transition energy of the McCumber approach as the arithmetic average of the barycenter wavenumbers of absorption and emission spectra. [ABSTRACT FROM AUTHOR]

GdAl 3 (BO 3) 4 (GAB) compound doped with Tb3+ and Eu3+ was synthetized. The excited states of these lanthanide ions were analyzed up to VUV range 125 000 cm-1 (80 nm). VUV multiplets of Tb3+ and Eu3+ has been determined. The Eg has been estimated to be 7.15 eV and it was assigned to the O 2p → B 2p, 2s transitions within the isolated BO3− groups. The strong and effective coupling between terbium and europium was observed and examined. The efficient impact of temperature on inter-ionic energy transfer was found and examined. The yields of energy transfer (η) at room temperature were determined to be: ca. 20% and 60% for GAB: 20 at.%Tb, 3 at.%Eu and GAB: 20 at.%Tb, 20 at.%Eu, respectively. When the europium 5D 0 multiplet is excited via terbium multiplets, the decay curve becomes non-exponential with build-up part maximum situated at ca. 0.7 ms after initial pulses. Based on the low- and room temperature excitation and luminescence spectra, experimental free-ion levels, located between 0 and 35 000 cm-1, were determined and used for the free-ion analysis. [Display omitted] • Novel terbium-europium crystal has been synthesized. • Addition of Eu changes the symmetry. • The positions of 4f and 5d states have been determined. • Energy transfer processes and quenching mechanism have been appointed. • The influence of temperature on the energy transfer has been given. [ABSTRACT FROM AUTHOR]

Spectroscopic features and laser performance of a novel thulium-doped scandium yttrium silicate crystal Tm 3+ :ScYSiO 5 (Tm:SYSO) are presented. The experimental lifetime of luminescence related to the 3 F 4 – 3 H 6 laser transition of Tm 3+ amounts to 1.1 ms, which is smaller by a factor of three than the calculated radiative lifetime value due to the contribution of nonradiative relaxation. As a consequence of the internal disordered structure of the SYSO host crystal, the luminescence bands of 3 F 4 – 3 H 6 and 3 H 4 - 3 H 6 show significant inhomogeneous spectral broadening as compared with that of SSO. The laser performances were evaluated in an end-pumped cavity using a CW semiconductor laser as a pump source. In a free run regime, the Tm:SYSO laser delivered a maximum output power of 580 mW at 2022 nm, corresponding to a slope efficiency of 17.4%. With a birefringent quartz plate inserted into laser cavity, the laser output wavelength was continuously tuned from 1950 nm to 2057 nm and dual wavelength operations at 2011 nm and 2020 nm, 1987 nm and 2045 nm, 2022 nm and 2044 nm were observed. [ABSTRACT FROM AUTHOR]

Among a wide variety of solid state materials lanthanide beta-diketonates, their derivatives and polymeric materials based on them have become essential for advance technologies. Thus they are the subject of extensive spectroscopic studies. Using appropriate lanthanide chelates for the emission layer one can achieve electroluminescence covering the spectrum from blue to infrared. Moreover, compounds with proper chromophores can be the best way to excite and enhance the emission although the f-f transitions have forbidden character. Two types of new Sm(III) chelates; phosphoro and sulfono-derivatives of beta-diketones and polymeric materials on their base were obtained and characterized by the high resolution photoluminescence spectroscopy at 293, 77 and 4 K, as well as by luminescence decay times. Those new type of phosphors shows strong orange emission after excitation at 404 nm Sm(III) states and 280 nm ligand bands. Radiative transition probabilities were calculated from absorption spectra and Judd- Ofelt parameters evaluated. Effects of the temperature, rigidity of polymeric lattice and the energy of excitation on intensities of the Sm(III) fluorescence were studied. The paths of energy transfer are analysed and mechanism of this process is proposed. [ABSTRACT FROM AUTHOR]

