Hfs Constants Research Articles

Heterodyne laser spectroscopy of lithium ions: 23 P fine and hyperfine structure of7Li+

The fine structure (fs) splittings in the 1s2p3PJ=1,2,0 multiplet of the helium-like7Li+ ion were measured with a laser spectrometer. The results with 3σ errors are: Δv01 (3P0,F=3/2−3P1,F=5/2)=152081.6(2.0) MHz and Δv02 (3P0,F=3/2−3P2,F=7/2)=82704.3(1.9) MHz. Combining the new precise fs measurements with earlier hyperfine structure (hfs) results from laser-microwave spectroscopy provided improved fs constants:D1=−155709.0(2.1) MHz,D2=−93049.2(2.0) MHz, and hfs constants:A c =3679.0(6) MHz,A0=51.0(4) MHz, andA d =−11.3(1) MHz, thus allowing for a stringent test of available theoretical data. The spectroscopic method used in this work opens up the possibility of determining Li+, 23S−23P absolute transition frequencies with a precision of ∼2·10−9.

Experimental and theoretical study of the hyperfine structure in the 4f75d6s6p configuration of Gd I.

A parametric hyperfine-structure (hfs) analysis of 24 excited even-parity levels of the 4${\mathit{f}}^{7}$5d6s6p configuration in Gd i was performed. The interpretation has been carried out based on a refined multiconfigurational fine-structure (fs) calculation taking altogether 177 assignments into account. The set of fs parameters as well as the leading eigenvector percentages of levels relevant for this paper are given. SL-limit effective-operator expressions are presented for the magnetic-dipole and electric-quadrupole hfs of arbitrary states built from four open electron shells. The following single-electron hfs parameters ${\mathit{a}}_{6\mathit{s}}^{10}$ and ${\mathit{b}}_{6\mathit{p}}^{02}$ were deduced for $^{155}\mathrm{Gd}$, ${\mathit{a}}_{6\mathit{s}}^{10}$=-1270(22) MHz, ${\mathit{b}}_{6\mathit{p}}^{02}$=1507(26) MHz and for $^{157}\mathrm{Gd}$, ${\mathit{a}}_{6\mathit{s}}^{10}$=-1668(28) MHz, ${\mathit{b}}_{6\mathit{p}}^{02}$=1603(29) MHz. For the odd-parity level 4${\mathit{f}}^{7}$5d6${\mathit{s}}^{2}$ $^{7}$${\mathit{D}}_{4}$ the magnetic-dipole A and electric-quadrupole B hfs constants were found to be $^{155}$A=-11.3(2.1) MHz, $^{155}$B=54(9) MHz, $^{157}$A=-14.8(2.7) MHz, and $^{157}$B=58(10) MHz. The validity of all single-electron hfs parameters was checked using general trends of the corresponding 〈${\mathit{r}}^{\mathrm{\ensuremath{-}}3}$${\mathrm{〉}}_{\mathit{n}\mathit{l}\mathit{s}}^{\mathit{k}}$${\mathit{k}}_{\mathit{l}}$ values known for the series of the lanthanides. Finally, the evaluation of the electric nuclear quadrupole moment is discussed.

Hyperfine-structure studies of Zr II: Experimental and relativistic configuration-interaction results.

