Estimate of the wavelengths for the first and second resonance lines in the francium I spectra

Relativistic self-consistent-field wavefunctions have been used to calculate one-electron eigenvalues for the ground s-state, the first and the second excited p-states of Sr II, Cs I, Ba II, Fr I and Ra II. When knowing the difference between the experimental energies and the theoretical ones for Sr II, Cs I, Ba II and Ra II the wavelengths for the first and second resonance lines in Fr I have been estimated with the following result: λ(7²P_1/2? 7²S_1/2)=812±10) nm λ(7²P_3/2? 7²S_1/2)=719±10) nm λ(8²P_1/2? 7²S_1/2)=433±5) nm λ(8²P_3/2? 7²S_1/2)=423±5) nm     

Dye-laser amplified,atomic absorption flame spectroscopy

In this letter we report the detection of atomic absorption lines of Na, Li, Sr, Ba and Cs, by using a flashlamp-pumped dye laser with an acetylene-air flame inside the cavity. A new technique for a quantitative photo-electrical measurement is proposed. In case of Na (5890 Å), a sensitivity of 0.016 ppb/1% extinction and a minimum detectable concentration of 0.2 ppb are obtained. The sensitivity and the detectable limit are improved by a factor of 10³ and 10, respectively, compared with a conventional analysis by an atomic absorption flame spectrophotometer.     

Level-Crossing-Untersuching der Stark-Aufspaltung der tiefsten1 P 1-Terme von Ca,Sr und Ba

Using the level-crossing technique, magnitude and sign of the tensor polarizability α_ten of the lowest¹ P ₁-levels of Ca, Sr, and Ba have been measured by investigating the splitting into Zeeman-sublevels in superimposed homogeneous electric and magnetic fields. The experimental results are: α_ten/g _J =?13.6(3) kHz/(kV/cm)² for Ca α_ten/g _J =?14.32(15) kHz/(kV/cm)² for Sr α_ten/g _J =?10.72(10) kHz/(kV/cm)² for Ba, where theg _J -values are approximatelyg _J≈1. With greater accuracy the ratios of these constants have been determined by eliminating the electric-field strength measurement: (α_ten(Sr)/g _J (Sr))/(α_ten(Ca)/g _J (Ca))=1.050(8) (α_ten(Sr)/g _J (Sr))/(α_ten(Ba)/g _J (Ba))=1.336(2). The polarizability constants are discussed with regard to the state vectors of the lowestsp ¹ P ₁- and³ P ₁-levels. The tensor polarizability of the 6s 6p¹ P ₁-level of Ba I is considered in relation to oscillator strengths of electric dipole transitions to neighbouring levels.     

Wing profile measurements of the resonance emission lines of Na (5890/96Å) and Sr (4607Å) in flames

The blue and red wing intensity distributions of the Na 5890Åand 5896Åresonance lines were measured in emission in a pre-mixed, laminar, shielded H₂/O₂ flame at 1 atm with Ar or N₂ as diluent gases (T≈2000 K). The wavelength range scanned amounted to about 20Åfrom line center. In addition, we measured the wing intensity distributions of the resonance line of Sr (4607Å) in CO/N₂O flames at 1 atm (T≈2800 K) in a wavelength range of about 10Åfrom line center. The scanning monochromator used in these emission experiments had a spectral bandwidth of 0.30±0.04Å.For the resonance lines of Na and of Sr, the wavelength dependence of each wing was derived from 25 repeated scans and found to differ from theoretical predictions based on binary quasistatic theory.The red wing of the D₁ line of Na was investigated for the occurrence of satellites. We discovered a structure resembling a “smoothed” satellite at about 12Åfrom line centre. A satellite-like structure was also found in the blue wing of the resonance emission line of Sr at about 5Åfrom line center.     

Tunable diode laser spectroscopy of CO2 in the 10- to 15-μm spectral region—Lineshape and Q-branch head absorption profile

The self-broadened and nitrogen-broadened absorption profiles of the Q-branch head of the 10⁰0 ← 01¹0 band of CO₂ near 618 cm^?1 were studied under high resolution (～10^?4 cm^?1) using tunable diode laser techniques. The intensity and linewidth of several lines in this Q branch, the ν₂ band, 10.4-μm and 9.4-μm laser bands have been measured accurately. The lineshape of a CO₂ line has also been measured to be Lorentzian within experimental accuracy to about 15 half-widths. Preliminary calculated Q-branch head absorption profiles agree reasonably well with the observed profiles.     