The Ca,Eu-α-sialon powders with the mixed solid solution composition have been manufactured via the solid-state reaction process in flowing nitrogen in a graphite furnace at a relatively low temperature of 1650 °C without an external overpressure. XRD data with Rielveld refinement and XPS measurements were used for characterization of the lattice constants and the surface chemical composition. The monophase Ca-Eu-α-sialon was obtained with the nominal composition of Eu 0.048 Ca 0.702 Si 7.75 Al 2.25 O 0.75 N 15.25 . The highest emission intensity in a yellow-orange region at 590 nm and quantum efficiency of 66% was found for this pure Ca,Eu-α-sialon. Estimation of m,n values from the lattice constant and EDS results showed a small deviation from the nominal composition of designed α-sialon. XPS results demonstrated significant changes of the chemical composition in the oxidized surface of phosphor particles. Possible reasons of emission redshift and relationship between the actual solid solution composition and luminescence properties are discussed in terms of simultaneous presence of Eu 2+ and Eu 3+ ions in the sialon crystal lattice and residual oxynitride glass. [ABSTRACT FROM AUTHOR]

Detailed spectroscopic investigation of YVO 4 :5 at% Eu 3+ , 1 at % Tm 3+ single crystal encompassing analysis of absorption, excitation and time resolved emission spectra recorded at 5 K and 300 K made it possible to determine energies, intensities and bandwidths of transitions within 4f n configurations of trivalent thulium and europium. Transients recorded upon femtosecond pulse excitation made it possible to determine dynamics of population build-up and relaxation of excited states involved in luminescence phenomena. It was found that in YVO 4 :Eu, Tm system the metastable 5 D 0 level of Eu 3+ and 1 G 4 level of Tm 3+ can be populated by energy transfer from excited VO 4 3− group and respective intra-ion relaxation processes from higher energy levels. Recorded excitation spectra of the 5 D 0 luminescence of Eu 3+ and of the 1 G 4 luminescence of Tm 3+ do not evidence the Eu 3+ ↔Tm 3+ energy transfer. Nevertheless, an examination of acquired luminescence decay curves, performed with reference to available information on relaxation dynamics of YVO 4 :Tm 3+ system, reveals that the incorporation of Eu 3+ accelerates decays of the 1 G 4 and 3 H 4 levels of Tm 3+ . Spectroscopic parameters characterising the donor–acceptor interaction involved in the 3 H 4 decay were evaluated applying the Inokuti–Hirayama model. Relevance of donor and acceptor transition peculiarities for energy transfer processes contributing to the 1 G 4 and 3 H 4 decays was assessed in the framework of phenomenological model proposed by Kushida and discussed. It was concluded that the intensity ratio of the blue 1 G 4 luminescence to orange–red 5 D 0 luminescence; hence the colour of visible emission in UV-excited YVO 4 :Eu 3+ , Tm 3+ phosphor, may be adjusted by appropriate choice of Eu 3+ and Tm 3+ concentrations. [ABSTRACT FROM AUTHOR]

Thermal, structural and optical properties of lead phosphate glasses containing Er 3+ ions have been studied as a function of PbF 2 concentration. Incorporation of PbF 2 results in structural and spectroscopic changes around Er 3+ ions and surrounding ligands, which were analyzed in detail using by DSC, XRD, absorption and luminescence spectroscopy. Especially, near-infrared luminescence spectra due to main 4 I 13/2 - 4 I 15/2 laser transition of Er 3+ ions are presented and discussed with PbF 2 content. Based on decay curve measurements the 4 I 13/2 luminescence lifetime of Er 3+ was determined and its value is found to be maximum at 18 mol% of PbF 2 . [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of Pb-containing glasses of high optical quality and chemical purity are obtained. • XRD, IR transmission, UV-Vis absorption & photoluminescence of obtained glasses are studied. • Intrinsic photoluminescence broad bands in the visible range were discovered and analysed. • Fast and slow recombination mechanisms for intrinsic photoluminescence bands were proposed. • The studied glasses are perspective luminescent materials of the visible spectral range. The X-ray diffraction, infrared transmission, optical absorption, photoluminescence spectra and decay kinetics of a series of un-doped Pb-containing glasses with compositions of 0.4PbO–0.6GeO 2 , 0.6PbO–0.4SiO 2 , 0.7PbO–0.3B 2 O 3 , and 0.54PbO–0.34B 2 O 3 –0.12GeO 2 were studied. Average interatomic distances and coordination numbers for main structural units GeO 4 , SiO 4 , BO 4 , BO 3 , and PbO n (n = 3 – 6) in all studied glasses were derived from radial distribution functions. The 0.4PbO–0.6GeO 2 and 0.54PbO–0.34B 2 O 3 –0.12GeO 2 glasses upon UV photoexcitation show intense broad emission bands with maxima at 478 and 543 nm, respectively, and weaker broad band with peak about 610 nm. Based on luminescence decay kinetics analysis were proposed fast (band-to-band recombination) and slow (recombination with participation of point defects) mechanisms of intrinsic luminescence in the 0.4PbO–0.6GeO 2 and 0.54PbO–0.34B 2 O 3 –0.12GeO 2 glasses. The 0.6PbO–0.4SiO 2 and 0.7PbO–0.3B 2 O 3 glasses under UV – violet photoexcitation reveal only broad emission band with a maximum at 599 and 593 nm, respectively, caused by the band-to-band fast recombination mechanism. [ABSTRACT FROM AUTHOR]

