Hyperfine Separation Research Articles

Two-photon spectroscopy of the francium8S1/2level

We report the spectroscopy of the 8S1/2 energy level in Fr by two-photon excitation of atoms confined and cooled in a magneto-optical trap. The resonant intermediate level is the upper state of either the 7P3/2 trapping transition or the 7P1/2 repumping transition. The center-of-gravity energy difference between the 7S1/2 ground level and the 8S1/2 level is 19 732.52360.004 cm . The hyperfine separation of the 8S1/2 ,F511/2 and F513/2 states is 1

Ground-state hyperfine-structure measurements of unstableEu+isotopes in a Paul ion trap

Hyperfine separations in unstable ${\mathrm{Eu}}^{+}$ ions of mass 148, 149, and 150 have been measured in laser-microwave double-resonance experiments in a Paul ion trap. In spite of the small available quantities of the isotopes, the experimental uncertainties are of the order of ${10}^{\ensuremath{-}8}$ or below, which is of the same order as in earlier measurements on stable isotopes of ${\mathrm{Eu}}^{+}.$ Extensive second-order perturbation calculation is required to obtain coupling constants for magnetic-dipole $(A)$ and electric-quadrupole $(B)$ interactions. The uncertainties are a few times ${10}^{\ensuremath{-}7}$ for $A$ and ${10}^{\ensuremath{-}3}$ for $B.$ The experiments are a step in an attempt to determine the differential hyperfine anomaly (Bohr-Weisskopf effect) in a long chain of isotopes.

Hyperfine structure measurements in the

Clouds of stable and unstable Eu+ isotopes have been confined in a Paul trap, each containing about 105 particles. In a microwave-optical double resonance experiment several hyperfine separations in the 4f7 6s 7S3 exited level have been measured with the experimental uncertainties ranging between 10-8 and 3×10-6. These experiments have confirmed that also in the case of an excited level with a large number of hyperfine or Zeeman sublevels the microwave-optical double resonance technique in a Paul trap can be useful for precise hyperfine structure investigation. The hyperfine coupling constants A and B have been determined for the isotopes 153Eu+, 151Eu+, 150Eu+ and 148Eu+. The results complement earlier measurements on the ground state of Eu+ and give additional information on the hyperfine anomaly in the Eu isotopic chain.

An ENDOR study of the canthaxanthin cation radical in solution

The cation radical of canthaxanthin was generated electrochemically in dichloromethane and its solution ENDOR spectrum is reported for the first time. The isotropic proton hyperfine coupling constants are in reasonable agreement with those calculated by RHF-INDO/SP molecular orbital methods for a planar all-trans-polyene conformation. Proton couplings less than 1.1 MHz were not detected due in part to incomplete hyperfine separation and chemical exchange processes.

Retardation corrections to the quarkonium hyperfine separations

The lowest order retardation corrections to the hyperfine separations are evaluated for some charmonium and bottomonium states under the usual assumption of a purely scalar Bethe-Salpeter confinement kernel. The form of the kernel and the parameters involved are the same used in a previous paper devoted to the evaluation of the leading spin-independent retardation corrections. Only the 1S and 2S states are considered. The corrections turn out to be about −30 MeV for the 1S separation and a few MeV for the 2S one.

Measurement of hydrogen hyperfine splittings as a test of quantum mechanics in a noninertial reference frame

Measurement of rotationally-induced splitting (in a magnetostatic field-free environment) of the hydrogen 1 2 S 1 2 (ƒ= 1; m ƒ = ± 1) hyperfine states provides a stringent test of the spin-dependence of the Hamiltonian of a bound two-particle system subject to global rotation. In addition, if the experimental uncertainty of 0.7 parts in 10 12 with which the hydrogen 1 2 S 1 2 (ƒ= 1)- 1 2 S 1 2 (ƒ=0) hyperfine separation can be currently determined in a hydrogen maser is reduced by two orders of magnitude, this fundamental atomic measurement can be affected by the rotation of the earth.

The coupled-cluster approach to non-relativistic and relativistic many-body calculations

A review is given of the atomic many-body theory in the coupled-cluster approach or exponential-Ansatz formulation. Explicit equations and corresponding graphical representations are given in the pair-approximation, where the one- and two-body parts of the cluster (exponent) operator are considered. Also the effect of a small, additional perturbation is considered. The technique of evaluating diagrams by means of one- and two-particle functions, satisfying inhomogeneous differential equations, is reviewed. Illustrative numerical results are given for the electron correlation energy, electron binding energy, hyperfine separation and specific mass shift of simple atomic systems. The extension of the non-relativistic procedure to the relativistic regime is discussed by considering the effect of the exchange of one and two virtual, transverse photons between the electrons. In lowest order this leads to the "no-virtual-pair approximation".

