Investigation Of Hyperfine Structure Research Articles

Investigation of the Hyperfine Structure of Ta I lines (VII)

We have classified about 400 new spectral lines of neutral tantalum via laser excitation or observation of laser-induced fluorescence. 37 energy levels with even parity and seven levels with odd parity were found by means of systematic hyperfine structure investigations. For the new levels angular momentum, parity, magnetic hyperfine interaction constant A and electric quadrupole interaction constant B were deduced. In addition, we have classified 230 new lines observed in high resolution Fourier transform spectra by analysing their observed hyperfine structure patterns.

Hyperfine Structure Investigations of Mn I. Part I: Experimental and Theoretical Studies of the Hyperfine Structure in the Even Configurations

Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 12 spectral lines of Mn I in the wavelength regions of 660–645 nm and 933–911 nm. Experimental hyperfine structure constants A and B of the isotope 55Mn have been determined for seven levels of even and seven levels of odd parity. Additionally, a parametric analysis of the fine structure and the magnetic dipole hyperfine structure has been performed for the three even configurations 3d54s2, 3d64s and 3d7. Very large values for the ratio a3d10/a3d01 are found. Theoretical predictions for the magnetic dipole hyperfine structure constants A for all levels of the configurations 3d54s2, 3d64s and 3d7 are given.

Investigation of the quadrupole coupling hyperfine structure due to two nuclei by molecular beam Fourier transform microwave spectroscopy: spectra of dichlorofluoromethane and pyridazine

The nuclear quadrupole coupling hyperfine structure arising in the rotational spectra of dichlorofluoromethane and pyridazine due to the presence of two equivalent quadrupolar nuclei (Cl and N, respectively) has been investigated using molecular beam Fourier transform microwave spectroscopy in the 6–18 GHz frequency range. For dichlorofluoromethane the species CH 35Cl 2F, CH 35Cl 37ClF and CH 37Cl 2F have been investigated whereas for pyridazine only the parent species with two 14N has been observed. Thanks to the sub-Doppler resolution and high sensitivity inherent to this technique, the hyperfine structure for the low J transitions has been resolved and the complete nuclear quadrupole coupling tensors have been determined. Diagonalization of the tensor for dichlorofluoromethane molecule has given interesting information which reveals very small deviations between the Cl nuclei quadrupole coupling tensors principal axes z and the ClC bonds. The experimental results have been compared with those from MP4/6-311+G(2d,2p) ab initio calculations.

An injection seeded narrow bandwidth pulsed optical parametric oscillator and its application to the investigation of hyperfine structure in the PF radical

We describe the construction of an all solid-state, narrow bandwidth, pulsed optical parametric oscillator (OPO) based on β-barium borate nonlinear crystals. The OPO was injection seeded by an external cavity diode laser in the range 755–855 nm to generate high power narrow bandwidth tunable light in this range and simultaneously at 606–669 nm. The bandwidth of the visible light was ∼130 MHz, and after frequency doubling or sum frequency mixing with the second harmonic of the pump Nd:YAG laser, sub-Doppler spectra with an overall resolution of 450 MHz were taken in the UV. The system is demonstrated by taking high-resolution spectra of the v′=2–3 and 5–7 bands of the A 3Π–X 3Σ−(v′,0) progression and the v′=4–v″=0 band of the d 1Π–a 1Δ transition in PF. These spectra show clear hyperfine structure, and an analysis of this structure is presented and interpreted in terms of the electronic structure of the molecule. As a prelude to this high-resolution study, the first ten members of the A–X band system and the first five members of the d–a band system were recorded at the moderate resolution provided by a pulsed dye laser.

Application of the laser ion source for isotope shift and hyperfine structure investigation

The study of nuclei far from stability requires high sensitivity of the experimental technique. The method of Resonance Ionization Spectroscopy in a Laser Ion Source (RIS/LIS) allows one to carry out measurements of the isotope shifts and hyperfine splittings for isotopes at the production rate about 102 atoms per second. The sensitivity of this method is determined by the high efficiency of the laser ion source and the low background of the detection system afforded by characteristic α particle registration. The isotope shifts and hyperfine structures of 155Yb, 154Tm (I=9 and I=2) and 153Tm (I=11/2) have been measured and the isotopic changes in mean square charge radii and nuclear electromagnetic moments have been determined. The further development of this experimental method – enhanced Target Ion Source system aimed to suppress thermionic background – enables direct detection of the photoions and widens the range of the applicability of the RIS/LIS method.

