Measurements of quadrupole interaction frequencies of long-lived isomers with the level mixing spectroscopy (LEMS) method

The level mixing spectroscopy (LEMS) method has proven to be a very useful method to determine the quadrupole interaction frequency of an isomer in a solid host. Especially in the difficult cases, e.g. when the isomeric lifetime is very long or its spin is very high, the method yields valuable information which is not accessible with other methods (such as TDPAD). Since the development of the method some years ago, many experiments have been performed on high spin isomers in the lead region. The static quadrupole moment of isomers with lifetimes ranging from 20 ns up to 13 ms andspins up to 65/2 have been determined in neutron deficient isotopes of Bi, At, Fr andRa.     

Heterodyne detection of synchrotron radiation

A time integral method for the study of resonant nuclear scattering of synchrotron radiation in the forward direction is presented. The method relies on the interference of radiation scattered by nuclei in two samples, one moving with respect to the other. The method, termed heterodyne detection of synchrotron radiation, gives the same information on hyperfine parameters as the well known differential method. The general formalism is developed for the case where the reference is a single line sample and the investigated sample has magnetic or quadrupole splitting. The first experiments are discussed. A comparison of time differential synchrotron radiation spectroscopy, heterodyne detection and Mössbauer spectroscopy is given.     

Billion‐Fold Enhancement in Sensitivity of Nuclear Magnetic Resonance Spectroscopy for Magnesium Ions in Solution

β‐nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β‐NMR has previously been successfully applied in the fields of nuclear and solid‐state physics. In this work, β‐NMR is applied, for the first time, to record an NMR spectrum for a species in solution. ³¹Mg β‐NMR spectra are measured for as few as 10⁷ magnesium ions in ionic liquid (EMIM‐Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β‐NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry.     

g-factor of the 9/2+ isomeric state in 65Ni from transfer reaction

We report a measurement of the g-factor of the I ^π = 9/2⁺, t _1/2 = 22ns isomer in ⁶⁵Ni. The state of interest was populated and spin-oriented using a single-neutron transfer on an enriched ⁶⁴Ni target. The value, which was obtained, g(9/2⁺,^65m Ni) = - 0.296(3) is well in agreement with the g-factors of the other 9/2⁺ states in the region and with large-basis shell model calculations. The known g-factor of the 9/2⁺ isomer in ⁶³Ni was used in order to verify the strength of the hyperfine field of Ni( Ni) at room temperature.     

An ion cooler-buncher for high-sensitivity collinear laser spectroscopy at ISOLDE

A gas-filled segmented linear Paul trap has been installed at the focal plane of the high-resolution separator (HRS) at CERN-ISOLDE. As well as providing beams with a reduced transverse emittance, this device is also able to accumulate the ions and release the sample in bunches with a well-defined time structure. This has recently permitted collinear laser spectroscopy with stable and radioactive bunched beams to be demonstrated at ISOLDE. Surface-ionized ^{39, 44, 46}K and ⁸⁵Rb beams were accelerated to 30keV, mass separated and injected into the trap for subsequent extraction and delivery to the laser setup. The ions were neutralized in a charge exchange cell and excited with a co-propagating laser. The small ion beam emittance allowed focussing in the ion-laser overlap region, which is essential to achieve the best experimental sensitivity. Fluorescent photons were detected by a photomultiplier tube as a frequency scan was taken. A gate (typically 7-12μs wide) was set on the photomultiplier signal to accept the fluorescent photons within the time window defined by the bunch. Thus, using accumulation times of 100ms, the dominant contribution to background due to continuous laser scattering could be reduced by a factor of up to 4×10⁴ .     

Pt10Ni10(111) single crystal alloy: Determination of the surface composition by AES,XPS and ISS

The surface composition of the Pt₁₀Ni₉₀(111) single crystal alloy has been determined from AES, XPS and ISS experiments. The clean surface is largely enriched with platinum: 30–40% in the top layer instead of 10% in the bulk. This enrichment concerns mainly the ultimate surface layer and appears to be only slightly dependent on the sample temperature.     

Nuclear level mixing resonances on non-axially symmetric systems

For several years, nuclear Level Mixing Resonances (LMR) have been well studied, both theoretically [1,2] and experimentally [3,4]. The experimental results show that LMR is a very powerful technique to determine the static quadrupole interaction frequencies of long living isomers (10 ns up to 100 ms). The LMR formalism has been developed for isomers implanted in a solid host, providing an axially symmetric electric field gradient (EFG). In this paper, the theory has been elaborated to non-axially symmetric systems (η≠0). It will be shown that these systems have some special features, for example the possibility to derive the asymmetry η of the EFG if its orientation (ß, γ) in the LAB system is known.