Atomic Beam Measurements Research Articles

Remote frequency measurement of the 1S0 → 3P1 transition in laser-cooled 24Mg

We perform Ramsey–Bordé spectroscopy on laser-cooled magnesium atoms in free fall to measure the 1S0 → 3P1 intercombination transition frequency. The measured value of 655 659 923 839 730 (48) Hz is consistent with our former atomic beam measurement (Friebe et al 2008 Phys. Rev. A 78 033830). We improve upon the fractional accuracy of the previous measurement by more than an order of magnitude to 7 × 10−14. The magnesium frequency standard was referenced to a fountain clock of the Physikalisch Technische Bundesanstalt (PTB) via a phase-stabilized telecom fiber link and its stability was characterized for interrogation times up to 8000 s. The high temperature of the atomic ensemble leads to a systematic shift due to the motion of atoms across the spectroscopy beams. In our regime, this leads to a counterintuitive reduction of residual Doppler shift with increasing resolution. Our theoretical model of the atom–light interaction is in agreement with the observed effect and allows us to quantify its contribution in the uncertainty budget.

Micromaser cavity field spectrum by atomic beam measurements

It is shown that complete information on the micromaser cavity field correlation function and hence the spectrum for the cavity field at absolute zero is encoded on the atomic beam exiting from the cavity. A possible means of measuring the atomic beam correlation function is discussed.

Nuclearmoments and charge radii of bismuth isotopes

Isotope shifts and hyperfine structures have been measured on the306.7 nm line in bismuth isotopes with A = 205-210, 210m, 212 and213 by gas cell laser spectroscopy. More precise measurements were madefor the A = 207-209 isotopes in atomic beam measurements. Nuclearmagnetic and quadrupole moments were deduced. A detailed comparison ofthe nuclear charge radii systematics has been made in the region using aKing plot technique.

Direct measurement of the fine-structure interval of27Alin its ground2Pstate

The $J=\frac{3}{2}\ensuremath{\leftarrow}\frac{1}{2}$ fine-structure transition in atomic ${}^{27}\mathrm{Al}$ in its ground ${}^{2}P$ state has been detected in the laboratory by far-infrared laser magnetic resonance. The fine-structure interval has been measured accurately as 3359.6228(17) GHz or 112.064 95(6) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. The spectra show the hyperfine structure associated with a nuclear spin of $\frac{5}{2}$ for ${}^{27}\mathrm{Al}.$ The splittings are well reproduced by the hyperfine parameters determined earlier by atomic beam methods. The analysis of the laser magnetic-resonance spectra casts doubt on the published value for the Zeeman parameter ${g}_{3/2}$ also from the atomic beam measurements. Although the value determined in this paper is intrinsically much less accurate, it is in better agreement with the value obtained by a completely independent theoretical calculation.

Isotope shifts in ?326.1 nm of CdI

We have measured isotope shifts in λ326.1 nm of CdI using a pressure-scanned interferometer. The results are, in GHz: 116–106, −2.222 (30); 113–108, −1.052(10); 111–110, −0.049 (12); 111–106, −1.048 (10). Results for stable isotopes in λ326.1 nm are needed in the interpretation of existing measurements on radioactive cadmium isotopes. The new data are more precise than early atomic beam measurements but are reasonably consistent with them.

Atomic-beam measurement of parity nonconservation in cesium.

We present a new measurement of parity nonconservation in cesium. In this experiment, a laser excited the 6S\ensuremath{\rightarrow}7S transition in an atomic beam in a region of static electric and magnetic fields. The quantity measured was the component of the transition rate arising from the interference between the parity nonconserving amplitude, ${\mathrm{scrE}}_{\mathrm{PNC}}$, and the Stark amplitude, \ensuremath{\beta}E. Our results are Im${\mathrm{scrE}}_{\mathrm{PNC}/\mathrm{\ensuremath{\beta}}=\mathrm{\ensuremath{-}}1.65\ifmmode\pm\else\textpm\fi{}0.13}$ mV/cm and ${C}_{2p}$=-2\ifmmode\pm\else\textpm\fi{}2, where ${C}_{2p}$ is the proton-axial-vector--electron-vector neutral-current coupling constant. These results are in agreement with previous less precise measurements in cesium and with the predictions of the electroweak standard model. We give a detailed discussion of the experiment with particular emphasis on the treatment and elimination of systematic errors. This experimental technique will allow future measurements of significantly higher precision.

EPR of the vanadyl ion in Tutton salts at zero magnetic field

EPR measurements at zero magnetic field have provided accurate measurements of hyperfine principal values for the vanadyl ion doped in a series of Tutton salts. Unlike in previous EPR determinations, the in-plane anisotropy of the hyperfine tensor was found to vary only slightly from one environment to another. The nuclear quadrupole interaction term has also been determined from the zero-field spectrum and yields a value for the nuclear quadrupole moment of 51V in agreement with that determined from atomic-beam measurements.