Study of the hyperfine structure of Titanium atom by laser induced fluorescence on an atomic beam

Within the framework of systematic hyperfine structure (hfs) investigation of titanium atom the hfs splitting of 3d34s3H4,5,6 levels for two stable isotopes 47Ti and 49Ti have been measured by laser induced fluorescence. Experimental hfs constants Aexp and Bexp have been determined. The hfs measurements confirm an existence of a significant spin-dependent interaction effect on hfs structure of the level 3d3 4s3H4.

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.

Pulsed EPR investigation of hyperfine structure in γ-irradiated alanine

Pulsed EPR investigation of hyperfine structure in γ-irradiated alanine

Hyperfine structure investigations and identification of new energy levels in the ionic spectrum of 147Pm

Hyperfine structure splittings have been measured for 75 lines of singly ionized promethium 147Pm II with a hollow cathode discharge and a Fabry-Perot interferometer. Magnetic dipole and electric quadrupole splitting factors A and B have been determined for 10 levels of the 4f56s configuration, 2 levels of 4f55d, and 57 upper undesignated levels. The A-factors are in general agreement with calculated values. With the aid of Hartree-Fock calculations and Zeeman-effect data, four new levels of the 4f5(6H)5d 7K term were located. The strong lines terminating on these 7K levels originate from levels of 4f5(6H)6p7I, which were already known, but had not been designated. An unidentified line at 556.17 nm previously observed with collinear laser ion-beam spectroscopy is now classified as 4f5(6H)5d7K6-4f5(6H)6P7I5.

Hyperfine structure and isotope-shift investigations of atomic nitrogen by saturation spectroscopy.

In this work we report a Doppler-free investigation of atomic nitrogen. As a laser source we used a narrow-band semiconductor diode laser emitting in the near infrared. Atomic nitrogen was produced by dissociating ${\mathrm{N}}_{2}$ molecules in a radio-frequency discharge sustained by helium as a buffer gas. Hyperfine structures and isotope shifts of the transitions 3p $^{4}$${\mathit{P}}_{1/2\mathrm{\ensuremath{-}}5/2}$--3s $^{4}$${\mathit{P}}_{1/2\mathrm{\ensuremath{-}}5/2}^{\mathit{o}}$ were investigated for the two stable isotopes $^{14}\mathrm{N}$ and $^{15}\mathrm{N}$ by using absorption-saturated laser spectroscopy.

Upper limits of higher nuclear moments of47Ti and49Ti

Within the framework of systematic hyperfine structure (hfs) investigation of titanium atom the hfs-splittings of 3d3(2G)4s b1G4 levels for two stable isotopes47Ti and49Ti have been studied. 5 hfs intervals for each isotope have been measured using ABMR-LIRF method (atomic beam magnetic resonance detected by laser induced resonance fluorescence) with an accuracy of about 300 Hz. TheJ-off-diagonal second order perturbation effects have been taken into account in the interpretation. Upper limit of the contributions from octupole and hexadecapole hyperfine structure interaction to hfs intervals of this level have been estimated to be about 400 Hz. However, for most of hfs intervals these contributions are almost within experimental error and in order to study such effects a more precise experimental method should be used.

Hyperfine structure investigation on the (3d 4)3 G 4,5 levels of47Ti

Using two-step laser spectroscopy with the sideband technique the hyperfine structure (hfs) splittings of the levels (3d4)3G4,5 in47Ti have been measured. These are the first hfs measurements of the levels belonging to the 3dN+2 configuration of the system (3d+4s)N+2. The experimental results indicate a strong increase of the core polarization effect due to excitation of both 4s-electrons to the open 3d-shell.

