We report 25,563 radial velocity measurements for 1359 single-lined stars in the Carney-Latham sample of 1464 stars selected for high proper motion. For 171 of these, we present spectroscopic orbital solutions. We find no obvious difference between the binary characteristics in the halo and the disk populations. The observed frequency is the same, and the period distributions are consistent with the hypothesis that the two sets of binaries were drawn from the same parent population. This suggests that metallicity in general, and radiative opacities in particular, have little influence over the fragmentation process that leads to short-period binaries. All the binaries with periods shorter than 10 days have nearly circular orbits, while the binaries with periods longer than 20 days exhibit a wide range of eccentricities and a median value of 0.37. For the metalpoor high-velocity halo binaries in our sample, the transition from circular to eccentric orbits appears to occur at about 20 days, supporting the conclusion that tidal circularization on the main sequence is important for the oldest binaries in the Galaxy.

The performance of bulk heterojunction organic photovoltaic devices is critically dependent on the morphology of the active layer. Here we describe the combination of two electron microscopy techniques to quantitatively examine the molecular level structure and mesoscopic domain morphology of the active layer of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester P3HT:PCBM bulk heterojunction solar cells. Energy-filtered transmission electron microscopy (EFTEM) revealed the nanoscopic, interpenetrating fibrillar structure of the phase separated blend, providing unique assignments of the P3HT-rich and PCBM-rich regions. Low-dose high-resolution electron microscopy (LD-HREM) provided direct images of the P3HT crystals and their orientation within the P3HT-rich domains. The high mobility [010] crystallographic direction of these crystals coincides with the P3HT fibril axis. Additionally, the width of the P3HT crystallite coincides with the width of the P3HT-rich fibril, and is less than that of P3HT crystals in comparably processed pure P3HT films. The local crystallite structure within the blend is commensurate with the constraints of the nanoscale interpenetrating morphology and confirms the intimate relationship between processing protocols, which define the mesoscale phase-separated domains, and the molecular level ordering within the domains, which determines local transport characteristics.

Device function in organic electronics is critically governed by the transport of charge across interfaces of dissimilar materials. Accurate measurements of energy level positions in organic electronic devices are therefore necessary for assessing the viability of new materials and optimizing device performance. In contrast to established methods that are used in solution or vacuum environments, here we combine Kelvin probe measurements performed in ambient environments to obtain work function values with photoelectron spectroscopy in air to obtain ionization potential, so that a complete energy level diagram for organic semiconductors can be determined. We apply this new approach to study commonly used electron donor and acceptor materials in organic photovoltaics (OPV), including poly(3-hexylthiophene) (P3HT), [6,6]-phenyl C61 butyric acid methyl ester (PCBM), and ZnO, as well as examine new materials. Band alignments across the entire OPV devices are constructed and compared with actual device performance. The ability to determine interfacial electronic properties in the devices enables us to answer the outstanding question: why previous attempts to make OPV devices using 6,13-bis(triisopropylsilylethynyl) (TIPS)-pentacene as the electron donor were not successful.

With the advent of all‐sky Hα surveys it is possible to determine a reliable free–free template of the diffuse interstellar medium which can be used in conjunction with the synchrotron and dust templates to correct cosmic microwave background (CMB) observations for diffuse Galactic foregrounds. We have used the COBE‐DMR data at 31.5, 53 and 90 GHz and employed cross‐correlation techniques to re‐evaluate the foreground contributions, particularly that due to dust which is known to be partially correlated with Hα (and free–free) emission. The DMR microwave maps are found to contain, as well as the expected synchrotron and free–free components, a component tightly correlated to the COBE‐DIRBE 140‐μm dust map. At 31.5, 53 and 90 GHz this emission is 6.3 ± 0.6, 2.4 ± 0.4 and 2.2 ± 0.4 μK MJy−1 sr at 140 μm, respectively. When corrected for the contribution from thermal dust, a strong anomalous dust‐correlated emission component remains, which is well fitted by a frequency spectrum of the form ν−β where β∼ 2.5 in the DMR frequency range; this is the dominant foreground at 31.5 GHz. The result implies the presence of an emission component with a dust‐like morphology but a synchrotron‐like spectrum. We discuss the possible origins of this component and compare it with the recent WMAP interpretation. The better knowledge of the individual foregrounds provided by the present study enables a larger area of the sky (|b| > 15°) to be used to reappraise the CMB quadrupole normalization, Qrms‐PS, and the scalar perturbations spectral index, n. We find Qrms‐PS= 15.2+2.8−2.3 with a power‐law spectral index of n= 1.2 ± 0.2. These values are consistent with previous COBE‐DMR analyses and the WMAP 1‐yr analysis.