Isotope Shift Data Research Articles

High-resolution laser system for the S[formula omitted]-Low Energy Branch

In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S3-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S3. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the 4f126s23H6→4f12(3H)6s6pJ= 5 atomic transition (415 nm) and the tin isotopes were studied by the 5s25p2(3P0)→5s25p6s(3P1) atomic transition (286.4 nm), and are used as a benchmark of the laser setup. Additionally, the tin isotopes were studied by the 5s25p6s(3P1)→5s25p6p(3P2) atomic transition (811.6 nm), for which new isotope-shift data was obtained and the corresponding field-shift F812 and mass-shift M812 factors are presented.

Isotope shift measurements in 555-833 nm wavelength region with FTS and electronic configuration assignments to the energy levels of neutral dysprosium atom

Precise spectroscopic measurements of isotope shift (IS), Δσ (160Dy - 164Dy) have been carried out in the 258 atomic emission lines of neutral dysprosium covering 555–833 nm wavelength region, of which IS data for 198 lines is being reported for the first time. The present measurements have contributed significantly to understanding the complex Dy I atomic structure, which enabled us to report the level isotope shift, ΔT (160Dy - 164Dy) for 100 even- parity and 82 odd- parity energy levels out of which ΔT (160Dy - 164Dy) values for 45 even- and 36 odd- parity levels are new. Earlier tentative assignments of 15 even levels to 4f95d6s6p and 5 even- levels to 4f106s6d configuration have been confirmed in the present study. New configuration assignments have been made to 10 even levels and also 5 each assigned to 4f95d6s6p and 4f106s6d configurations. The validity of 10 odd-parity energy levels theoretically assigned earlier to the mixed (4f95d6s2+4f106s6p+4f95d26s) configurations has been verified using newly derived experimental level isotope shifts, ΔT (160Dy-164Dy) values. Tentative assignments of 4f105d6p configuration confirmed for the 5 odd levels lying between 35029.50 cm−1 (J=8) - 37836.50 cm−1 (J=9). The present investigations have led to the first identification of two almost pure levels of 4f105d6p configuration at 35777.79 cm−1 (J=8) and 36260.17 cm−1 (J=9). The ΔT (160Dy- 164Dy) values for 2 levels of 4f106s7p configuration have been evaluated by us for the first time, whose configuration assignments have been confirmed presently.

Resonance ionisation spectrometry measurement of atomic calcium Rydberg isotope shifts

Rydberg levels in atomic calcium are of interest due to their use in highly isotope selective multiple-step resonance ionisation spectrometry, and also for nuclear physics investigations, but gaps remain in the data for higher lying levels in calcium isotopes other than . We report novel isotope shift data on four isotopes of calcium (, , , ), relative to the majority abundance isotope , in six Rydberg transitions for each P (n = 25–30) and F (n = 23–28) angular momentum quantum number designated series.

Isotope shift measurements in the 660 spectral lines of Er I covering the 340–605 nm wavelength region with a Fourier Transform Spectrometer

Isotope shift measurements in 660 spectral lines covering the 340–605nm wavelength region of Er I were carried out using a Fourier Transform Spectrometer. The spectra were recorded using a liquid nitrogen cooled hollow cathode discharge source containing highly enriched 166Er and 170Er isotopes in the oxide form and two different detectors namely PMT and silicon photo diodes. Out of 660 spectral lines involving 216 even and 182 odd Er I levels, the isotope shift data were new in the 406 lines. On the basis of their level isotope shifts out of 114 unassigned even parity levels 27 levels assigned to 4f116s26p, 72 to 4f115d6s6p and 15 to 4f126s6d configuration whereas 12 each of unassigned odd parity levels assigned to 4f115d6s2, and 4f126s6p configurations and 16 unassigned odd parity levels assigned to 4f115d26s configuration. Configuration mixing for 30 odd parity energy levels has been theoretically calculated applying ‘Sharing Rule’ to the experimentally derived level isotope shifts, which were finally compared with mixings available in the literature.

High resolution laser spectroscopy of naturally occurring ruthenium isotopes

High resolution crossed atomic beam laser spectroscopy has been used to measure isotope shifts and hyperfine structures in 12 transitions in naturally occurring ruthenium isotopes. Improved values for the changes in mean square charge radii have been deduced from a combined analysis of optical isotope shift and muonic x-ray data.