We report an experimental and theoretical study of the hyperfine structure (hfs) in various metastable levels in $^{91}\mathrm{Zr}$ ii. Hyperfine structures in 11 levels arising from the 4${\mathit{d}}^{3}$ and 4${\mathit{d}}^{2}$5s configurations were measured using the laser-rf double-resonance method in a collinear laser--ion-beam geometry. The hfs A and B constants were measured to a precision of 4 and 11 kHz, respectively. Less precise values for hfs constants for nine upper levels in the 4${\mathit{d}}^{2}$5p configuration were derived from optical spectra. Theoretically, the A and B constants for the metastable levels having J=0.5 and 1.5 were calculated using a relativistic configuration-interaction (RCI) approach. The final many-body wave function produced energy gaps between the five J=0.5 levels which differ from experiment by an average of 0.050 eV, whereas the corresponding value for the ten J=1.5 levels is 0.087 eV. For the two J=0.5 levels measured and calculated, the average error in A is 31.8%. For the three J=1.5 levels, the situation is better, with the average error in A being 9.2%. For comparison, the average errors in A using independent-particle Dirac-Fock (DF) wave functions were 88% and 136% for J=0.5 and 1.5, respectively. In all cases, the many-body (RCI) result represents a vast improvement from the DF result for the A values. The value for the electric-quadrupole moment of $^{91}\mathrm{Zr}$ obtained from a comparison of the experimental B values and theoretical matrix elements is 0.257(0.013) b. In addition, the calculations confirm a previous report that the level at 17 614.00 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ reported in Moore's Atomic Energy Levels, Vol. II (U.S. Government Printing Office, Washington, D.C., 1971) is spurious.

Radical ions and germyloxyaminoxyls from nitrospiro[indoline-naphthopyrans]. A combined electrochemical and EPR study

The radical ions from 5-nitrospiro[indoline-2,3′-naphthopyran]1, 8′-nitrospiro[indoline-2,3′-naphthopyran]2, and 5,8′-dinitrospiro[indoline-2,3′-naphthopyran]3 have been investigated electrochemically and by means of electron paramagnetic resonance spectroscopy.The first reduction potentials of these compounds reflect the position of the nitro groups and vary between –1.532 V for 1 and –1.273 V for 2vs. SCE, while 3 exhibits two reduction waves at, potentials similar to those of 1 and 2, suggesting no or very little interaction between the two moieties of the molecules. The oxidation potentials are dominated by the indolinic moiety increasing in the order 2 < 1 < 3.The reduction with butoxide in DMF leads to the EPR observation of the expected radical anions of 1 and 2, while the spectrum observed with 3 shows, against expectations, reduction of the indolinic moiety. Photoreduction with Bu4NBH4 in THF affords the radical anions of 2 and 3 but not of 1, the measured hfs constants being similar to those measured in DMF without light. Addition of in situ generated triphenylgermyl radicals to 1–3 affords rather persistent germyloxy-aminoxyls which give identical spectra both under UV irradiation and in the dark.

Hyperfine structure of odd-parity levels in 139LaI by laser optogalvanic spectroscopy

The hyperfine structure (hfs) of eight odd-parity levels of 139LaI has been studied by high-resolution Doppler-limited laser optogalvanic spectroscopy. The magnetic-dipole hfs constants A are obtained by least-squares fits. The A values of five of these levels are reported for the first time to our knowledge. One A value of the three previously reported levels is corrected, and the other two are also given for comparison where the agreements are good.

Laser-rf double-resonance measurements of the hyperfine structure in 49Ti II.

The hyperfine structures of six metastable levels arising from the 3{ital d}{sup 2}4{ital s} and 3{ital d}{sup 3} configurations in {sup 49}Ti II have been measured with high precision using the laser-rf double-resonance technique in a collinear laser--ion-beam geometry. The hfs constants {ital A} and {ital B} were determined to about 4 and 43 kHz, respectively. Less precise results are also reported for the 2{ital p}{sub 1/2} level of the 3{ital d}{sup 3} configuration and for five upper levels in the 3{ital d}{sup 2}4{ital p} configuration. For these states, the optical spectra had Doppler widths of about 40 MHz, leading to {ital A} values determined to about 1 MHz. The results are compared with the presently available Hartree-Fock (HF) calculations. Good agreement is obtained with the HF results only in some cases. Substantial corrections due to many-body interactions and relativistic effects are required for other cases.

Experimental and theoretical study of the hyperfine structure in the lower configurations in 45Sc II.

