VUV spectroscopy of Ce<Superscript>3+</Superscript>-doped Na<Subscript>0.4</Subscript>Lu<Subscript>0.6</Subscript>F<Subscript>2.2</Subscript> single crystals

The short-wave transmission spectrum of Na_0.4Lu_0.6F_2.2 with the visible/ultraviolet transmission edge of 8 eV was studied. Absorption spectra of the 4f—5d transitions of the Ce³⁺ ion in the region of 4–8 eV were studied in Ce³⁺-doped Na_0.4Lu_0.6F_2.2 single crystals. Luminescence spectra in the ultraviolet and visible spectral regions, luminescence decay kinetics and reflection and luminescence excitation spectra in the visible/ultraviolet and ultraviolet regions (4–20 eV) were investigated at helium and room temperatures.     

Ultraviolet sum-frequency generation utilizing optical pair interactions in solids

We report the first observation of nonlinear generation of broadband ultraviolet light by pair interactions in a solid. Emission from PrF₃ on numerous features between 270–410 nm is ascribed to transitions of coupled atoms. They occur at sum-frequencies of known Pr³⁺ intraconfigurational transitions and show quadratic dependence on input power. High intensities and structured excitation spectra are observed. The prospect of stimulated ultraviolet pair emission with visible light excitation is examined.     

Absorption of Dy3+ and Nd3+ ions in BaR 2F8 single crystals

The Dy³⁺ absorption and excitation spectra of BaY₂F₈ and BaYb₂F₈ single crystals are investigated in the ultraviolet, vacuum ultraviolet, and visible ranges at a temperature of 300 K. These crystals exhibit intense broad absorption bands due to the spin-allowed 4f-5d transitions in the range (56–78) × 10^?3 cm^?1 and less intense absorption bands that correspond to the spin-forbidden transitions in the range (50–56) × 10^?3 cm^?1. The Nd³⁺ absorption spectra of BaY₂F₈ single crystals are studied in the range (34–82) × 10^?3 cm^?1 at 300 K for different crystal orientations.     

利用三阶微商吸收光谱确定C60分子能隙

利用三阶微商吸收光谱观测到可见区C₆₀分子电子光谱中丰富的振动光谱结构.通过对此类电子-振动跃迁的指认分析，给出了C₆₀分子部分振动模频率，确定了C₆₀分子能隙. 关键词：     

Vacuum ultraviolet spectroscopy of pure and Ce3+-doped Na0.4Lu0.6F2.2

The spectroscopic properties of wide-band fluoride Na_0.4Lu_0.6F_2.2 crystals activated by Ce³⁺ were investigated. The absorption edge for the matrix was found to be at about 9.5 eV. In the 4- to 8-eV region of the absorption spectrum of Na_0.4Lu_0.6F_2.2: Ce³⁺, all 4f-5d transitions of the Ce³⁺ ion are observed. In Na_0.4Lu_0.6F_2.2: Ce³⁺ crystals, ultraviolet/visible emission, reflection and time-resolved vacuum ultraviolet/ultraviolet excitation spectra were recorded at liquid helium and room temperatures.     

Optical absorption spectra of some transition metal thiophosphates

Near-infrared and visible absorption spectra at room temperature of MnPS₃, CoPS₃, CoPS₃ are reported. These materials show weak structures below their fundamental absorption thresholds, due to the 3d-3d transitions occurring on the transition metal ion. By comparison with other transition metal compounds, such excitations are interpreted on the basis of the ligand field theory. The appearance of well developed crystal field spectra is a further confirmation that these materials are considerably ionic.     

Electronic and RAMAN Spectra of an Iron-Dioximato Polymer

Electronic and resonance Raman spectra are reported for the [Fe(Hdmg)₂(clpz)]_n polymer (clpz = 2-chloropyrazine, Hdmg = dimethylglyoximato anion). Excitation at the absorption bands in the visible region led to a selective enhancement of vibrational modes of the Hdmg and clpz ligands, allowing the characterization of the metal-to-macrocycle and metal-to-axial ligand charge-transfer transitions.     

Absorption,excitation and fluorescence spectra of thallium activated cesium bromide

Absorption, excitation and fluorescence spectra of T1⁺ doped cesium bromide have been investigated at various thallium concentrations. At very low thallium concentration two absorption bands are obtained at 225 nm and 264 nm. With rise of thallium concentration additional absorption bands are obtained at 230, 244, 258, 270 and 285 nm. A single bell-shaped fluorescence band at 357 nm in the ultraviolet region is obtained at low thallium concentration. Two additional visible fluorescence bands appear at 440 and 540 nm with rise in thallium content. The excitation spectra for ultraviolet emission band and visible emission bands are found to be different. Accordingly the ultraviolet emission band is attributed to the characteristic A emission in T1⁺ ion and the visible bands are attributed to dimer centers havingD _4h site symmetry.     

