Imaging Extreme Ultraviolet Radiation Using Nanodiamonds with Nitrogen-Vacancy Centers

Extreme ultraviolet (EUV) radiation with wavelengths of 10–121 nm has drawn considerable attention recently for its use in photolithography to fabricate nanoelectronic chips. This study demonstrates, for the first time, fluorescent nanodiamonds (FNDs) with nitrogen-vacancy (NV) centers as scintillators to image and characterize EUV radiations. The FNDs employed are ∼100 nm in size; they form a uniform and stable thin film on an indium–tin–oxide-coated slide by electrospray deposition. The film is nonhygroscopic and photostable and can emit bright red fluorescence from NV0 centers when excited by EUV light. An FND-based imaging device has been developed and applied for beam diagnostics of 50 nm and 13.5 nm synchrotron radiations, achieving a spatial resolution of 30 μm using a film of ∼1 μm thickness. The noise equivalent power density is 29 μW/(cm2 Hz1/2) for the 13.5 nm radiation. The method is generally applicable to imaging EUV radiation from different sources

Controlling The Activator Site To Tune Europium Valence in Oxyfluoride Phosphors

A new Eu³⁺-activated oxyfluoride phosphor Ca₁₂Al₁₄O₃₂F₂:Eu³⁺ (CAOF:Eu³⁺) was synthesized by a solid state reaction. Commonly red line emission was detected in the range of 570–700 nm. To achieve the requirement of illumination, this study revealed a crystal chemistry approach to reduce Eu ions from 3+ to 2+ in the lattice. Replacing Al³⁺–F^– by the appreciate dopant Si⁴⁺–O^2– is adopted to enlarge the activator site that enables Eu³⁺ to be reduced. The crystallization of samples was examined by powder X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Photoluminescence results indicated that as-synthesized phosphors Ca₁₂Al_{14‑<i>z</i>}Si_<i>z</i>O_32+<i>z</i>F_2–<i>z</i>:Eu (<i>z</i> = 0–0.5, CASOF:Eu) display an intense blue emission peaking at 440 nm that was produced by 4f–5d transition of Eu²⁺, along with the intrinsic emission of Eu³⁺ under UV excitation. Moreover, the effect of Si⁴⁺–O^2– substitution involved in the coordination environment of the activator site was investigated by further crystallographic data from Rietveld refinements. The ¹⁹F solid-state nuclear magnetic resonance (NMR) data were in agreement with refinement and photoluminescence results. Furthermore, the valence states of Eu in the samples were analyzed with the X-ray absorption near edge structure (XANES). The quantity of substituted Si⁴⁺–O^2– tunes chromaticity coordinates of Ca₁₂Al_{14–<i>z</i>}Si_<i>z</i>O_32+<i>z</i>F_2–<i>z</i>:Eu phosphors from (0.6101, 0.3513) for <i>z</i> = 0 to (0.1629, 0.0649) for <i>z</i> = 0.5, suggesting the potential for developing phosphors for white light emitting diodes (WLEDs). Using an activator that is valence tunable by controlling the size of the activator site represents a hitherto unreported structural motif for designing phosphors in phosphor converted light emitting diodes (pc-LEDs)

All-In-One Light-Tunable Borated Phosphors with Chemical and Luminescence Dynamical Control Resolution

Single-composition white-emitting phosphors with superior intrinsic properties upon excitation by ultraviolet light-emitting diodes are important constituents of next-generation light sources. Borate-based phosphors, such as NaSrBO₃:Ce³⁺ and NaCaBO₃:Ce³⁺, have stronger absorptions in the near-ultraviolet region as well as better chemical/physical stability than oxides. Energy transfer effects from sensitizer to activator caused by rare-earth ions are mainly found in the obtained photoluminescence spectra and lifetime. The interactive mechanisms of multiple dopants are ambiguous in most cases. We adjust the doping concentration in NaSrBO₃:RE (RE = Ce³⁺, Tb³⁺, Mn²⁺) to study the energy transfer effects of Ce³⁺ to Tb³⁺ and Mn²⁺ by comparing the experimental data and theoretical calculation. The vacuum-ultraviolet experimental determination of the electronic energy levels for Ce³⁺ and Tb³⁺ in the borate host regarding the 4f–5d and 4f–4f configurations are described. Evaluation of the Ce³⁺/Mn²⁺ intensity ratios as a function of Mn²⁺ concentration is based on the analysis of the luminescence dynamical process and fluorescence lifetime measurements. The results closely agree with those directly obtained from the emission spectra. Density functional calculations are performed using the generalized gradient approximation plus an on-site Coulombic interaction correction scheme to investigate the forbidden mechanism of interatomic energy transfer between the NaSrBO₃:Ce³⁺ and NaSrBO₃:Eu²⁺ systems. Results indicate that the NaSrBO₃:Ce³⁺, Tb³⁺, and Mn²⁺ phosphors can be used as a novel white-emitting component of UV radiation-excited devices