We have measured the hyperfine structure (hfs) of 12 levels in the configurations 3d4s, 3${\mathit{d}}^{2}$, and 3d4p in singly ionized scandium by collinear fast-ion-beam--laser spectroscopy. The hfs of the four levels in the configuration 3d4s has to our knowledge not been measured before. From these levels the ions were excited to levels in the 3d4p configuration by the frequency-doubled output of a ring dye laser with an intracavity mounted ${\mathrm{LiIO}}_{3}$ crystal. Levels in the 3${\mathit{d}}^{2}$ configuration were excited to levels in the 3d4p configuration with visible laser light. The resulting magnetic dipole (A) and electric quadrupole (B) hfs constants are analyzed in Sandars-Beck effective-operator formalism. The multiconfiguration Dirac-Fock method has been used to calculate the hfs constants for levels in the configurations 3d4s, 3d5s, 3d6s, 3${\mathit{d}}^{2}$, and 3d4p. Within the framework of the configuration-interaction method, an approach is presented for the calculation of the core polarization, which uses a virtual basis set localized inside the core. For all levels, this approach gives better results compared to previously published calculations.

Radical cations of cis- and trans-1,3-di- and 1,3,5-trimethylcyclohexanes. Matrix influence on two nearly degenerate SOMOs

Radical cations of cis and trans isomers of 1,3-di- and 1,3,5-tri-methylcyclohexane, stabilized in various γ-irradiated solute–halocarbon matrices at 77 K and above, have been investigated by means of EPR spectroscopy. The hfs constants have been compared with those calculated using semiempirical methods, INDO (spin density) and MNDO (geometry optimizations). The SOMOs of the methyl-substituted cyclohexane cations are all similar to either of the orbitals, ag or bg, following a Jahn–Teller split of the eg orbital (HOMO) of cyclohexane. The selection of SOMO depends on matrix and isomer. The trans isomers have one axial methyl group and the cations were found to take an ag-like SOMO in all matrices used, with large spin density on the equatorial hydrogen attached to the axially substituted ring-carbon. Using CF3CCl3 as matrix the EPR signal due to the trans-1,3,5-trimethylcyclohexane cation contains (in addition) a spectrum of the bg-like SOMO superimposed. The cation of cis-1,3-dimethylcyclohexane shows contributions from both SOMOs in the matrices CF3-cC6F11, CF2ClCFCl2 and CF3CCl3, but exclusively a bg-like SOMO in cC6F12. A bg-like SOMO is observed for the cis-1,3,5-trimethylcyclohexane cation in all matrices. The abundance ratios, [ag]/[bg], for the cases where the matrix-stabilized cation shows contribution from both bg- and ag-like SOMOs simultaneously, are found to be ca. 1/4 from line shape simulations. No prominent temperature dependence of this ratio is detected.

J off-diagonal effects in the hyperfine-structure splitting in the Eu I term e6D of 4f76s6d.

In the analysis of high-resolution Doppler-free two-photon hyperfine-structure (hfs) measurements of levels in the Eu i term $^{6}\mathrm{D}$ of the configuration 4${\mathit{f}}^{7}$6s6d of $^{151}\mathrm{Eu}$ and $^{153}\mathrm{Eu}$ the necessity occurs to take into account also hfs perturbations. For the magnetic hfs interactions of $^{151}\mathrm{Eu}$, the following off-diagonal matrix elements $^{151}$${\mathit{A}}_{1}$(JJ') could be determined from the high-resolved two-photon line profiles: $^{151}$${\mathit{A}}_{1}$(1/2,3/2)=5.70(3) GHz, $^{151}$${\mathit{A}}_{1}$(3/2,5/2)=4.3(2) GHz, $^{151}$${\mathit{A}}_{1}$(5/2,7/2)=2.9(2) GHz, $^{151}$${\mathit{A}}_{1}$(7/2,9/2)=2.2(2) GHz. The high quality of the calculations is represented both in the reproducibility of the absolute hfs level energies and also in the hfs anomaly where a mean value deduced from the corrected magnetic hfs constants of -0.66(8)% can be stated.

