George V. Shalimoff

Crystal field analysis of Tm3+ and Yb3+ in YPO4 and LuPO4

The optical and near infrared absorption of dilute Tm3+ and Yb3+ impurities in YPO4 and LuPO4 single crystals have been measured at liquid helium and nitrogen temperatures. For Tm3+, the spectral region from 5 000 to 38 000 cm−1 was examined and Zeeman spectra were obtained in the visible region. The observed transitions were assigned and fit to a semiempirical Hamiltonian with adjustable parameters via a least‐squares procedure. Satisfactory fits and good agreement between the calculated and measured g values were obtained. For Yb3+, there are more parameters than experimental levels, so ζ, B20, B40, and B44 were adjusted, while B60 and B64 were fixed at the values found for Tm3+. Energy levels and Zeeman splittings calculated with these parameters are in good agreement with the measured quantities.

Optical spectra and Zeeman effect for Pr3+ and Nd3+ in LuPO4 and YPO4

Absorption spectra of Pr3+ and Nd3+ diluted in LuPO4 and YPO4 crystals have been measured from 4000 to 30 000 cm−1, at liquid He and N2 temperatures. Fluorescence was observed for Pr3+ and Nd3+ in YPO4, and Zeeman spectra were obtained in the visible region. The transitions were assigned and fit to a semiempirical Hamiltonian with adjustable parameters via a least squares procedure. Satisfactory fits and reasonable agreement between calculated and measured g values were obtained.

OPTICAL SPECTRA AND ZEEMAN EFFECT FOR Er3+ IN LuPO4 AND HfSiO4

The absorption spectra of Er3+ diluted in LuPO4 and HfSiO4 crystals have been measured from 6000 to 28 000 cm−1 at liquid He and N2 temperatures. Zeeman spectra were obtained in the visible region. The transitions were assigned and fitted to a semiempirical Hamiltonian with ten adjustable parameters. Satisfactory fits were obtained including reasonable agreement between calculated and measured g values.

Zur Elektronenstruktur metallorganischer verbindungen der f-Elemente: XXXIV. Ist der N,N′-bis(trimethylsilyl)benzamidinato-Ligand im Falle von Lanthanoid-Zentralionen ein elektronisches Äquivalent zum η5-Cyclopentadienyl-Liganden?☆

Abstract Magnetic data and the results of low temperature absorption, luminescence and magnetic circular dichroism spectra of 4-methoxy-substituted lanthanide ( III )tris[ N , N ′-bis(trimethylsily)benzamidinates [(MeOBA) 3 Ln; Ln  Eu ( 1 ), Pr ( 2 )], and of adducts derived from tris(η 5 -cyclopentadienyl)-europium( III ) [CP 3 EuX; X  CNC 6 H 11 ( 3 ), THF ( 4 )] are reported. In case of 1 , 3 and 4 the 151 Eu Mossbauer spectra also were recorded. On the basis of the optical measurements the truncated crystal field (CF) splitting patterns of 1 and 2 were derived. The parameters of an empirical Hamiltonian were fitted to the experimentally derived splitting patterns. The parameters obtained suggest that the BA ligand may be considered to a certain extent as an electronic equivalent to the Cp ligand in case of Ln central ions with small electron affinity. In case of central ions with higher oxidation power such as Eu 3+ , the BA ligand behaves in a conventional manner. The Cp ligand, however, causes unusual physical properties which cannot be explained on the basis of an Eu 3+ , central ion which is surrounded by three Cp ligands.

On the stability and bonding in bis(η-arene)ianthanide complexes

Cocondensation of atoms of the lanthanide elements with 1,3,5-tri-t-butylbenzene gives the thermally stable bis(η-arene)lanthanide(0) sandwich compounds for the lanthanides Nd, Tb, Dy, Ho, Er, and Lu, thermally unstable complexes for La, Pr and Sm, and unisolable materials for Ce, Eu, Tm, and Yb; a simple bonding model is proposed to account for the stability trends, and for the magnetism of the stable complexes.

The electronic structure of organometallic complexes of the f elements XXVIII: Interpretation of the optical and magnetochemical data of a cyclohexylisocyanide adduct derived from Tris(η5-cyclopentadienyl)samarium(III)

Abstract The absorption spectrum of Cp3Sm·CNC6H11 has been measured at room temperature and at low temperatures in a hydrocarbon glass and in a KBr pellet. Electron paramagnetic resonance and magnetic susceptibility measurements are also reported in this paper. The observed optical bands were assigned on the basis of calculations which assumed that the crystal field parameters of the samarium complex were the same as for the previously analyzed Cp3Pr·CNC6H13. The parameters of an empirical Hamiltonian were fitted to the energies of 39 levels to give an r.m.s. deviation of 21 cm−. On the basis of the wavefunctions of the crystal field ground state obtained from the fit, the ground state g values and the temperature-dependent magnetic susceptibility were calculated and compared with the experimental values.

