Ultraviolet spectroscopy of 233 U and 232 U, in the form of uranium oxide dissolved in 3M nitric acid, has revealed a number of spectral lines with widths of less than 6 nm from the 233 U source but no detectable narrow lines from the 232 U source. These lines could possibly be attributed to the decay of the 229 Th isomeric state at an energy of around 4.0 eV. [S0031-9007(98) PACS numbers: 23.20.Lv, 27.90. + b, 32.30.Jc In 1994 Helmer and Reich [1] determined the separation of the ground and first excited nuclear states in 229 Th to be 3.5 61.0 eV. Recently the direct decay from this state may have been observed at higher resolution [2]. This is then the lowest excitation energy for a nuclear first excited state yet found and the first to be on a similar energy scale to atomic valence electrons. Such a small energy separation provides the potential to examine a regime of nucleus-atom interactions not previously observable. The value for the excitation energy was obtained by applying the Ritz combination principle to groups of g-ray energies of several tens to hundreds of keV. Using energies of 4-5 orders of magnitude larger than the energy under investigation makes it difficult to increase the accuracy of the measured energy separation by this method.The spins and parities of the ground and first excited states together with the small excitation energy suggest that the excited state should be a long lived isomeric state [3]. A photon emitted by the direct decay of the first excited state to the ground state would have a wavelength in the blue-ultraviolet region of the electromagnetic spectrum, i.e., between 270 and 500 nm, with 3.5 eV corresponding to 350 nm. Thus conventional UV spectroscopy is an ideal tool for increasing the accuracy to which the separation is known. A recent experiment [2] used UV spectroscopy of two solid sources of 233 U to look for the 229 Th-isomer deexcitation following the a decay of the 233 U. The results show a broad spectral feature at ϳ2.5 eV, with a set of spectral lines centered at approximately 3.5 eV.In the current work a 233 U source was also used; however, the radioactive isotope was in the form of uranium oxide dissolved in 3M nitric acid, producing an equilibrium in which uranyl nitrate ions dominate (UO 2 NO 1 3 ). The source activity was 4 MBq and its volume of 0.25 ml was contained in a 6 mm internal diameter quartz tube. 233 U has an a-decay half-life of 1.7 3 10 5 years, which ensures the activity will be essentially constant throughout the course of the experiment. It has been estimated that about (1-2)% of the total a decays of the uranium feed into the 229 Th first excited state [4,5]. Because both 233 U and 229 Th have long half-lives it was not considered necessary to remove the daughters produced since the production of the 233 U source in 1992.A control source, with 232 U as the main active element, was also made. The half life of 232 U is 72 yr, which, while adequate for the duration of the measurements means that a substantially smaller quantity of the isot...

The first fully on-line isotope shift measurement of a radioactive refractory element is reported. Collinear laser-induced fluorescence measurements were made on the radioactive isotopes 170,172,173,174 Hf produced with a flux of 2 3 3 10 3 ions per second from an ion-guide fed isotope separator. The method may be applied to all elements and isomers with lifetimes as short as 1 ms. The systematics of the new charge radii measurements are well reproduced by theory, with the maximum deformation in the chain occurring significantly below the midshell. [S0031-9007(99)

Nanofabrication through conventional methods such as electron beam writing and photolithography is time-consuming, high cost, complex, and limited in terms of the materials which can be processed. Here, we present the development of a nanosecond Nd:YAG laser (532 nm, 220 mJ) in holographic Denisyuk reflection mode method for creating ablative nanopatterns from thin films of four ink colors (black, red, blue, and brown). We establish the use of ink as a recording medium in different colors and absorption ranges to rapidly produce optical nanostructures in 1D geometries. The gratings produced with four different types of ink had the same periodicity (840 nm); however, they produce distant wavelength dependent diffraction responses to monochromatic and broadband light. The nanostructures of gratings consisting of blue and red inks displayed high diffraction efficiency of certain wavelengths while the black and brown ink based gratings diffracted broadband light. These gratings have high potential to be used as low-cost photonic structures in wavelength-dependent optical filters. We anticipate that the rapid production of gratings based on different ink formulations can enable optics applications such as holographic displays in data storage, light trapping, security systems, and sensors.

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