Highlights: [•] Transformation of femtosecond pulses in laser crystals. [•] Generation of supercontinuum in selected single crystals. [•] Effect of material bandgap on the supercontinuum generation. [Copyright &y& Elsevier]

Abstract: Illumination of single crystal samples of erbium-doped YVO4 and LuVO4 by infrared femtosecond pulses brings about an intense green luminescence assigned to the 4S3/2 - 4I15/2 transition of Er3+ ions. When lowering the sample temperature an additional broad band in the blue related to the VO4 3− emission appears and next grows steadily. It has been observed that the variation of wavelength of incident infrared femtosecond pulses in the region 800nm–1600nm affects weakly the intensity of both the blue and green luminescence bands. Analysis of luminescence dynamics made it possible to reveal that upon infrared excitation the rise time of the 4S3/2 luminescence is longer by a factor of four, roughly as compared to that recorded upon direct excitation into high energy levels of Er3+. Observed temperature dependence of up-converted blue and green luminescence implies that the energy transfer from vanadate groups cannot be considered as a main mechanism involved in the excitation erbium ions. It has been supposed that erbium ions are likely to be excited by energy transfer from free electrons created in the conduction band of the host by multiphoton excitation and /or by non-resonant multi-step ETU process involving absorption of infrared light in multiphonon side bands of electronic transitions. Creation of free electrons has been corroborated by changes of electrical conductivity of crystals induced by an illumination with infrared femtosecond pulses. [Copyright &y& Elsevier]

Abstract: The (Lu x Gd0.995−x Sm0.005)2SiO5 single crystals with x=0.095, 0.11, 0.15, 0.17, 0.19 0.35 and 0.5 were grown by the Czochralski method. Structural properties were investigated by X-ray diffraction measurements. Unit cell parameters and cell volume were determined by the Rietveld refinement of the collected X-ray powder spectra. The segregation features between Gd and Lu were estimated and analyzed. Vibrational properties of the solid solutions were analyzed on the basis of polarized Raman spectra acquired at 300–875K temperature range. Absorption and emission spectra of Sm3+ ion in the crystals with different composition were analyzed in the terms of dopant energy levels, oscillator strengths of transitions and spectral features of luminescence bands in the visible range. Both structural and optical investigations revealed that change of Lu3+ content in (Lu x Gd0.995−x Sm0.005)2SiO5 solid solution crystals induces the phase transition from C2/c (Lu2SiO5) to P21/c (Gd2SiO5) structure. It was found that the break of LSO to GSO-type structure occurs at 0.15