Hyperfine structure investigations of the tantalumI blend ?=6356.14 �

The TaI line 6356.14 A, up to now classified as the transition 5d36s2a4P5/2−5d36s(a5F)6p z4F72/0, is a blend with a second transition, which is related to the additional levels 5d4(b3G)6s a4G9/2−39641.24 cm−1J=7/2°. Using laser excitation with optogalvanic and laser-induced fluorescence detection, the hyperfine constants of the four levels involved and the distance of the center wavelengths of the two fine structure transitions could be determined.

Hyperfine structure investigations of the excited AO+state of TlI

Hyperfine splittings in several bands of the A-X system of TlI were measured using laser excitation spectroscopy on a highly collimated molecular beam. The quadrupole coupling constant in the A state and its dependence on the vibrational quantum number ν′ was derived. The results are discussed in a simple model with the assumption of an avoided crossing.

Optical laser spectroscopy and hyperfine structure investigation of the 102S, 112S, 82D, and 92D excited levels in francium

The authors present an extension to low-lying states of francium (10s, 11s, 8d, 9d) of a previously published high-resolution experiment performed on the ns and nd Rydberg levels. These four levels were investigated at CERN with the on-line mass separator ISOLDE using stepwise laser excitation in collinear geometry. Accurate energy measurements lead to a more reliable determination of the quantum defects of the whole ns and nd series, together with the ionization potential for 212Fr (nuclear spin I=5) which is found to be 32848.872 (9) cm-1. The measurement of the fine structure splittings for the nd 2D3/2, 5/2 doublets was completed at the same time. The main result of the study is the first observation and measurement of hyperfine structures in 2S and 2D states.

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.

11B-Quadrupole Hyperfine Structure in the Rotational Spectrum of Phenyldifluoroborane

Abstract We present an investigation and interpretation of the 11B-quadrupole hyperfine structure (hfs) in the rotational spectrum of phenyldifluoroborane in the torsional ground state of the BF2 group. The measurements were made with a microwave Fourier transform (MWFT) spectrometer in the frequency range between 5 and 8 GHz.

Hyperfine-structure investigations in the Co I spectrum

Using Doppler-limited optogalvanic spectroscopy in a DC hollow-cathode discharge the authors were able to reveal the blend of the Co I lambda =645.023 nm line. It turned out to be a near coincidence between the transitions 3d74s2 a 4P5/2-3d74s(a 5P)4p z 4Do7/2 and 3d74s2 a2G7/2-3d74s(b 3F)4p z 2Go7/2, the latter lying on the blue side of the spectrum. The hyperfine-structure constants of the levels involved were determined to be: a 4P52/: A=182 (2) MHz B=-237 (20) MHza 2G7/2: A=855 (9) MHzB=-130 (80) MHz z 4Do7/2: A=755 (2) MHzB=-67 (30) MHz z 2Go7/2: A=927 (2) MHzB=244 (60) MHz. Measuring laser-induced fluorescence modulation of independent decay channels of the respective upper levels enables them to calculate the frequency difference Delta v between the centres of gravity of the two lines Delta v=12067 (60) MHz and the integrated intensity ratio I(a 4P5/2-z 4Do7/2)/I(a 2G7/2-z 2Go7/2)=2.7 (2).

Quadrupole Hyperfine Structure in the Rotational Spectrum of n-PropylIsocyanide

An investigation of the 14N quadrupole hyperfine structure in the rotational spectrum of n-propyl isocyanide is presented. It was possible to resolve the multiplets by using microwave Fourier transform spectroscopy.

Hyperfine structure and isotope shift investigations in202–222Rn for the study of nuclear structure beyond Z=82

The hyperfine structure (hfs) and isotope shift (IS) in the isotopic chain of the radioactive element radon have been studied for the first time. The measurements were carried out by collinear fast-beam laser spectroscopy at the mass separator facility ISOLDE at CERN. The IS between 16 isotopes in the mass range 202≦A≦222 and the hfs of 7 odd-A isotopes were determined in the transitions 7s [3/2]2-7p [5/2]3 (745 nm) of Rn I. The nuclear spins and moments, as well as the observed inversion of the odd-even staggering for218–222Rn, can be associated with the effects of octupole instability around N=134.