Hyperfine structure and isotope shift analysis of singly ionized titanium

The even-parity low configuration system of Ti II has been considered on the basis of the experimental data found in the literature, and its fine structure has been reanalyzed by simultaneous parameterization of one- and two-body interactions for the model space (3d + 4s)3. Furthermore, the main one-electron hyperfine structure parameters for these configurations have been evaluated. For instance, for 3d24s1, and . Field shifts (FS) and specific mass shifts (SMS) of the main Ti II configurations are deduced by means of ab initio estimates combined with a small quantity of experimental isotope shift data available in the literature: FS(3d3) = −63.3 MHz, FS(3d24p1) = −49.7 MHz, FS(3d14s2) = 98.2 MHz, FS(4s24P1) = 163.4 MHz and SMS(3d3) = 1453.3 MHz, SMS(3d14s2) = −2179.7 MHz, …, referred to 3d24s1 for the pair Ti46–Ti48.

Experimental Studies on Electronic Configuration Mixing for the Even-Parity Levels of Gd I Using Isotope Shifts Recorded in the Visible Region with FTS

Electronic configuration (4f6s6p + 4f5d6s6p + 4f5d6p) mixing studies in the high even-parity energy levels of Gd I spectrum have been carried out on the basis of isotope shift (IS) Δσ156,160 data recorded in 49 spectral lines partially in the visible wavelength region on Fourier Transform Spectrometer (FTS) and the relevant spectral line IS data available in the literature. We employed “Sharing rule” to the experimentally observed level isotope shifts (LIS) of the even-parity levels for finding the percentage composition of each configuration being mixed. An FTS spectrum of Gd I in the region of 365–495 nm acquired employing the highly enriched Gd isotopes in liquid nitrogen cooled hollow cathode lamp (HCL) as a light source and photomultiplier tube as the detector. The studies of altogether 48 even-levels have revealed that amongst the 20 high even parity levels assigned previously to>95%4f5d6s6p configuration, 10 levels have agreed verywell whereas 7 have exhibited large contribution of 4f5d6s6p configuration compared to 4f5d6p configuration and 3 levels have equal contribution of 4f5d6s6p and 4f5d6p configurations. Out of 8 unassigned levels, 6 have dominant 4f5d6s6p configuration compared to 4f5d6p configuration and the remaining two have dominancy in 4f5d6p configuration.

Charge radii of radium isotopes

We present a combined analysis of the available isotope-shift data from the optical spectra of Ra atoms and Ra${}^{+}$ ions. Atomic structure calculations of the field-shift and specific mass-shift constants of the low-lying levels in Ra${}^{+}$ are used. The nuclear radial differences $\ensuremath{\delta}\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}$ for the radium isotopes are derived and compared to previous analyses and nuclear models. We discuss the relevance of our results to measurements of atomic parity violation in a chain of Ra${}^{+}$ isotopes.

Semiempirical hyperfine structure and ab initio isotope shift predictions in Zr II

The fine structure of the even-parity low configurations has been reanalyzed by simultaneous parameterization of the one- and two-body interactions for the model space (4d + 5s)3. Using the calculated eigenfunctions, the magnetic-dipole A hyperfine constants for the whole 37 existing levels of the model space were predicted and compared partially to those obtained using relativistic configuration-interaction approach. Moreover, volume shifts (VS) and specific mass shifts (SMS) of numerous configurations of singly ionised zirconium are deduced by means of ab initio estimates combined with a few experimental isotope shift data available in literature: VS(4d15s2) = 840 MHz, VS(4d3) = −649 MHz, VS(4d15p2) = −387 MHz, VS(5s25p1) = 1250 MHz, and SMS(4d15s2) = −634 MHz, SMS(4d3) = 484 MHz, SMS(5s25p1) = −1459 MHz, referred to 4d25s for the pair Zr90–Zr92. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Fourier transform high-resolution spectroscopic studies of Gd I: optical isotope shifts in the spectral region of 18 700–20 200 cm−1

Isotope shift (IS) measurements in 67 spectral lines were carried out for the neutral gadolinium atom in the wavelength region of 4950–5350 Å using a BOMEM DA8 Fourier transform spectrometer with a liquid-nitrogen-cooled hollow cathode lamp as a source and a photomultiplier tube as the detector. The present investigation provided experimental IS data in 44 lines for the first time. Out of 53 high even levels encountered in the studies, level ISs have become available for 13 for the first time. The study also contributed to confirmations of previously assigned 4f75d6s6p, 4f75d26p and 4f85d6s configurations for some of the even-parity energy levels. Strong configuration interaction has been observed in the few high even-parity levels pertaining to 4f75d6s6p and 4f75d26p configurations.