Abstract: Selected heavy metal glasses containing Yb3+ and Er3+ ions have been studied. Near-infrared luminescence spectra at 1.53μm and up-conversion spectra of Er3+ ions were registered under excitation of Yb3+ ions by 975nm diode laser line. The luminescence bands correspond to 4I13/2–4I15/2 (NIR), 4S3/2–4I15/2 (green) and 4F9/2–4I15/2 (red) transitions of Er3+, respectively. The optical transitions of rare earth ions have been examined as a function of glass host. The unusual large spectral linewidth nearly close to 110nm for 4I13/2–4I15/2 transition of Er3+ ions in Yb–Er co-doped lead borate glass was obtained, whereas long-lived NIR luminescence at 1.53μm was detected in lead germanate glass. The NIR luminescence and up-conversion phenomena strongly depend on stretching vibrations of glass host, which was confirmed by FT-IR spectroscopy. [Copyright &y& Elsevier]

A new neodymium [Nd(BCPN) 3 (NO 3) 3 (H 2 O) 2 complex with 3-bromo-2-chloro-6-picolinic N-oxide was synthesized and characterized by means of spectroscopic studies and DFT quantum chemical calculations. The IR, Raman, electron UV-VIS and emission spectra measurements were performed. The femtosecond excitation was used to establish an excited energy level depopulation mechanism. The influence of the halo-groups position on the structural and optical properties of the studied compound was discussed. Ligand-to-metal energy transfer in the studied neodymium complex was analysed. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this work, spectroscopic properties of (Lu 0.25 Gd 0.75) 2(1-x) Tm 2x SiO 5 (x = 0.04 and 0.005) single crystals were investigated. The material was found to be biaxial, exhibiting strong optical anisotropy, as clearly demonstrated in polarized absorption and emission spectra. Data from room temperature polarized absorption spectra were used in calculations within the phenomenological Judd-Ofelt model. The intensity parameters Ω t were established at Ω 2 = 3.24 (±0.58), Ω 4 = 2.96 (±0.24) and Ω 6 = 0.86 (±0.14) [10−20 cm2]. The values of fluorescence lifetimes of the 1D 2 and 1G 4 levels were measured and subsequently compared with those calculated using the Judd-Ofelt theory. The strong absorption bands located at wavelengths around 355, 460 and 790 nm, related to the 3H 6 → 1D 2 , 1G 4 , 3H 4 transitions, were found suitable for optical pumping of the investigated material. The characteristics of emission spectra recorded in the blue (ca. 455 nm) and IR (ca. 1750 nm) regions indicate that further investigations of stimulated emission within those wavelength ranges are well justified and can be considered promising. • Spectroscopic investigations of Tm doped (Lu 0.25 Gd 0.75) 2 SiO 5 single crystals were conducted. • Material shows high potential for lasing in IR region ca. 1900 nm. • Influence of Anisotropy and temperature on spectroscopic properties is reported. [ABSTRACT FROM AUTHOR]

The thermal stability of oxyfluorotellurite glass systems, (65-x)TeO 2 -20ZnF 2 -12PbO-3Nb 2 O 5 -xPr 2 O 3 , doped with praseodymium was examined. The different concentrations of praseodymium oxide (x = 0.5 and 2 mol%) were applied to verify the thermal, optical and luminescence properties of the materials under study. The relatively high values of the Dietzel (ΔT) and Saad-Poulain (S or H') thermal stability factors determined using a differential thermal analysis (DTA) indicate the good thermal stability of the glass matrix, which gradually improves with the content of the active dopant. The temperature dependence of optical spectra in the temperature range 300-675 K for the VIS-NIR region was investigated. The involved Pr 3+ optical transition intensities and relaxation dynamic of the praseodymium luminescent level were determined. The ultrashort femtosecond pulses were utilized to examine a dynamic relaxation of the praseodymium luminescent levels. Although the measured emission of the Pr 3+ active ions in the studied glass encompasses the quite broad spectral region, the observed luminescence may only be attributed to 3 P J excited states. As a result, the observed decrease in the experimental lifetime for the 3 P 0 level along with the increasing activator content was identified as an intensification of the Pr-Pr interplay and the associated self-quenching process. The maximum relative sensitivities (S r ) estimated over a relatively wide temperature range are ~0.46% K -1 (at 300 K) for FIR (I 530 /I 497 ) and 0.20% K -1 (at 600 K) for FIR (I 630 /I 497 ), which seems to confirm the possibility of using investigated glasses in optical temperature sensors.