Precise ground-state hyperfine splitting in 173Yb II.

A laser-microwave double-resonance experiment on electrodynamically trapped $^{173}\mathrm{Yb}^{+}$ ions has been performed and a value of \ensuremath{\Delta}${\ensuremath{\nu}}_{\mathrm{h}\mathrm{f}\mathrm{s}=10\phantom{\rule{0ex}{0ex}}491\phantom{\rule{0ex}{0ex}}720239.55}$\ifmmode\pm\else\textpm\fi{}0.09 Hz for the ground-state hyperfine separation has been determined. This value is corrected for small Zeeman and second-order Doppler shifts. Combined with a previous similar measurement on $^{171}\mathrm{Yb}^{+}$ and with the known ${g}_{I}$ values of both isotopes, we obtain a value of -0.004 25(6) for the differential hyperfine anomaly $^{171}\mathrm{\ensuremath{\Delta}}^{173}$.

Relativistic kinematics and hyperfine separation in light and heavy mesons

A quark-antiquark potential is introduced which is a relativistic modification of the Richardson potential in the re-elaboration given the Schöberl. It is found that the hyperfine splitting of the spectrum of q- q can be reproduced both for light and heavy quarks in terms of a single scale parameter and the quark masses.

Detection of a hexadecapole interaction in the atomic ground state3 H 6 of167Er

Using the atomic beam magnetic resonance method, precision measurements of the hyperfine structure and Zeeman interactions have been performed in the ground state 4f 126s 2 3 H 6 of167Er. The experimental data were analyzed using an effective operator parametrized in the space of states of the ground state multiplet. It yielded eight effective hyperfine structure and Zeeman interaction constants which served to calculate the seven hyperfine separations of the ground state. The results are: $$\begin{gathered} 2F 2F' v_{FF'} (MHz) \hfill \\ 5 7 - 354.371 9409 (27) \hfill \\ 7 9 - 2{\text{78}}{\text{.231}} {\text{8263(14)}} \hfill \\ {\text{9}} 11 - 69.050 7785 (4) \hfill \\ 11 13 + 302.735 3731(12) \hfill \\ 13 15 + 866.691 3871(10) \hfill \\ 15 17 + 1,652.383 5154 (6) \hfill \\ 17 19 + 2,689.380 8050(10) \hfill \\ \end{gathered}$$ From the effective Zeeman interaction constants it was possible to determine an improvedg I -value, uncorrected for atomic diamagnetism: $$ g_I = + 0.086 775 (19) \cdot 10^{ - 3}$$ Furthermore a hexadecapole interaction corresponding to a diagonal hexadecapole interaction constant $$A_4 = - 16 (10) Hz$$ could be established which is of the order of magnitude expected from Coulomb excitation experiments as well as theoretical calculations.

Precise determination of the171Yb+ ground state Hyperfine separation

We performed a microwave-optical double resonance experiment on the ground state of171Yb+ ions. About 105 particles were confined in a r.f. quadrupole trap for periods of several hours in the presence of He buffer gas. Hyperfine pumping by a pulsed dye laser was followed by microwave transitions, which we observed via changes in the ionic fluorescence intensity. The ground state hyperfine splitting has been determined togD W=12642812124.2±1.4 Hz. The ultimate line width obtained in this experiment was 33 mHz, corresponding to a lineQ of 3.8·1011. The final error ofgD W is mainly determined by the accuracy of the available frequency reference.

Apparent hydrogen bonding by strongly immobilized spin-labels.

The hyperfine separations of nitroxide spin-labels which are tightly bound within hemoglobin exhibit a substantial temperature dependence even when the hemoglobin is immobilized by freezing or precipitation. It is shown that NO.--HX hydrogen bond formation by the spin-label within its binding site is a good explanation for the observed temperature dependence. Comparative studies using different hemoglobin derivatives and two different spin-labels suggest that the HX group may be some element of the protein matrix and that this hydrogen bond may be a factor in the stabilization of the label within its binding site. The hyperfine separation of a fatty acid spin probe incorporated into aqueous bilayer dispersons of dipalmitoylphosphatidylcholine also exhibits a temperature dependence at low temperature which is qualitatively similar to that of the spin-labeled hemoglobin systems. Saturation transfer electron paramagnetic resonance measurements indicate that label motion is not the source of this temperature dependence. A hydrogen-bond equilibrium between water molecules and the nitroxide NO. group appears to be a plausible source of the temperature-dependent hyperfine separation in the lipid bilayer system. Small amplitude torsional oscillation or librational motion by the nitroxide may also produce additional changes in the hyperfine separation which are difficult to distinguish from hydrogen-bonding effects under some circumstances. The apparent hydrogen-bond equilibrium exhibits a strong thermal and environmental dependence which may be of importance in a number of biophysical spin-label measurements.

