A high stability semiconductor laser system for a 88^{88}Sr-based optical lattice clock

We describe a frequency stabilized diode laser at 698 nm used for high resolution spectroscopy of the 1S0-3P0 strontium clock transition. For the laser stabilization we use state-of-the-art symmetrically suspended optical cavities optimized for very low thermal noise at room temperature. Two-stage frequency stabilization to high finesse optical cavities results in measured laser frequency noise about a factor of three above the cavity thermal noise between 2 Hz and 11 Hz. With this system, we demonstrate high resolution remote spectroscopy on the 88Sr clock transition by transferring the laser output over a phase-noise-compensated 200 m-long fiber link between two separated laboratories. Our dedicated fiber link ensures a transfer of the optical carrier with frequency stability of 7 \cdot 10^{-18} after 100 s integration time, which could enable the observation of the strontium clock transition with an atomic Q of 10^{14}. Furthermore, with an eye towards the development of transportable optical clocks, we investigate how the complete laser system (laser+optics+cavity) can be influenced by environmental disturbances in terms of both short- and long-term frequency stability.Comment: 9 pages, 9 figures, submitted to Appl. Phys.

An organometallic tetranuclear complex of μ4-PO4: [{(Cp*Cr)2(μ-OMe)2} 2(μ4-PO4)]X (X - I, PF6)

10.1021/om048974dOrganometallics2471401-1403ORGN

Metallophilicity in annular Ru2M2 derivatives of (HMB)RuII(tpdt) versus (Bis)-η2-dithiolate bonding in Ru2M derivatives of Cp*RuIII(tpdt) (HMB = η6-C6Me6; Cp* = η5- C5Me5; M = CuI, Ag(I,II), Au (I,)

10.1021/om0491950Organometallics244539-551ORGN

Syntheses and x-ray crystal structures of di- and trinuclear trithiolate-thioether-bridged complexes of ruthenium. Electrochemistry of mixed-valence triruthenium complexes

10.1021/om034189+Organometallics233547-558ORGN

Exotic and indigenous viruses infect wild populations and captive collections of temperate terrestrial orchids (Diuris species) in Australia

Four species of Diuris temperate terrestrial orchids from wild and captive populations were tested for the presence of polyadenylated RNA viruses. The genomes of three exotic viruses were determined: two potyviruses, Bean yellow mosaic virus and Ornithogalum mosaic virus, and the polerovirus Turnip yellows virus. The genomes of five indigenous viruses were detected, including four novel species. They were the potyvirus Blue squill virus A, another potyvirus, two proposed capilloviruses, and a partitivirus. Partitivirus infection is of interest as this group of viruses is also associated with endophytic fungi (mycorrhizae) that are necessary for the germination, growth, development of many terrestrial orchids. Sequence divergence data indicate post-European, pre-European, and endemic origins for these viruses via inoculum from introduced and native plants. The implications of the findings of this study for orchid conservation, and particularly reintroduction programs where viruses may be spread inadvertently to wild populations from infected propagation sources, are discussed