The recent COVID-19 pandemic has made everyone aware of the threat of viruses and the growing number of antibiotic-resistant bacteria. It has become necessary to find new methods to combat these hazards. One tool that could be used is UVC radiation, i.e., 100-280 nm. Currently, the available sources of this light are mercury vapor lamps. However, the modern world requires more compact, mercury-free, and less energy-consuming light sources. This work presents the results of our research on a new material in which efficient UVC radiation was obtained. Here, we present the results of research on Ca 9 Y(PO 4 ) 7 polycrystals doped with Pr 3+ ions prepared using the solid-state method. The absorption, excitation, emission, and emission decay profiles of praseodymium(III) ions were measured and analyzed. The upconversion emission in the UVC region excited by blue light was observed. Parameters such as energy bandgap, refractive index, and thermal stability of luminescence were determined. The studied phosphate-based phosphor possesses promising characteristics that show its potential in luminescent applications in future use in medicine or for surface disinfection.

The application of ultraviolet-C light in the field of surface treatment or photodynamic therapy is highly prospective. In this regard, the stable fluorescent silicate SrO-CaO-MgO-SiO 2 -Pr 2 O 3 glasses able to effectively convert visible excitation on the ultraviolet praseodymium emission were fabricated and examined. An unusual wide-range visible-to-UVC up-conversion within 240-410 nm has been achieved in Pr 3+ -doped glasses, revealing their potential advantage in different sophisticated disinfection technologies. The integrated emission intensity was studied as a function of light excitation power to assess a mechanism attributed to UVC luminescence. Especially, it was revealed that the multicomponent silicate glass qualities and praseodymium 3 P J excited state peculiarities are favorable to obtaining useful broadband ultraviolet up-converted luminescence. The glass dispersion qualities were determined between 450-2300 nm. The impact of praseodymium concentration on Vis-NIR spectroscopic glass qualities was evaluated employing absorption spectra, emission spectra, and decay curves of luminescence associated with two involved praseodymium excited states. Especially, efficient interionic interactions can be inferred by investigating the decrease in 1 D 2 state experimental lifetime in the heavily doped samples. Examination of absorption spectra as a function of temperature implied that excitation at 445 nm should be quite effective up to T = 625 K. Contrary to this, temperature elevation gives rise to a moderate lowering of the visible praseodymium luminescence.

Fluorides have a wide bandgap and therefore, when doped with the appropriate ions, exhibit emissions in the ultraviolet C (UVC) region. Some of them can emit two photons in the visible region for one excitation photon, having a quantum efficiency greater than 100%. In a novel exploration, praseodymium (Pr 3+ ) ions were introduced into KLaF 4 crystals for the first time. The samples were obtained according to a high-temperature solid-state reaction. They exhibited an orthorhombic crystal structure, which has not been observed for this lattice yet. The optical properties of the material were investigated in the ultraviolet (UV) and visible ranges. The spectroscopic results were used to analyze the Pr 3+ electronic-level structure, including the 4 f 5 d configuration. It has been found that KLaF 4 :Pr 3+ crystals exhibit intense luminescence in the UVC range, corresponding to multiple 4 f → 4 f transitions. Additionally, under vacuum ultraviolet (VUV) excitation, distinct transitions, specifically 1 S 0 → 1 I 6 and 3 P 0 → 3 H 4 , were observed, which signifies the occurrence of photon cascade emission (PCE). The thermal behavior of the luminescence and the thermometric performance of the material were also analyzed. This study not only sheds light on the optical behavior of Pr 3+ ions within a KLaF 4 lattice but also highlights its potential for efficient photon management and quantum-based technologies.