Zur elektronenstruktur hochsymmetrischer Verbindungen der ⨍-elemente–XXIII. Wie groß sind die Kristallfeldaufspaltungseffekte bei den Tris (bis (trimethylsilyl) amido)-Komplexen der Lanthanoiden?

Abstract The σ and π absorption spectrum of the 3 H 4 → 3 P 0 transition has been measured at room temperature on an oriented single crystal of tris(bis(trimethylsilyl)amido)praseodymium (III) as well as the room temperature magnetic circular dichroism spectrum of the compound dissolved in a mixture of toluene and methylcyclohexane in the ratio 1:1. From these data the crystal field (CF) splitting of the ground 3 H 4 manifold was derived. An approximate set of CF parameters was obtained which qualitatively reproduces the experimental levels. The magnitude of the CF parameters demonstrates that the three bis(trimethylsilyl)amido ligands produce an unusually large crystal field.

Spectrochemical Determination of Strontium-to-Calcium Ratio in Food, Milk, Cream, Blood Feces, and Urine of Cows

A d.c carbon-arc spectrochemical method has been developed for the determination of strontium-to-calcium ratios in the food, milk, cream, blood, feces, and urine of cows. In this method sodium is added to the samples to produce uniformly enhanced and reproducible spectral lines in the range of 10−4 to 5 × 10−2 strontium-to-calcium ratio. Typical examples of analyses of the food and products of three cows are included, with a precision of ±12%

The 3d 2 –3d4f transitions in V iv†

The 3d4f levels in the spectrum of triply ionized vanadium, V IV, were located by L. Iglesias. She located these levels by identifying transitions from the 3d{sup 2} ground configuration to the 3d4p levels, then to the 3d4d levels and finally to the 3d4f levels. She also identified the transitions from the 3d4d levels to the 3d5p levels, continued up to the 3d5d levels, then back down to the 3d4f levels. Though the 3d4f levels were well established by two routes, the direct transitions from the ground state were not observed, being beyond her experimental range which stopped at 675 {angstrom}. We have photographed the spectrum of vanadium in the region of 190-650 {angstrom} and the direct transitions from 3d{sup 2} to 3d4f have been observed. The spectrum was excited with a vacuum sliding-spark discharge between vanadium metal electrodes separated by a quartz spacer as described previously. Peak discharge current was 1000 {angstrom}. The spectrum was photographed on Kodak SWR plates using the 10 {center_dot} 7 m grazing incidence spectrograph at the National Bureau of Standards in Washington, D.C. The plate factor in the region of interest is about 0.27 {angstrom}/mm. The plates were measured on a Grant comparator. Lines of yttrium IV and V, oxygen III and carbon IV were used for reference standards. The same plates were used to obtain the spectrum of vanadium V as reported previously by van Deurzen. Table I contains 19 transitions from the ground configuration, 3d{sup 2}, to the 3d4f configuration and 3 transitions from the ground configuration to the 3dSp configuration. Column 1 in the table is our measured vacuum wavelengths. The intensities in column 2 are visual estimates on a scale of 0 to 9. Column 3 lists the wavenumber of the measured lines. The classifications of the transitions and the odd-even level values are given in columns 4 and 5 and are taken from Iglesias. The difference, {Delta}, between the wavenumber of the observed line and the wavenumber calculated from Iglesias levels are given in column 6. The mean difference of column 6 is 0.6 cm{sup -1}. Since a measured change of 0.001 {angstrom} at 378 {angstrom} corresponds to 0.7 cm{sup -1}, we can say that the wavelengths obtained by the two methods agree to within {+-} 0.001 {angstrom}. The V V wavelength list of van Deurzen shows a gap between 300 and 400 {angstrom}. The addition of our V IV lines fills this gap and provides an extensive list of accurate vanadium wavelengths suitable for reference standards throughout the vacuum wavelength region from 200-2000 {angstrom}.

Four-Function Calculator Used to Compute Wavelength Automatically

An inexpensive four-function calculator is being used to calculate on-line the wavelengths of spectral lines on photographic plates measured with an optical comparator. Although all precise wavelength calculations are made by fitting data to a polynomial equation in a computer program, it is often desirable to know quickly the wavelength of some spectral line or whether there is a line at some known region. An on-line wavelength calculation while the spectrum plate is still on the optical comparator and the spectral line or region is still in view greatly assists the operator.