A temperature-induced variation in the intrinsic hyperfine separation of a tightly bound nitroxide spin label

A temperature-induced variation in the intrinsic hyperfine separation of a tightly bound nitroxide spin label

Precision determination of the ground-state hyperfine separation inHg+199using the ion-storage technique

By an optical double-resonance experiment on $^{199}\mathrm{Hg}^{+}$, suspended in a rf quadrupole trap, we determined the ground-state hyperfine separation. Linewidths as small as 4 Hz have been observed. The final result of $\ensuremath{\Delta}{\ensuremath{\nu}}_{\mathrm{hfs}}=40507347997.8\ifmmode\pm\else\textpm\fi{}1.0$ Hz includes corrections to zero magnetic field and zero kinetic energy. The accuracy of the result and possible improvements lead to the feasibility of a new frequency standard in the microwave region.

Measurement of a Diamagnetic Shift in Atomic Hyperfine Structure

A diamagnetic shift in atomic hyperfine structure has been observed for the first time. The shift in the dipole hyperfine separation in $^{85}\mathrm{Rb}$ has been measured by a high-field laser optical-pumping technique and found to be 1.65(16)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}8}$ Hz/${\mathrm{G}}^{2}$. In addition, the nuclear- to electronic---$g$-factor ratio, $\frac{{g}_{I}}{{g}_{J}}$, has been determined to be - 1.466490 93(11) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$, independent of magnetic field.

Electron paramagnetic resonance study of Mn 2+ in ferroelectric lithium ammonium tartarate monohydrate

EPR studies of Mn 2+ in ferroelectric lithium ammonium tartarate monohydrate (LAT) show that there are four Mn 2+ complexes, which group themselves into two chemically different sets each containing two physically related sites at room temperature. It is inferred that Mn 2+ enters into NH 4 + site. The hyperfine separation of the central group ( 1 2 → − 1 2 ) is found to be constant, which is not observed usually. It is suggested that the space group of LAT below T c is P2 1.

The influence of cholesterol on molecular motion in egg lecithin bilayers—A variable-frequency electron spin resonance study of a cholestane spin probe

Electron spin resonance spectra at 9.5, 24. and 35 GHz were obtained for a cholestane spin probe in oriented multibilayers of egg lecithin of varying cholesterol content. In agreement with earlier studies, cholesterol induced a higher degree of spectral anisotropy in the multibilayers—the variation of the hyperfine separations with cholesterol content was in agreement with the model of Lapper et al. ( Can. J. Biochem. 50, 969 (1972)) where the amplitude of anisotropic probe motion decreased with increasing cholesterol content. Analysis of the electron spin resonance line shapes was done using the relatively simple modified Bloch equation approach, and correlation times for anisotropic probe motion were extracted from the spectra at three frequencies. The data demonstrate that increasing cholesterol content results in a decreased rate of anisotropic motion of the probe, providing further insight into the molecular mechanism of the condensing effect of cholesterol.

Fine and hyperfine structure in highly excited states of sodium

The technique of double photon absorption spectroscopy without Doppler broadening is used to measure the hyperfine separation interval in the excited 6S state and the fine structure interval in the excited 5D state of sodium vapor.

Hexadecapole interaction in the atomic ground state of165Ho

Using the atomic beam magnetic resonance method several hyperfine transitions in the ground state of165Ho were measured at magnetic fields near zero Oe. Including a hexadecapole interaction constantD a perfect fit of the seven hyperfine separations was possible giving the following results:A′=800.583645 (6)MHz,C′=−1.504 (37)kHzB′=−1668.00527 (33)MHz,D′=−0.137 (14)kHz. These interaction constants have been corrected for second order hyperfine interaction within the4I ground multiplet. The corrected constants are the following:A=800.583173 (36)MHz,C=−0.249 (140)kHzB=−1668.078 70 (330) MHz,D=−0.148 (16) kHz. Using a value for 〈r4f/−5〉Ho of Fraga a nuclear hexadecapole moment can be calculated:Π(165Ho)=0.89·10−48cm4. Because of severe uncertainties still present in the theory for calculating the electronic matrix elements this value can be only regarded as highly speculative.

Atomic Deuterium Maser

An atomic deuterium maser operating on hyperfine transitions was used to measure the ground-state hyperfine separation in deuterium. The result was ${\ensuremath{\nu}}_{0}(\mathrm{D})=327 384 352.5222(17)$ Hz where the hydrogen hyperfine frequency is assumed to be exactly 1420 405 751. 768 Hz. The construction of the device is discussed and a theory of the deuterium maser is presented with special attention given to frequency shifts occurring in the output frequency. In addition, a possible shift of the deuteron Larmor frequency because of the earth's gravitational field was also investigated and found to be ${10}^{\ensuremath{-}4}$ Hz.