A new methyl-dinitro-phenylhydrazinyl-pyridine derivative [2-methyl-3,5-dinitro-6-(2-phenylhydrazinyl)pyridine] was synthesised and characterised by means of structural and spectroscopic measurements. The X-ray diffraction studies revealed that the compound crystallises in the centrosymmetric monoclinic space group P2 1 /n, with two symmetry-independent molecules in the asymmetric unit with Z = 8. Hydrazo bridge C-NH-NH-C links two fragments composed of phenyl ring and pyridine unit substituted with methyl and nitro groups. Such a structure was confirmed by 1 H and 13 C NMR studies as well as IR, Raman, UV-Vis, and emission spectra. The results were analysed using the quantum-chemical DFT calculations. The paper reports the vibrational characteristics and discusses dynamical properties of this moiety. The full set of the normal modes typical of the hydrazo bridge was identified and assigned to respective IR and Raman bands. The results of structural and spectroscopic studies were used to find the dependence between the conformation of the θ-NH-NH-ϕ system and its optic properties. The experimental UV-Vis and emission spectra were discussed in terms of the calculated singlet and triplet states that allowed assigning the unique spectral pattern originating from the electrons of the hydrazo-bridge system., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Membranes produced by crosslinking chitosan with magnesium phytate were prepared using highly deacetylated chitosan and its N -carboxymethyl, O -carboxymethyl and N , O -carboxymethyl derivatives. The conditions of the membrane production were described. IR, Raman, electron absorption and emission spectra were measured and analyzed for all the substrates. It was found that O -carboxymethyl chitosan derivative is the most effectively crosslinked by magnesium phytate, and the films formed on this substrate exhibit good mechanical parameters of strength, resistance and stability. Strong O-H···O hydrogen bonds proved to be responsible for an effective crosslinking process. Newly discovered membrane types produced from chitosan and magnesium phytate were characterized as morphologically homogenous and uniform by scanning electron microscopy (SEM) and IR measurements. Due to their good covering properties, they do not have pores or channels and are proposed as packaging materials.

The shielding and spectroscopic properties of Pr +3 and Pr 3+ /Ho 3+ -codoped tellurite glass were investigated. The intensity parameters (Ω2 = 3.24-, Ω4 = 1.64-, Ω6 = 1.10 × 10 -20 cm 2 ) as well as the radiative lifetimes of 3 F 4 + 5 S 2 and 5 I 6 excited states of Ho 3+ ions were equal to 301 μs and 3.0 μs, respectively. The former value appears to be much higher than that obtained from the lifetime measurement, indicating the presence of various energy transfer processes. The NIR spectrum of Pr 3+ /Ho 3+ -co-doped tellurite glass is dominated by strong Ho 3+ : 5 I 6 emission at around 1200 nm, being the result of the energy transfer from Pr 3+ to Ho 3+ ions. The shielding effectiveness of the prepared glasses showed good performance against high-energy photons. These findings suggest that the prepared glasses could be used in laser technology such as photodynamic therapy (PDT) treatment procedures and as shielding for radiation protection.

Novel ternary fluoro-germano-tellurite (GTS) glasses doped with Er 3+ ions with 0.5 mol% and 1.0 mol% were fabricated by a conventional melt and quenching method and investigated using methods of optical spectroscopy. The room-temperature absorption spectrum was recorded and analyzed to determine radiative transition rates, radiative lifetimes, and branching ratios of Er 3+ luminescence. Decay curves of Er 3+ luminesccence were recorded and analyzed. Temperature dependences of emission spectra and absorption spectra in the region from RT (room-temperature) up to 675 K were studied in detail. The contribution of competing radiative and nonradiative processes to the relaxation of luminescent levels of Er 3+ was assessed. Absolute and relative sensitivity were established utilizing the comprehensive model based on thermally coupled 2 H 11/2 / 4 S 3/2 excited states of erbium. The high quantum efficiency of the first erbium-excited state and value of gain coefficient indicate that GTS:Er glass system can be considered as conceivable NIR (near infrared) laser material as well.