Infrared and Ultraviolet Spectra of Diborane(6): B₂H₆ and B₂D₆

We recorded absorption spectra of diborane(6), B₂H₆ and B₂D₆, dispersed in solid neon near 4 K in both mid-infrared and ultraviolet regions. For gaseous B₂H₆ from 105 to 300 nm, we report quantitative absolute cross sections; for solid B₂H₆ and for B₂H₆ dispersed in solid neon, we measured ultraviolet absorbance with relative intensities over a wide range. To assign the mid-infrared spectra to specific isotopic variants, we applied the abundance of ¹¹B and ¹⁰B in natural proportions; we undertook quantum-chemical calculations of wavenumbers associated with anharmonic vibrational modes and the intensities of the harmonic vibrational modes. To aid an interpretation of the ultraviolet spectra, we calculated the energies of electronically excited singlet and triplet states and oscillator strengths for electronic transitions from the electronic ground state

Identification of <i>cyc</i>-B₃H₃ with Three Bridging B–H–B Bonds in a Six-Membered Ring

Irradiation of samples of diborane(6), B₂H₆ and B₂D₆, separately and together, dispersed in solid neon near 4 K with tunable far-ultraviolet light from a synchrotron yielded new infrared absorption lines that are assigned to several carriers. Besides H, B, BH, BH₂, BH₃, B₂, B₂H₂, and B₂H₄, previously identified, a further species is assigned on the basis of quantum-chemical calculations of vibrational wavenumbers and intensities to be <i>cyc</i>-B₃H₃ (<i>D</i>_3<i>h</i>, singlet state) in several isotopic variants, which feature three bridging B–H–B bonds in a six-membered ring

Facile Atmospheric Pressure Synthesis of High Thermal Stability and Narrow-Band Red-Emitting SrLiAl₃N₄:Eu²⁺ Phosphor for High Color Rendering Index White Light-Emitting Diodes

Red phosphors (e.g., SrLiAl₃N₄:Eu²⁺) with high thermal stability and narrow-band properties are urgently explored to meet the next-generation high-power white light-emitting diodes (LEDs). However, to date, synthesis of such phosphors remains an arduous task. Herein, we report, for the first time, a facile method to synthesize SrLiAl₃N₄:Eu²⁺ through Sr₃N₂, Li₃N, Al, and EuN under atmospheric pressure. The as-synthesized narrow-band red-emitting phosphor exhibits excellent thermal stability, including small chromaticity shift and low thermal quenching. Intriguingly, the title phosphor shows an anomalous increase in theoretical lumen equivalent with the increase of temperature as a result of blue shift and band broadening of the emission band, which is crucial for high-power white LEDs. Utilizing the title phosphor, commercial YAG:Ce³⁺, and InGaN-based blue LED chip, a proof-of-concept warm white LEDs with a color rendering index (CRI) of 91.1 and R9 = 68 is achieved. Therefore, our results highlight that this method, which is based on atmospheric pressure synthesis, may open a new means to explore narrow-band-emitting nitride phosphor. In addition, the underlying requirements to design Eu²⁺-doped narrow-band-emitting phosphors were also summarized

High Color Rendering Index of Rb₂GeF₆:Mn⁴⁺ for Light-Emitting Diodes

High Color Rendering Index of Rb₂GeF₆:Mn⁴⁺ for Light-Emitting Diode

Enhance Color Rendering Index via Full Spectrum Employing the Important Key of Cyan Phosphor

A new concept called “full-spectrum lighting” has attracted considerable attention in recent years. Traditional devices are usually combined with ultraviolet–light-emitting diode (LED), red, green, and blue phosphors. However, a cyan cavity exists in the 480–520 nm region. Hence, cyan phosphors are needed to compensate for the cavity. (Sr,Ba)₅(PO₄)₃Cl:Eu²⁺ phosphors feature an extremely unique and tunable photoluminescence spectrum. Nevertheless, the tuning mechanisms of these phosphors remain unclear. In this study, we elucidate the mechanism of the cation size-controlled activator uneven-occupation and reoxidation in (Sr,Ba)₅(PO₄)₃Cl:Eu²⁺ phosphors. This mechanism could help tune the optical properties of related apatite families and structures with multiple cation sites and strongly uneven occupation of activators and cations. Finally, the package of the LED device is constructed to show that both color rendering index Ra and R9 are higher than 95. Thus, the device could be a potential candidate for full-spectrum lighting