Diffuse Reflectance Spectra of Rare Earth Benzoylacetonates in Ultraviolet region

Rare earth β-diketonates are promising laser materials. Their solid state spectra is expected to give their spectral characteristics. The diffuse reflectance spectra of some rare earth β-diketonates and esters in ultraviolet region have been reported recently by the authors¹. The ultraviolet absorption spectra of transition metal chelates have also been reported^2,3 recently. The spectra of the non-transition metal ion chelates usually consist⁴ only of the metal charge transfer and ligand intramolecular transitions. The ligand transitions in all the cases are characteristic of the coordinated ligand. The spectrum of the ligand, however, helps in assigning the transitions of the co-ordinated ligand. A comparison of the spectrum of ligands and their rare earth complexes^1,5,6 shows that on complexation no new bands appear in ultraviolet suggesting that unlike transition metal β-diketonates^2,3, charge transfer bands do not appear in the present case. The ligand intramolecular transitions are expected mainly due to the carbonyl group.     

Time-Resolved Vacuum Ultraviolet Spectroscopy of Er<Superscript>3+</Superscript> Ions in the SrF<Subscript>2</Subscript> Crystal

The photoluminescence and photoexcitation spectra as well as the luminescence decay kinetics of Er³⁺ ions in the visible ultraviolet and vacuum ultraviolet (VUV) regions have been studied by the method of low-temperature, time-resolved VUV-spectroscopy on excitation by synchrotron radiation. In the VUV spectral region of the luminescence of SrF₂:1% Er³⁺, the 146.5-nm band with a time of decay of less than 0.6 nsec was revealed together with the well-known emission band at 164.3 nm (decay constant in the microsecond range). Its possible nature is discussed. The specific features of the formation of photoexcitation spectra of the f-f and f-d transitions in the Er³⁺ ion are considered. Competition between the processes of excitation of f-f and d-f luminescence has been revealed. It manifests itself in the inverse relationship of their photoexcitation spectra in a range of energies of incident photons that are close to the position of the 4fⁿ⁻¹5d configuration levels. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 519–523, July–August, 2005.     

溶胶-凝胶制备ZnO-SiO2复合膜的量子效应和上转换发光

采用溶胶-凝胶技术在玻璃衬底上制备了ZnO薄膜和ZnO-SiO₂复合膜.原子力显微镜照片显示ZnO薄膜具有球状纳米晶粒;可见光-紫外透射光谱表明ZnO-SiO₂复合膜在可见光区的透过率大约是85%,透过率从330 nm开始下降,到290 nm附近降为零.由于量子效应,吸收边出现明显的蓝移.在室温下用不同波长的光激发ZnO-SiO₂复合膜,光致发光谱显示ZnO-SiO₂复合膜对应于激子发射的290 nm附近的紫外发光峰与透射谱所显示的吸收边位置一致,没有出现斯托克斯红移.同时,ZnO-SiO₂复合膜出现了双光子和三光子吸收现象和上转换发光现象. 关键词： 2')" href="#">ZnO-SiO₂ 量子效应 双光子和三光子吸收 上转换发光     

Effect of substituent on UV–visible absorption and photostability of liquid crystals: DFT study

The electronic transitions in the ultraviolet–visible (UV–Vis) range of two nematogens, namely 4′-cyanophenyl-4-n-pentylbenzoate and 4′-cyanophenyl-4-n-pentoxybenzoate, have been studied. The UV–Vis and circular dichroism spectra of these molecules have been simulated using the TDDFT/B3LYP/6-31+G(d) method. Mulliken atomic charges for each molecule have been compared with Loewdin atomic charges to analyze the molecular charge distribution and phase stability. The highest occupied molecular orbital and lowest unoccupied molecular orbital energies corresponding to the electronic transitions in the UV–Vis range have been reported. The excited states have been calculated via configuration interaction singles with semi-empirical Hamiltonian ZINDO (Zerner's intermediate neglect of differential overlap method). Further, the effect of substituent on ultraviolet absorption and photostability of the molecules has been discussed. The photostability of the molecules has been investigated in order to understand the application and operation with ultraviolet and visible light regions.     

Magnetic circular dichroism of Pr3+ ions in yttrium—Aluminium garnet crystals

The spectra of the absorption and magnetic circular dichroism in the praseodymium-yttrium garnet-aluminate Pr³⁺:YAG have been studied within the visible and near ultraviolet (UV) spectral range for temperature T = 90 K and 300 K. Analysis of the spectral and the temperature dependences of the magnetooptical and optical spectra has made it possible to identify the optical 4f → 4f transitions occurring between the Stark sublevels of the ¹ D ₂, ³ P ₀, and ³ H ₄ multiplets in Pr³⁺:YAG. It has been shown that in the MCD mechanism in Pr³⁺:YAG within the visible and UV spectral range for the absorption bands due to both forbidden 4f → 4f and allowed 4f → 5d transitions, a significant role is being played by the effect of quantum-mechanical “mixing” of the states of the three lowest-energy Stark singlets of the ground-state ³ H ₄ multiplet of the non-Kramers RE Pr³⁺ ion.     