Thermal control of liquids with high (micrometric) spatial resolution is required for advanced research such as single molecule/cell studies (where temperature is a key factor) or for the development of advanced microfluidic devices (based on the creation of thermal gradients at the microscale). Local and remote heating of liquids is easily achieved by focusing a laser beam with wavelength adjusted to absorption bands of the liquid medium or of the embedded colloidal absorbers. The opposite effect, that is highly localized cooling, is much more difficult to achieve. It requires the use of a refrigerating micro-/nanoparticle which should overcome the intrinsic liquid heating. Remote monitoring of such localized cooling, typically of a few degrees, is even more challenging. In this work, a solution to both problems is provided. Remote cooling in D 2 O is achieved via anti-Stokes emission by using an optically driven ytterbium-doped NaYF 4 microparticle. Simultaneously, the magnitude of cooling is determined by mechanical thermometry based on the analysis of the spinning dynamics of the same NaYF 4 microparticle. The angular deceleration of the NaYF 4 particle, caused by the cooling-induced increase of medium viscosity, reveals liquid refrigeration by over -6 K below ambient conditions., (© 2021 The Authors. Small published by Wiley-VCH GmbH.)

Peritoneal dissemination is a common consequence of a relapse following a radical surgical treatment of gastric cancer. The development of the disease in the peritoneum depends not only on its stage, but also on free cancer cells exfoliated from the tumor mass or from involved lymph nodes, and which are capable of being implanted in the peritoneum. According to the latest TNM (7 edition; 2010) classification, patients with free cancer cells in the peritoneal washings qualify for stage IV of the disease. Patients in whom free cancer cells were found during the operation - have a recurrence of gastric cancer - mainly in the peritoneum, and the majority of them die within two years of the diagnosis. To properly assess the prognosis, it is vital to determine the stage of cancer by additionally assessing the washings for the presence of free cancer cells before taking a therapeutic decision. This also allows identifying those patients who require different medical procedures to obtain the best treatment results possible. Medical literature describes various methods of examining peritoneal washings aimed at detecting free cancer cells. The methods apply different cancer cell detection rates, sensitivity and specificity in prediction of a peritoneal relapse. Oncological Departments performing the evaluation of the washings employ non-standard methods of treatment in this group of patients and the results presented are promising.

Unlabelled: Presence of free gastric cancer cells in the peritoneal cavity of patients who underwent surgical treatment for gastric cancer is a negative prognostic factor and caused rapid disease recurrence, manifested as peritoneal metastases. Positive peritoneal cytology despite lack of visible peritoneal metastases was regarded as M1 class in the TNM classification (7th edition) in 2010. The aim of the study was to analyze factors associated with positive peritoneal cytology and identify groups of patients in whom diagnostic laparoscopy plus peritoneal lavage in the diagnostic process could affect therapeutic decisions., Material and Methods: The study enrolled patients with gastric cancer who underwent surgical treatment at the Department of Surgery, Wielkopolskie Oncology Center in Poznań. During the laparotomy, after opening of the peritoneal cavity, 200 ml of physiological saline at 37 °C was administered in the tumor region. After this fluid was mixed, 100 ml of lavage fluid was collected. This fluid was subsequently spun many times to obtain sediment for cytology and immunohistochemistry investigation using anti-BerEp-4, CK 7/20, and B72.3. Results of peritoneal cytology were analyzed jointly with clinical factors--patient's age, sex and pathology factors--tumor invasion, involvement of lymph nodes, histological grade, histological type according to Lauren and localization of the cancer in the stomach., Results: Analysis of the peritoneal fluid for presence of free cancer cells was done in 51 patients. Positive peritoneal cytology was found in 12 (23.5%) patients. In the group of patients with positive cytology, all patients had T3/T4 tumors and all were found to have lymph node metastases, while G3 cancer was found in 83.3% of patients. In patients with positive cytology, diffuse gastric cancer according to Lauren predominated (9 of 12 patients, 75%), while in patients with negative cytology--intestinal type (20 of 39 patients, 51.2%). In the group of patients with positive histology, the whole stomach was involved by the cancer process in 7 of 12 patients (58.3%), while in the group with negative histology, in 29 of 39 patients the tumor was located in the gastric body and prepyloric part (74.4%)., Conclusions: Based on this study we can conclude that determinants of positive peritoneal cytology include: tumor stage T3/T4, N+, G3, cancer located in the whole stomach, diffuse histological type according to Lauren.