Preparative isolation of (+)-beta-eudesmol fromAmyris balsamifera

Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum distillation of the total oil. Step two was a medium pressure LC separation with an AgNO₃ impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related sesquiterpene alcohols (75% of the oil).     

Isotonic and isobaric dependencies of nuclear charge radii for rare-earth nuclei

Isotonic and isobaric dependencies of nuclear charge radii in the region between Z=54 and Z=70 are obtained from the analysis of isotope shift data r² and muonic and electron scattering data on r². They are compared with the predictions of the droplet model and the Hartree-Fock calculations. The isobaric dependencies of r² have proven to be especially sensitive to the choice of an effective nucleon-nucleon interaction.     

Laser photoionization spectroscopy of rare-earth elements: New results on nuclear electromagnetic moments and charge radii of Eu,Gd and Tb isotopes

New results on spins, electromagnetic moments and isotopic changes of nuclear charge radii for ₆₃ ^157–159 Eu, ₆₄ ^{146, 148, 150} Cd and ₆₅ ^{147–155, 157, 159} Tb have been obtained from hyperfine structure and isotope shifte measured with laser resonance photoionization technique. These results complement two-dimensional picture (with respect to H and Z) of the changes of nuclear ground state properties near the “critical” neutron numbers N=88–90 in the vicinity of the “magric” proten number Z=64.     

Electromagnetic moments and nuclear charge radii for neutron-deficient Tb isotopes and the deformation jump nearZ=64,N=90

Optical isotope shifts and hyperfine structures of the^{147–153,155,157,159} Tb isotopes have been measured by the resonance ionization spectroscopy method. Nuclear moments and changes in nuclear charge radiiΔ 〈r ²〉 have been deduced. The “jump” inΔ 〈r ²〉 atN=88–90 has been revealed. It is compared with the relevant data for nuclei with other proton numbers.     

Isotope shift and hyperfine structure measurements for 155Yb by laser ion source technique

The change in the mean square charge radius and electromagnetic moments of the neutron deficient ¹⁵⁵Yb isotope have been determined using resonance ionization spectroscopy in a laser ion source. The data point to an absence of a marked deformation change for Yb isotopes with N=84−86. Received: 2 October 1997 / Revised version: 24 October 1997     

Atomic lines isotope shifts of short-lived radioactive Eu studied by high-sensitive laser resonance photoionization method in “on-line” experiments with proton beams

In “on-line” experiments the isotope shifts (IS) of ^141–144Eu have been measured at the mass-separator output. The overall detection efficiency of Eu atoms is equal to 3 x 10^-4. The accuracy of IS measurement is ±70 MHz and determined by laser linewidth.     

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. This revised version was published online in August 2006 with corrections to the Cover Date.     

Target-ion source unit ionization efficiency measurement by a method of stable ion beam implantation

At the IRIS facility a rather precise method of the target-ion source unit ionization efficiency measurement has been developed. The method exploits an off-line mass-separator for the implantation of the ion beams of selected stable isotopes into a tantalum foil placed inside a Faraday cup in the focal plane of the mass-separator. After the implantation of the required amount of the investigated species, tantalum foil has been inserted into the volume of the target-ion source unit prepared for the on-line utilization at the IRIS on-line separator. The first tests have ensured the ionization efficiency values (90±10)% for Rb and (85±10)% for Cs in the empty combined target-ion source unit, which was used as a reference one. For the target-ion source unit with UC target material inside the measured value of the ionization efficiency of Rb was (52±20)%.