Crystal growth, spectroscopy, and diode pumped laser performance of Pr,?Mg:SrAl12O19

Polarization dependent ground state absorption, excited state absorption and emission cross sections of Pr,?Mg:SrAl₁₂O₁₉ are determined in the visible and ultraviolet spectral region. It is shown that excited state absorption to the 4f5d configuration does neither occur on the pump wavelength in the blue region nor on any of the visible laser transitions. Efficient laser action at 643.5?nm is demonstrated with slope efficiencies of up to 47% with respect to the absorbed pump power. Output powers up to 75?mW are achieved by pumping with an InGaN laser diode at 444?nm.     

Nd3+ near UV and visible fluorescence in YAP:Nd

The present paper summarizes detailed investigations of Nd³⁺ fluorescence spectra in YAP:Nd laser crystal in the broad spectral range of 370–1100 nm at liquid nitrogen temperature. Especially, Nd³⁺ near UV and visible fluorescence spectra were studied for the first time in this crystal. The Nd³⁺ near UV and visible fluorescence spectra of this crystal consist of many narrow lines (up to 50). The Nd³⁺ near UV and visible fluorescence lines arise mainly from⁴D_3/2 and²P_3/2 Nd³⁺ terms (transitions from⁴D_3/2,²P_3/2 to lower lying Nd³⁺ levels are responsible for their appearance). At room temperature the fluorescence spectra consist of broad bands with narrow lines (mainly⁴D_3/2⁴F_3/2,⁴F_5/2 and²H_9/2 transitions).     

Dissociative excitation of the fluoromethanes by electron impact

Emission spectra following electron impact on molecules of the homologous series of fluoromethanes CH_xF_4-x with x=0-4 have been investigated from the near infrared at 700 nm to the ultraviolet VUV-spectral region at 100 nm. Earlier experimental data for the visible and ultraviolet spectral region were revised and evaluated again on the basis of reliable new data for the dynamic viscosity of the molecules. The measurement of absolute and relative cross-sections were systematically extended into the VUV region from 100 nm to 200 nm. The examination of atomic lines as well as molecular band systems in the VUV gives further insight into the dissociation mechanism and shows that many excited levels even of atomic and molecular species cannot be populated directly, but only by transitions from higher-lying energy levels. Simple steric effects can be distinguished from more complex transition phenomena. Received: 25 February 1998 / Revised: 29 May 1998 and 18 June 1998 / Accepted: 23 June 1998     

5d-4f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF₂, SrF₂, BaF₂) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5d state to different 4f levels of rare earth ions.     

中子探测晶体Li6Gd(BO3)3:Ce的光谱特性研究

文章用提拉法生长出Li₆Gd(BO₃)₃:Ce晶体,并对其光谱性能与发光过程进行了探索. 借助于真空紫外-紫外透过光谱测试,发现晶体的透过光谱中存在Ce³⁺离子和Gd³⁺的特征吸收峰,同时还存在与Ce⁴⁺离子相关的电荷迁移带. 对晶体的真空紫外-紫外激发发射光谱进行研究发现,在晶体存在着Ce³⁺离子的5d→4f辐射跃迁发光与Gd³⁺离子的4f→4f辐射跃迁发光,而且存在着Gd³⁺→Ce³⁺之间的能量传递. 对Li₆Gd(BO₃)₃:Ce晶体的X射线与γ射线激发发射光谱研究可知,晶体在高能射线激发下的闪烁光主要是Ce³⁺离子的发光. 关键词： 6Gd(BO₃)₃:Ce晶体')" href="#">Li₆Gd(BO₃)₃:Ce晶体 真空紫外-紫外透过光谱 真空紫外-紫外激发发射光谱 能量传递     

Synthesis and characterization of TiO2/MoO3/carbon clusters composite material

Nano-sized TiO₂/MoO₃/carbon clusters composite material has been successfully obtained by the calcinations of a TiO(acac)₂/MoO₂(acac)₂/epoxy resin complex under an oxygen atmosphere. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis and surface characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The ultraviolet–visible (UV–Vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. ESR spectra of the composite materials suggest that they have visible light-responsive catalytic ability with an electron transfer process of carbon clusters → MoO₃ → carbon clusters → TiO₂.     

Luminescence and electronic excitations in crystals K<Subscript>2</Subscript>Al<Subscript>2</Subscript>B<Subscript>2</Subscript>O<Subscript>7</Subscript> with defects

This paper reports on the results of the comprehensive study of the dynamics of electronic excitations in K₂Al₂B₂O₇ (KABO) crystals, obtained by low-temperature luminescence vacuum ultraviolet spectroscopy with nanosecond time resolution upon photoexcitation by synchrotron radiation. For the first time, the data have been obtained on the photoluminescence (PL) decay kinetics, PL spectra with time resolution, PL excitation spectra with time resolution, and reflection spectra at 7 K; the intrinsic nature of PL at 3.28 eV has been established; luminescence bands of defects have been separated in the visible and ultraviolet spectral regions; an intense long-wavelength PL band has been detected at 1.72 eV; channels of the formation and decay of electronic excitations in K₂Al₂B₂O₇ crystals have been discussed.