Changes in the mean square charge radii of neutron-deficient europium isotopes measured by the laser ion source resonance ionization spectroscopy

The laser ion source has been used for the study of the isotope shifts of neutron-deficient Eu isotopes. The extension of the region of applicability of the method by using the $\gamma $ - and $\beta$ -radiation detection is reported. We have measured the isotope shifts of the europium optical line 576.520 nm for $^{137\mbox{--}139,141,142m,143,144}{\rm Eu}$ . To increase the laser ion source efficiency an axial magnetic field (350 gauss) was applied. Nearly a twofold rise of the ionization efficiency for Eu was observed. By using the effect of optical ion bunching an increase of the selectivity was obtained. The isotope shift data for $^{139,141,142m,143,144}{\rm Eu}$ are in agreement with the previously measured isotope shifts for these nuclides. The new data for $^{137}{\rm Eu}$ and refined data for $^{138}{\rm Eu}$ point to a gradual increase of the deformation for these isotopes. Comparisons with microscopic-macroscopic calculations and calculations in the framework of the Hartree-Fock model were performed.

Isotope shift studies in UV lines of Sm I on FTS: level isotope shifts and configuration assignments of the energy levels of neutral samarium atom

Isotope shifts $\Delta \sigma^{148,154}$ in 200 spectral lines of neutral samarium atom (Sm I) in the region of 355-455 nm (28160-21970 cm-1) have been measured using a Fourier Transform Spectrometer. Isotope shift data in 187 spectral lines of Sm I are being reported for the first time. Level isotope shifts, $\Delta T^{148,154}$ of 119 high odd- and 7 low even-parity energy levels have been evaluated using present isotope shift data combined with the earlier available data. These $\Delta T^{148,154}$ values have enabled us to check the assignments to 4f 66s6p and 4f 55d6s 2 configurations of the odd-parity levels made earlier on the basis of parametric calculations. For several levels, the reported compositions of the mixed configuration of type [4f 5(6H0, 6F0) 5d6s 2 + 4f 6(7F) 6s6p(3P0)] have been interpreted with the help of our $\Delta T^{148,154}$ values. 20 unassigned energy levels have been uniquely assigned to 4f 55d6s 2 configuration. The present study provides $\Delta T^{148,154}$ values of the levels, which were tentatively assigned to 4f 55d 26s and 4f 65d6p configurations. We could also identify 4f 65d6p configuration for 12 unassigned levels.

Infrared absorption spectroscopy of the CnXe (n = 2, 3, 5, 7, 9) species

CnXe (n = 2, 3, 5, 7, 9) compounds, generated by pulsed laser evaporation of a carbon pellet or by the electrical discharge of acetylene, have been deposited in an argon matrix at 12 K and studied by Fourier transform infrared absorption spectroscopy. Five new vibrational bands at 1774.2, 2033.3, 2161.4, 2126.6 and 1997.2 cm−1 have been observed. Using ab initio MP2 theoretical methods, the first two bands have been assigned to the fundamental stretching modes of C2Xe and C3Xe, respectively. These assignments are supported by 13C isotopic shift data. The C–Xe bond in C2Xe is predicted to be stronger than in C3Xe. Although bent C3Xe is a little more stable than linear C3Xe, both species have very flat potential surfaces and both may exist in Ar matrices. The latter three bands are tentatively assigned to C–C asymmetric stretches in C5Xe, C7Xe, and C9Xe, respectively. Despite the lack of isotopic data for these species, this assignment is reasonable based on the smooth frequency shift for the CnXe species compared to the Cn species.

Fine-structure analysis of the odd-parity Rydberg series of Zr I

A fine-structure (fs) analysis of the odd-parity Rydberg series of atomiczirconium, including the main low-lying mutually interacting configurations, hasbeen performed for the first time, with the aid of a linked-parameter method oflevel fitting. A set of derived fs parameters, together with ab initio valuescalculated for comparison, and the leading eigenvector percentages ofthe levels were obtained. Many of the levels belonging to the 4d25s5p, 4d5s25p and4d35pconfigurations are found to be incorrectly assigned. To confirm this majorrevision, specific mass shifts deduced from experimental isotope shiftdata available in the literature have been used as fingerprints. Finally, acomplete set of predicted magnetic dipole and electric quadrupole hyperfinestructure constants has been calculated for the known odd-parity levels inzirconium.