Orthorhombic Eu2+centre in Ca1-xBaxF2crystals

Abstract Eu2+ complex centre in Ca1-xBaxF2 crystals was studied with different values of x. And a new kind of ESR centre attributed to Eu2+-Ba2+ complex was found at room temperature. The determined spin Hamiltonain parameters are g=1.995 + -0.001, B0 2 = 117.6(G), B2 2 = 16.1(G), B0 4 = 0.24(G), B2 4 = 4.63(G), and B4 4= -3.47(G). Approximate hfs constants are |A151| = 37(G) and |A153| = 16.4(G), respectively. The ESR signals grew with x, but the fine structure spectra were broadened and finally disappeared as well as usual cubic Eu2+ ones.

M1, E2, and M3 hyperfine structure and nuclear moment ratios for 151,153Eu.

The atomic-beam laser-rf double-resonance technique has been used to obtain precise values for the hyperfine structure (hfs) splittings in ten 4${\mathit{f}}^{7}$5d6s $^{10}$${\mathit{D}}_{\mathit{J}}$ and $^{8}$${\mathit{D}}_{\mathit{J}}$ levels of $^{151,153}\mathrm{i}$. Detailed studies of the second-order hfs lead to the isotopic ratios of the hfs constants, and reveal surprisingly strong hfs interactions between the two multiplets. The dipole ratios, when compared with the known ratio of the nuclear dipole moments, reveal striking J- and term-dependent hyperfine anomalies. The quadrupole ratios (after corrections for the second-order hfs) are consistent with the atomic ground-state value and self-consistent among the ten levels studied. The precision of the measurements allows evaluation of the ratio of the magnetic octupole hfs interaction constants between the two isotopes. The result, which is taken to be the ratio of the nuclear ground-state magnetic octupole moments \ensuremath{\Omega}, is found to be \ensuremath{\Omega}${(}^{151}$Eu)/\ensuremath{\Omega}${(}^{153}$Eu)=0.87(6).

Hyperfine structure of high-L states in 143,145Nd I by atomic-beam laser-rf double resonance.

The atomic-beam laser-rf double-resonance technique has been used to study the hyperfine structure (hfs) of the metastable {sup 7}{ital L}{sub 5--11} and {sup 7}{ital K}{sub 4} states of the 4{ital f}{sup 4}5{ital d}6{ital s} configuration in {sup 143,145}Nd I. Four zero-field intervals were measured in each state and the results used to assign the conventional hfs constants {ital A} and {ital B}. Comparison of the results with predictions of the Sandars-Beck model allowed evaluation of the relevant single-electron radial hfs integrals. These are compared with earlier results from the Nd I atomic ground term and with extrapolations from other rare-earth elements. The unusually large orbital-angular-momentum values ({ital L}=7 and 8 for the states studied) do not appear to have introduced any anomalous effects. {ital Ab} {ital initio} calculations are not yet feasible for the complex 4{ital f}{sup 4}5{ital d}6{ital s} levels studied.

Hyperfine structure measurements of 235U High-Lying Levels Using a Hollow-Cathode Lamp

The hyperfine structure (hfs) of three 235U high-lying levels has been measured by using a hollow-cathode lamp and laser-induced fluorescence technique. These transitions are from the first excited states at 16900 and 16505 cm-1 to the higher excited states. From the measured spectra, the isotope shifts and hfs widths for these levels are determined, and the hfs constants A and B for two levels are obtained.

Effect of polar medium on the hfs constants of the H 2NO . radical: Ab initio continuum model study

The aim of this study was to consider the applicability of the quantum chemical ab initio version of the continuum model of solvation to the investigation of the constants of the hyperfine interaction of radicals in polar media

Doppler-free laserspectroscopic investigations of hyperfine structure in the atomic cobalt spectrum

Performing Doppler-free laserspectroscopic investigations in the red wavelength region (640–670 nm) we were able to determine 10A-factors and 9B-factors of atomic cobalt levels. Now precise values of 18A-factors and 16B-factors of levels belonging to the configurations (3d+4s)9 are known. Fitting of the one-electron radial parameters to introduce agreement between experimental and theoretical hfs constants allows the prediction of hfs constants of not yet investigated fine structure levels. Values of the electric quadrupole moment of the Co59 nucleus are determined in two electron configurations. The resulting mean value of the spectroscopic quadrupole moment isQ=0.35(3) barn.