Study of the Structures of the Tetragonal Paramagnetic Centers in the Mixed Fluorite Crystals with Rare-Earth Ions by EPR

Electron paramagnetic resonance (EPR) of the mixed fluorite crystals with the general formula (MeF₂)_1?x?y (REF₃) _x (RF₃) _y (Me = Ca, Sr, Ba; R = Y, La, Lu; RE—paramagnetic trivalent rare-earth ions) were studied comprehensively by different authors and several structural models of paramagnetic centers were considered. However, a lot of details of EPR spectra still remain unexplained. In this work some modifications of the simplest models are proposed which allow explaining adequately the variety of the tetragonal centers in crystals grown under the different conditions. The calculated from the proposed models components of g-factors for Ce³⁺, Nd³⁺, Sm^3+, Er³⁺ ions are in a good agreement with the experimental values.     

红色LiMBO3 : Re3+(Re=Eu,Sm) 发光材料的特性

采用固相法制备了红色LiM(M=Ca, Sr, Ba)BO₃ : Re³⁺(Re=Eu, Sm)发光材料,研究了材料的发光性能。研究发现LiM(M=Ca, Sr, Ba)BO₃ : Eu³⁺材料呈现多峰发射,最强发射分别位于610,615,613 nm处,分别监测这三个最强峰,所得激发光谱峰值位于369,400,470 nm。LiM(M=Ca, Sr, Ba)BO₃ : Sm³⁺材料也呈多峰发射,分别对应Sm³⁺的⁴G_5/2→⁶H_5/2、⁴G_5/2→⁶H_7/2和⁴G_5/2→⁶H_9/2跃迁发射;分别监测602,599,597 nm三个最强发射峰,所得激发光谱峰值位于374,405 nm。研究了激活剂浓度对材料发射强度的影响,结果随激活剂浓度的增大,发射强度先增强后减弱,即,存在浓度猝灭效应。实验表明,加入电荷补偿剂Li⁺、Na⁺或K⁺均可提高LiM(M=Ca, Sr, Ba)BO₃ : Re³⁺(Re=Eu, Sm)材料的发射强度。     

Dependence of the spectral width of the self-absorbed Sr 4607.33Åresonance line on Sr atomic density in a flame

Using a pressure-scanned Fabry-Pérot interferometer, we measured spectral profiles of the self-absorbed Sr resonance line at 4607.33Åemitted in a pre-mixed, laminar, shielded air-C₂H₂ flame at 1 atm for various Sr-solution concentrations. The dependence of the full width at one-half maximum (FWHM) on Sr atomic density in the flame was found to agree with a calculation based on the Voigt expression and Beer's law. It appears that one can derive the FWHM under optically thin conditions (i.e. at vanishing Sr atomic density) by linear extrapolation from measurements made at higher concentrations where the signal-to-noise ratio is good, but broadening due to self-absorption plays a role.     

g J -Faktoren der tiefsten3 P 1-Zustände von Strontium und Barium

Theg _J -values of the lowest³ P ₁-states of Sr and Ba have been determined with optical double resonance. The measurement has been carried out by observation of radiofrequency transitionsΔm _j =± 1 between Zeeman levels of the even isotopes. Calibration of the magnetic field has been done by optical pumping of the 3²S_1/2 ground state of the sodium atom. The results are:g _j ^exp (5s 5p ³ P ₁, Sr)=1.50065(4)g _j ^exp (6s 6p ³ P ₁, Ba)=1.49651(7).     

Messung der magnetischen Kerndipolmomente an freien43Ca-,87Sr-,135Ba-,137Ba-,171Yb- und173Yb-Atomen mit optischem Pumpen

As previously reported^3,4 the optical pumping method was succesfully used to determine the nuclear magnetic moments of¹³⁵Ba,¹³⁷Ba,¹⁷¹Yb and¹⁷³Yb. This method has now been extended to⁴³Ca and⁸⁷Sr. The nuclear moments of the Ba- and Yb-isotopes have been remeasured by means of an improved experimental technique. Especially the influence of the light shift has been investigated and the nuclear moments have been corrected by eliminating this shift. The magnetic field has been calibrated by means of optical pumping of²³Na. The nuclear magnetic moments obtained from the rf-transitions between the Zeeman-levels of the ground state¹ S _o are: μ(⁴³Ca)=?1.3172 (6)μ _N ; μ⁸⁷Sr)=?1.0924 (7) μ _N ; μ(¹³⁵Ba)=0.83656(2)μ _N ; μ(¹³⁷Ba)=0.93582(2)μ _N ; μ(¹⁷¹Yb)=0.491889 (8)μ _N ; μ(¹⁷³Yb)=?0.67744 (3) μ _N (diamagnetic correction was applied). The ratios of the nuclear moments of the elements with two odd isotopes are: μ(¹³⁷Ba)/(¹³⁵Ba)=1.11865 (3); μ(¹⁷³Yb)/μ(¹⁷¹Yb)=?1.37723 (7). In comparison with the results of nuclear induction the chemical shifts have been calculated to be: δ(Ca)≦± 5 · 10^?4 δ(Sr)=?6(7) ·10^?4 δ(Ba)=?7.8(4) ·10^?4 δ(Yb)=?23(10) · 10^?4.     