Precision measurement of relative oscillator strengths for Ti I - I. Transitions from levels a3 F2 (0.00 eV) and a3 F3 (0.02 eV) and a3 F4 (0.05 eV) measured with an accuracy of 0.5 per cent

The paper presents measures of the relative oscillator strengths of 45 ground state lines of Ti I, for the range |$+0.215\,\gt\,\text{log}\,gf\,\gt\,- 3.84$|⁠, made with an accuracy of 0.5 per cent using the Oxford furnace technique. The relative measurements have been placed provisionally on an absolute scale using the atomic beam measurements of Bell et al. and the lifetimes measured by Roberts et al. This scale has an accuracy of about 12 per cent. Comparisons are made with the measured values of other experimenters and with the results of calculations.

Atomic beam measurement of the lifetime of the3 P 1 metastable states of Mg and Ca

The lifetime of the metastable level3P1 of Mg and Ca have been measured in an atomic beam experiment. We excite the atoms to the3P1 state by electron collisions and we measure the decay length of the light emitted by the beam. The velocity distribution of the atoms is also measured by a time-of-flight technique. The decay length and the velocity measurements are then combined to compute the required lifetimes. The results are (2.4±0.2)×10−3 sec for Mg and (0.55±0.04)×10−3 sec for Ca.

Determination ofgJ(He4, 2S13)gJ(H1, 1S122): Resolution of a Discrepancy

A new measurement of the ${g}_{J}$ factor in the $2^{3}S_{1}$ metastable state of $^{4}\mathrm{He}$ has been made using an optical-pumping technique. Our result is $\frac{{g}_{J}(^{4}\mathrm{He}, 2^{3}S_{1})}{{g}_{J}(^{1}\mathrm{H}, 1^{2}S_{\frac{1}{2}})}=1\ensuremath{-}23.15(10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. This value agrees with theory and provides confirmation of a recent atomic-beam measurement. Further doubt is cast on an earlier optical-pumping determination, thereby resolving a possible discrepancy between theory and experiment.

Atomic-beam measurements on refractory elements: Nuclear spin measurements of 99Mo and 99mTc

A technique has been developed for making atomic-beam magnetic-resonance experiments on refractory elements. The atomic beam is produced by heating a small ball at the end of a wire by means of electron bombardment. The technique is primarily intended for radioactive work, and it is sensitive enough for investigations on neutron-deficient nuclei. In this work the spin values of two radioactive isotopes are reported, namely 99Mo (67 h), I = 12, and 99mTc (6 h). I = 12, The measured spin values are compared with spectroscopic results and discussed in terms of the nuclear models.

MEASUREMENT OF PRlMARY ELECTRON INTERACTION COEFFICIENTS (500 TO 1500 eV REGION)

Because electrons of incident energy in the 500-1 500 eV range interact appreciably within only a few atomic layers in solids, precisely measuring and applying their interaction coefficients becomes difficult. The statistics of the interactions and the sensitivity to the geometric arrangement of the target atoms require special attention. A method for the study of such interactions is presented here that is based upon the controlled deposition of monatomic layers of bivalent metal cations as targets within the framework of stearate double layers of the LangmuirBlodgett type. To demonstrate the method, cross sections of the barium cation have been measured at 466 eV, 706 eV and 1 349 eV, and those of zinc and lead at 706 eV. The measured values are shown to be consistent with recent atomic beam measurements on barium and with simple theoretical models. Measurements of this type are considered to be of great importance in the development of quantitative surface chemical analysis by low energy X-ray and electron spectroscopy.

Mössbauer Effect in the 121.2-keV Transition inSm147

The M\"ossbauer effect has been observed in the decay of the ${\frac{5}{2}}^{\ensuremath{-}}$ 121.2-keV state of ${\mathrm{Sm}}^{147}$. Sources were ${\mathrm{Pm}}^{147}$ in a mixed Pm-Sm oxide matrix and ${\mathrm{Eu}}^{147}$ in ${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3}$. Both types of sources gave single Lorentzian lines when used with an ${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3}$ absorber. The ${\mathrm{Eu}}^{147}$ source was used with a samarium iron garnet absorber to obtain the excited-state nuclear moments. The magnetic dipole moment is found to be $\ensuremath{-}0.445\ifmmode\pm\else\textpm\fi{}0.025{\ensuremath{\mu}}_{N}$. Using an atomic-beam measurement of the ground-state quadrupole splitting, an estimate of -0.31 \ifmmode\pm\else\textpm\fi{} 0.12 b is obtained for the excited-state quadrupole moment. Three light rare-earth odd-neutron nuclei have now been studied by the M\"ossbauer effect: ${\mathrm{Nd}}^{145}$, ${\mathrm{Sm}}^{147}$, and ${\mathrm{Sm}}^{149}$. The $g$ factors for the low-lying levels of these nuclei cluster about -0.22. The present theoretical models are not particularly successful in accounting for the magnetic moments.

