Jens C. Zorn

Hyperfine Structure of Thallium Iodide and an Upper Limit for the Electric Hexadecapole Moment of the Iodine Nucleus

The hyperfine structure of thallium iodide has been studied in the J = 3 and J = 4 rotational states in an attempt to observe a nuclear electric hexadecapole effect. This study was carried out on a high‐resolution molecular‐beam electric resonance spectrometer at very weak electric and magnetic fields. The molecule is well described by the usual five hyperfine interaction constants which are (in kilohertz) 205Tl127I203Tl127IeqQ− 438 916.3 ± 0.5− 438 917.3 ± 1.0c13.05 ± 0.053.09 ± 0.1c234.65 ± 0.1534.36 ± 0.3c3− 2.48 ± 0.1− 2.59 ± 0.2c4− 6.67 ± 0.05− 6.57 ± 0.1. No evidence for a hexadecapole interaction constant as large as 500 Hz was found; this result is interpreted as setting an upper limit of ∼ 10−47 cm4 for the nuclear electric hexadecapole moment of 127I.

Hyperfine Structure of Thallium Chloride

The radio‐frequency spectra of TlCl at very weak electric and magnetic fields have been measured with a molecular beam electric resonance spectrometer. From these spectra the hyperfine interaction constants for the four isotopic species of the molecule were calculated. The constants for 205Tl35Cl in the J = 2, υ = 0 state are: eqQ = − 15793.32(50) kHz, cCl = 1.38(10) kHz, cTl = 76.35(10) kHz, c3 = − 0.13(10) kHz, c4 = − 1.54(10) kHz. A test was made for the polarization of the chlorine nucleus in the electric field of the molecule by comparing the ratio of the quadrupole interaction constants for 205Tl35Cl and 205Tl37Cl to the ratio of the quadrupole interaction constants for the free chlorine atoms. The agreement of the two ratios is within their uncertainties, thus providing no evidence for a polarization effect. In addition, the dependence of the spin–rotation and spin–spin interaction constants on isotope was found to show good agreement with theory.

Hyperfine Structure of Thallium Bromide

The hyperfine structure of the J = 2 and J = 3 rotational states of TlBr has been measured with a molecular‐beam electric resonance spectrometer. Hyperfine transition frequencies were measured under conditions of very weak electric and magnetic fields. The linewidth was 500 Hz. The hyperfine interaction constants have been determined for 205Tl79Br, 203Tl79Br, 205Tl81Br, and 203Tl81Br in the first five vibrational states for J = 2. In addition, the interaction constants for J = 3, υ = 0 were determined for Tl79Br and Tl81Br, but it was not possible to resolve the effect of the two thallium isotopes in the J = 3 state. The spectra measured are well described by a hyperfine Hamiltonian containing the bromine quadrupole interaction, the spin–rotation interactions of both the thallium and the bromine nuclei, and both the scalar and tensor parts of the spin–spin interaction between the nuclei. The dependence of the magnetic hfs constants on vibrational state and on isotopic composition shows good agreement with...

Molecular Beam Electric Resonance Spectroscopy

Publisher Summary Beam spectroscopy has provided much of what is known about the fine structure of atoms, the hyperfine structures and g values of atoms and molecules, and the values of nuclear spins and moments. This chapter summarizes what has been achieved with molecular beam electric resonance (MBER) spectroscopy. The operation of a molecular beam resonance spectrometer is shown. The field (say, A field) of the spectrometer selects molecules in the desired quantum state; the beam then goes to a region (say C field) in which transitions to other quantum states may be induced, and the beam subsequently passes through B field quantum state selector to a detector. In contrast to the mode of operation of the usual absorption spectrometer, it is the flux of molecules, rather than the intensity of radiation, which is monitored: those changes are looked for in the flux of molecules, which can be correlated with the frequency of the radiation in the C field.

Hyperfine Structure of Indium Fluoride

The radiofrequency spectrum of the indium fluoride molecule, 115In19F, has been measured with a high resolution molecular beam electric resonance spectrometer. We determined the hyperfine structure in the J=1 and the J=2 rotational states of several vibrational levels under conditions of very weak external electric and magnetic fields. The ∼700 MHz electric quadrupole interaction constant of the indium nucleus changes by 0.010(1) MHz between adjacent rotational states. We looked for, but did not find, an electric hexadecapole interaction of the indium nucleus; the upper limit for the (hexadecapole) interaction constant is 2 kHz.

Hyperfine Structure of Sodium Iodide

A molecular‐beam electric resonance spectrometer has been used to study radio‐frequency transitions between the hyperfine‐structure sublevels of the J = 1 state of 23Na127I. Transitions for the first four vibrational states have been observed in very weak electric field and near zero magnetic field. The intramolecular interaction constants obtained for the ground vibrational state are: (eqQ)sodium = − 4073.0(10) kHz; (eqQ)iodine = − 262 140.7(10) kHz; csodium = 0.74(8) kHz; ciodine = 0.28(4) kHz; c3 = 0.17(8) kHz, c4 = − 0 27(8) kHz. The numbers in parentheses are the uncertainties in units of the last quoted digit. Constants for the excited vibrational states have been determined with less precision because fewer transitions were observed.

Detection of Metastable Atoms and Molecules with Continuous Channel Electron Multipliers

Detection of metastable He, H, Ne, Ar, Kr, Xe and molecular nitrogen with continuous channel electron multipliers

Effect of recoil on the velocity distribution of metastable atoms produced by electron impact

Supported in part by the National Aeronautics and Space Administration.

Time-of-Flight Experiments in Molecular Motion and Electron-Atom Collision Kinematics.

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Time-of-flight measurements of metastable state lifetimes.

W. E. Lamb, jr. and R. C. Retherford. Phys. Rev. 79, 549 (1950).