Levelcrossing experiments in the first excited1 P 1 states of the alkaline earths

The hyperfine structure of the lowest¹P₁ state of²⁵Mg,⁴³Ca,⁸⁷Sr,¹³⁵Ba and¹³⁷Ba have been measured by the level-crossing and anticrossing technique. The magnetic dipole and electric quadrupole coupling constants determined by these measurements are²⁵Mg(3s3p¹P₁):A=? 7.7(5) MHz; 16 MHz>B>0 MHz,⁴³Ca(4s4p¹P₁):A=? 15.3(4) MHz; ¦B¦<12 MHz,⁸⁷Sr (5s5p¹P₁:A=? 3.4(4) MHz;B=39(4) MHz,¹³⁵Ba(6s6p¹P₁):A=? 97.5(1.0) MHz;B=31(9)MHz,¹³⁷Ba(6s6p¹P₁):A=?109.2(1.2) MHz;B=51(12)MHz. The results have been compared with the predictions of the Breit-Wills theory of the two-electron hyperfine structure using the experimental data on the³P states. Large discrepancies have been observed which are due to different radial wave functions of thes andp electron in the triplet and singlet system. This effect has been taken into account by fitting the data with the aid of two additional parameters. That this procedure is justified is shown by an analysis of the fine structure splitting, the life times, and the isotopic shifts in thesp configurations of group II elements.     

Peculiarities of cascade photon emission and energy storage in M1−xPrxF2+x (M=Ca,Sr, Ba,x≈0.35) crystals

Peculiarities of cascade photon emission (CPE) and energy storage in M_1?xPr_xF_2+x (M=Ca, Sr, Ba, x≈0.35) crystals were studied. The investigation of lattice parameters revealed that these solid solutions belong to the fluorite structure type with the lattice constant noticeably different from that of MF₂ crystals. Absorption, emission and excitation spectra of M_0.65Pr_0.35F_2.35 were measured at LHeT and RT. As it turned out the typical for 4f²→4f² transition in Pr³⁺ emission lines are broadened as compared with the PrF₃ crystal. The analysis of the excitation spectra broadening does not allow bringing out the type of the superlattice, which is inherent to the material, but it indicates clearly the simultaneous presence of different types of the Pr centers in mixed crystals. Yet another specific feature is the higher radiation sensitivity of these fluorides relatively PrF₃, MF₂ and Pr-doped MF₂ crystals. Coloration efficiency enhances in direction Ca→Sr→Ba, and the positions of induced absorption band depend on composition of the solid solution. Colorization, thermo-stimulated luminescence and afterglow of the M_1?xPr_xF_2+x crystals denote high radiation sensitivity as compared with M_1?xCe_xF_2+x.     

Raman spectroscopy of BaTiO3/(Ba,Sr)TiO3 superlattices

A series of BaTiO₃/Ba_{1 ? x} Sr _x TiO₃ (BT/BST) superlattices were prepared by pulsed laser deposition on MgO substrates with a constant period of 80 Å (40 Å BT and 40 Å BST) and varying compositions of the BST layer so that the Ba/Sr concentration ratios were 0/100, 30/70, 40/60, 50/50, 60/40, 70/30, 100/0. The soft mode E(1TO) of the polarized Raman spectra transformed depending on the Ba/Sr ratio in the BST layer. As the Sr concentration in the BST layers increased from 0 to 100%, the E(1TO) soft mode half-width varied from 171 to 103 cm^?1 and its frequency increased from 31 to 109 cm^?1 due to the interaction between the epitaxial layers forming the superlattices.     