Calculation of Spin–Orbit Coupling Constants and Other Radial Parameters for the Actinide Ions Using Relativistic Wavefunctions

Relativistic self-consistent Dirac–Slater and Dirac–Fock wavefunctions have been used to evaluate the spin–orbit coupling constant and matrix elements of rn for most of the actinide ions and neutral atoms. Empirical corrections for the Dirac–Slater ζ5f constants based on experimental results are suggested which enable one to predict free-ion values more accurately. Values of ζ5f from crystal and solution spectra show reductions from these estimates which are independent of atomic number Z, but vary roughly according to ionic charge and ligand electronegativity. It is shown that 〈r−3〉 parameters from atomic beam measurements on Sm, Eu, Pu, and Am can be accounted for fairly well with relativistic Dirac–Slater wavefunctions and intermediate coupling eigenvectors; configuration interaction, core polarization, and other contributions to hyperfine coupling are neglected. Similar calculations with hyperfine coupling constants from crystal EPR spectra are less consistently satisfactory.

Calculation of the He–H Interaction Energy

The He–H interaction energy has been calculated by an SCF open-shell procedure due to Roothaan. Results obtained are in good agreement with the interaction deduced from atomic-beam measurements of Amdur and Mason. The present calculation has yielded lower values for the short-range potential than other comparable theoretical calculations.

Revised Absolute ƒ-VALUES for λ3247 of Neutral Copper and λ3720 of Neutral Iron

view Abstract Citations (34) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Revised Absolute ƒ-VALUES for λ3247 of Neutral Copper and λ3720 of Neutral Iron Bell, Graydon D. ; Tubbs, Eldred F. Abstract Recent atomic-beam measurements of absoluteJ-values for the resonance lines of neutral copper and iron yield values which are about 30 percent higher than atomic-beam values reported in the past. The new values are 0.43 for x3247 of Cu I and 0.041 for 3720 of Fe I. In the case of copper, the new value is in excellent agreement with recent measurements of lifetimes. In the case of iron, some discrepancies between results obtained by different investigations still exist. Nevertheless, the need for a 0.1-dex reduction in the Corliss and Tech absolute scale of log gJ-values for iron is indicated. Publication: The Astrophysical Journal Pub Date: March 1970 DOI: 10.1086/150388 Bibcode: 1970ApJ...159.1093B full text sources ADS |

Ionization and excitation of nitrogen by protons and hydrogen atoms in the energy range 1-25 keV

Abstract : Recent measurements of the energy spectra of protons and hydrogen atoms in breakup auroras have found significant fluxes at energies near 1 keV. Cross sections for ionization and light emission for collisions of protons and hydrogen atoms with atmospheric gases are useful in analysis of these auroral events. Atomic beam measurements are reported of ionization and charge-capture cross sections for proton bombardment N2, of ionization and stripping cross sections for hydrogen atom bombardment of N2, and of the relative cross sections for emission of N2(+) 391.4-nm radiation in collisions of protons and hydrogen atoms with N2 in the energy range 1-25 keV. (Author)

Lunar Experiments: The Moon as a Site for Certain Physical Measurements

If the lunar surface becomes available for conducting physical experiments, it may be particularly suited to thermal neutron and molecular and atomic beam measurements. The application of these beams for the purpose of communication on the lunar surface appears possible.

Low-Lying Energy Levels of Lanthanide Atoms and Intermediate Coupling

A detailed examination of the effects of intermediate coupling on the properties of the low-lying levels of lanthanide atoms has been made. Particular attention has been given to the effects of a breakdown of Russell-Saunders coupling on the energies and magnetic properties of the levels of the ground multiplets. The energy levels were calculated by diagonalization of the combined electrostatic and spin-orbit matrices of the ${f}^{n}$ configurations. It is found possible to fit the energy levels of the ground multiplets of Nd i and Sm i to within 2 ${\mathrm{cm}}^{\ensuremath{-}1}$ of their observed energies using $4f$-hydrogenic ratios for the Slater ${F}_{k}$ integrals. The $g$ values are found to agree within the experimental errors of the atomic beam measurements. An explanation for the apparent success of the $4f$-hydrogenic eigenfunctions is offered and it is demonstrated that the success of these eigenfunctions does not imply that the actual eigenfunctions are hydrogen-like. Tables of the calculated energies and eigenvectors for low-lying levels are given together with the $g$ values calculated in intermediate coupling. The effects of intermediate coupling on the realtivistic and diamagnetic corrections to the $g$ values are examined and shown to fall within the range of atomic beam measurements. The importance of intermediate coupling in the actinides is noted.

Hyperfine Interactions in Rare-Earth Metals

Estimates of the hyperfine interaction constants for the rare-earth metals are compiled from electron spin resonance and electron-nuclear double resonance data on salts, and atomic beam measurements on free atoms. Correction terms for second-order effects of the hyperfine structure are considered and shown generally to be small. Comparison with the experimental data (mostly from specific heat measurements below 1°K) shows close agreement in all cases except praseodymium, which is known not to have a co-operative phase. The temperature independent susceptibility of this metal below 4°K can be explained using a ferromagnetic exchange interaction of reasonable size, and the source of the observed hyperfine specific heat is discussed. In neodymium and samarium it is likely that crystal field effects are more important than exchange in determining the ground state in the co-operative phase.