Electron Spin Resonance Spectra of Sulfinamidyl Radicals and a Comparison of Hyperfine Splitting Constants with Sulfenamidyl and Sulfonamidyl Radicals

Abstract An ESR spectroscopic study of N-arylsulfinyl- and N-alkylsulfinyl-3,5-di-t-butylphenylaminyls (2) is described. The sulfinamidyls 2, generated by the reaction of the corresponding sulfinamides (7) with di-t-butyl diperoxyoxalate (DBPO) in benzene at 21 or 40°C, give hyperfine splitting (hfs) constants which indicate that the unpaired electron is slightly delocalized onto the sulfinyl group. A comparison of the hfs constants for 2 with those for structurally related sulfenamidyl and sulfonamidyl radicals indicates that the abilities of –SR, –S(O)R, and –S(O2)R to delocalize the unpaired electron are in the order –SR&amp;gt;–S(O)R&amp;gt;–(O2)R. The reaction of 7 with DBPO has been examined on the basis of product analyses. The mechanism accounting for the formation of the isolated products is briefly discussed.

Hyperfine structure for some vacuum ultraviolet lines of Tl II and Tl III

The thallium spectrum has been observed in the 1300–2000 Å region using sliding spark and triggered spark excitation sources. Hyperfine structure (hfs) splittings have been reported for 17 Tl II lines and 2 Tl III lines. This leads to the confirmation of the earlier analysis of Tl II in our region of observation. Revised level values for the levels of the 5d106s6p, 5d106s7s, 5d106s6d, and 5d106p2 configurations are also reported. A new value of the hfs constant A for 6s6p 3P1 in Tl II has been reported. Tentative values for the hfs constant A for 6s 2S1/2 and 6p 2P1/2,3/2 in Tl III have been suggested.

Sternheimer free determination of the51V nuclear quadrupole moment from hyperfine structure measurements

The hyperfine structure (hfs) of 18 metastable states of51V has been measured by laser induced fluorescence. 15 of these states have been measured additionally very precisely by the ABMR-LIRF method. Using results of earlier hfs measurements, the hfs of altogether 33 fine structure states is analyzed using a method of simultaneous parametrization of one- and two-body interactions in the atomic hfs of the model space 3d3 +M 4s2 −M (M = 0, 1, 2). The hfs of these states is described by 16 parameters for the magnetic dipole interaction and 12 parameters for the electric quadrupole interaction. From these model space parameters corresponding configuration dependent parameters for the three configurations were determined. These parameters allow a prediction of the hfs constants of all states of the modelspace within an accuracy of 5 to 10%. The evaluation of the nuclear quadrupole moment of51V, free of Sternheimer corrections up to second order, yielded the value of -0.043(5) barn.

Spin Distribution in the Phenyldiazenyl Radical

Abstract Hyperfine coupling constants of carbons in the benzene ring of phenyldiazenyl radical were determined. The high hfs constant of C-1, 62.2 G, is a characteristic nature of phenyldiazenyl.

Hyperfine structure of Sc II: Experiment and theory.

Collinear laser--ion-beam spectroscopy has been used to measure hyperfine structure (hfs) in three levels of the 3${d}^{2}$ and six levels of the 3d4p configuration of Sc ii. The results combine with earlier measurements of hfs within these configurations to give a fairly complete picture of hfs in these configurations. The combined results are compared with multiconfiguration Dirac-Fock (MCDF) ab initio calculations. Good agreement is obtained for the magnetic dipole hfs constants of the singlet states in both the 3${d}^{2}$ and 3d4p configurations, but the MCDF predictions for the triplet states are not even qualitatively correct. The poor agreement for the triplet states appears to be due to the neglect of core polarization in the present MCDF approach.