The other high-temperature superconductors

Since the discovery of the high-temperature superconducting cuprates in 1986, there have been four classes of superconductors discovered that have members with critical temperature higher than the highest known in 1986. These classes are typified by (in chronological order) the representatives: Ba 1− x K x BiO 3, Cs 3C 60, YPd 2B 2C, and Na x HfNCl, with maximum critical temperatures, respectively, of 35, 40, 23, and 25 K. These new superconductors are mostly different from the older superconductors, and certainly different from the layered cuprates. For several characteristics that are possibly important for superconductivity, two or three of the classes share similarities. There seems, however, to be almost no feature that is shared by all four classes. However, the three for which there is isotope shift data clearly qualify as phonon-coupled superconductors.

Reevaluation of term isotope shifts of low even levels of 4f 86s 2 configuration and high odd-parity levels of neutral gadolinium atoms

Isotope shift Δ T( 156Gd– 160Gd) of the even-parity energy levels of 4f 86s 2 and 4f 76s 26p configurations of neutral gadolinium atoms (Gd I) have been reevaluated using the level isotope shift (Δ T) of two odd-parity levels reported recently. Earlier the isotope shifts of these even-parity energy levels were evaluated using empirical relation. Our extensive isotope shift data has been used for the reevaluation of Δ T values of these low even-parity energy levels which have been utilised for revision of the Δ T values of high-lying odd-parity energy levels of Gd I.

Hydroxyl group interactions in polysaccharides: a deuterium-induced differential isotope shift 13C-NMR investigation.

The secondary isotope shift in (13)C-nmr spectra in water was used to obtain information on the interactions of hydroxyl groups with their environment in polysaccharides. Specifically, the possibility of detecting the preference of intramolecular hydrogen bonding with respect to solvation was investigated. Different aliphatic alcohols were studied in both protic and aprotic solvents in order to obtain reference systems. The polysaccharides investigated were selected so as to include both different types of glycosidic linkages and different conformational properties of the polymeric chain. In addition to polysaccharides, beta-cyclodextrin and inulin were also investigated. The experiments demonstrated that isotope shift data can advantageously contribute to the understanding of the conformational properties of polysaccharides and in particular, in setting up of constraints in molecular modeling calculations.

On the identification of the vibrational spectrum of cyclic C8 in solid Ar

A recent proposal to assign or reassign absorptions in Fourier transform infrared spectra of the products of evaporating graphite trapped in argon matrices to linear C13 and cyclic C8 has been examined. An analysis of the experimental and theoretical data presented indicates that the claimed identification of linear C13 is unwarranted. Simulations of spectra based on density functional theory calculations and isotopic shift data indicate that an absorption at 1818.0 cm−1 belongs to a carbon chain, and do not support a revision of our earlier identification of the ν12(eu) fundamental of cyclic C8 at 1844.2 cm−1.

Resonance Raman characterization of five-coordinate dioxygen adducts of porphyrinatocobalt(II) complexes formed in low temperature O2 matrices

Resonance Raman (RR) spectra of five-coordinate dioxygen adducts of cobalt(tetramesitylporphine) and cobalt(tetramesopropylporphine) formed in low temperature O2 matrices are reported. For the first time, all three vibrations expected for the Co–O2 fragment, ν(O–O), ν(Co–O2) and δ(Co–O–O), were observed for 16O2 and 18O2 isotopomers. These bands have been assigned based on oxygen isotope shift data as well as normal coordinate analysis of the Co–O2 moiety. This work presents also the first observation of two distinct ν(O–O) bands due to the Co–16O–18O and Co–18O–16O isomers in ‘end-on’ type dioxygen adducts. The mechanism of resonance enhancement, the effect of the axial ligand on the ν(O–O) and ν(Co–O2) frequencies and the differences in metal–O2 bonding between cobalt and iron porphyrins are discussed.

Spectroscopic investigation of Li1+xV3O8

The room temperature Raman spectra of Li1.1V3O8 and 6Li1.1V3O8, both prepared as single crystals, have been measured in several scattering geometries. Infrared spectra of these compounds have also been recorded. The spectral data are discussed in terms of a symmetry-based factor group analysis. Isotopic shift data allow the identification of bands containing significant amounts of lithium ion motion. The spectrum of Li4V3O8 is also reported and discussed; these data are useful in identifying the effects of lithium intercalation on the vibrational spectrum of Li1.1V3O8.