Tunable diode laser measurements of the band strength and collision halfwidths of nitric oxide

The strength of the fundamental absorption band of nitric oxide at 5.3 μm and collision halfwidths of nitric oxide lines broadened by nitrogen, argon, and combustion gases were measured in absorption cell, flat flame and shock tube experiments using a tunable diode laser. Room temperature absorption measurements were made in an absorption cell filled with NO/N₂ or NO/Ar mixtures or with probe-extracted combustion gases. High temperature (to 2500 K) absorption measurements were performed for NO in N₂ and NO in Ar using a shock tube, and for NO in combustion gases using a flat flame burner.Absorption measurements were made on lines from 1860–1925 cm^?1, ($\text{Ω=}\text{1}\text{2}$ and $\text{3}\text{2}$,P($\text{5}\text{2}$-R ($\text{29}\text{2}$)) resulting in a band strength of 123±8 cm^-2 atm^?1 at 273.2 K. Collision halfwidth dependencies for each broadening species were examined as a function of rotational quantum number and temperature.     

Low rotational transitions of the CF3H molecule: The pressure-induced shift and broadening

Using a microwave spectrometer with a radioacoustic signal detection, the absorption profiles in the multiplets of the low rotational transitions J’?J = 2?1, 3?2, 4?3, and 5?4 of the ¹²CF₃H molecule in the ground vibrational state at pressures of pure gaseous CF₃H from 0.1 to 1.3 Torr when all the K components of the multiplets merge into a single spectral line are studied. The parameters of the pressure-induced shift and broadening of the observed lines are determined by comparing the theoretically modeled absorption signal and the experimental spectrum. The model used takes into account weak lines corresponding to the excited vibrational states v₃ and v₆ of the ¹³CHF₃ molecule and the instrumental features of the spectrometer. The observed multiplet is simulated as an isolated Lorentzian line and as a sum of the profiles of the K components with known unshifted positions and known amplitude ratio. The shift and broadening parameters obtained in both cases are shown to agree well with each other. The dependences of the shift and broadening parameters on the quantum number J are analyzed and compared with the previously obtained data for the lines J’?J = 1?0 and 2?1.     

Bestimmung von Oszillatorenstärken durch Lebensdauermessungen der ersten angeregten Niveaus für die Elemente Ba,Sr, Ca,In und Na

The lifetimes of the first excited state of the elements Ca, Sr, Ba, In and Na were measured with the method ofOsberghaus ¹. Oscillator strengthes (f) of resonance lines were computed from the measured lifetimes (τ). The measurements were corrected for imprisonment of radiation in the investigated vapor. The error of the τ-values was estimated to be approximately three percent. We got following resultslifetimes for Ca 4¹ P ₁ (4·67±0·11)·10^?9sec, for Sr 5¹ p ₁ (4·56±0·21)·10^?9 sec, for Ba 6¹ p ₁ (8·36±0·25)·10^?9sec, for In 6² S _1/2 (8·531±0·085)·10^?9sec and for Na 3² P-dublett (1·59±0·039)·10^?8sec. For the Na 3² P-dublett the dependency of the lifetime on the pressure of foreign gases (N₂, C₃H₈, C₆H₅?CH₃) was studied.     

Ba原子6s6p1P1←6s6s1S0跃迁的光腔衰荡光谱

建立了一套光腔衰荡原子束吸收光谱测量装置,并对Ba原子的6s6p¹P₁←6s6s¹S₀吸收谱线用光腔衰荡光谱方法进行了测量,得到了Ba原子在553.548nm不同温度下的吸收谱线线型.实验结果表明,该装置测量吸收灵敏度达到6×10^-7. 关键词： 光腔衰荡 吸收光谱 Ba原子     

Fe-based perovskite-type oxides as excellent oxygen-permeable and reduction-tolerant materials

Development of new mixed conductors with both high oxygen permeability and phase stability under reducing atmosphere is indispensable for realizing practical MIEC systems of oxygen separation and membrane reactor. In this study, a family of Co-free Fe-based perovskite-type oxides, (Ba,Sr)(Fe,Mn)O_3−δ was prepared and their oxygen permeability and phase stability against reduction were examined. Optimum Ba doping concentration at A site was found around 30%, and Ba_0.3Sr_0.7FeO_3−δ showed highest oxygen permeability (3.0 cm³(STP)cm^− 2 min^− 1 at 900 °C) in this study. Perovskite-type oxides of the Ba–Mn–Fe–O and Ba–Sr–Mn–Fe–O systems with appropriate compositions preserved the structure even after annealing in the reducing atmosphere of 5% H₂/N₂ at 1000 °C, showing their exceeding reduction tolerance.