Bulletin of the American Physical Society.

Chemical abstractsMode of access: Internet.Issues for have separately titled section: APS news, which beginning in 1992 is published as a separate periodical.Directory of physics & astronomy staff, supplied as part 2 of the Dec. issue, 1986-1991.Issue for -Dec. 1989 is the Society's Membership directory (entitled, Dec. 1991, APS membership directory) issued biennially, Also issued online. Beginning in 2007, only issued online.Library has index to ser. 2, vol. 26 (1981

Transition from Coulomb Diamonds to Checkerboard-like Spectroscopies in a Mesoscopic Quantum Hall Interferometer.

We report low temperature ( 100 mK) magnetotransport, scanning gate microscopy and scanning gate spectroscopy measurements in an In0:7Ga0:3As=In0:52Al0:48As quantum point contact (QPC). The magnetoresistance of the QPC shows oscillations in the vicinity of in- teger quantum Hall states. We attribute these magnetoresistance oscillations to the formation of an electron interferometer around a small, disorder-induced quantum Hall island located within the constriction. The magnetic eld B tunes the edge states conguration in the QPC, leading to dierent signatures in the transport measurements. Interestingly, near the Landau level lling factor = 3, the spectroscopy measurements performed on the quantum Hall interferometer, as a function of B or scanning gate tip voltage, exhibit a smooth transition from Coulomb diamonds to a checkerboard pattern

Geoengineering, marine microalgae, and climate stabilization in the 21st century

Society has set ambitious targets for stabilizing mean global temperature. To attain these targets, it will have to reduce CO2 emissions to near zero by mid-century and subsequently remove CO2 from the atmosphere during the latter half of the century. There is a recognized need to develop technologies for CO2 removal; however, attempts to develop direct air-capture systems have faced both energetic and financial constraints. Recently, BioEnergy with Carbon Capture and Storage (BECCS) has emerged as a leading candidate for removing CO2 from the atmosphere. However, BECCS can have negative consequences on land, nutrient, and water use as well as biodiversity and food production. Here, we describe an alternative approach based on the large-scale industrial production of marine microalgae. When cultivated with proper attention to power, carbon, and nutrient sources, microalgae can be processed to produce a variety of biopetroleum products, including carbon-neutral biofuels for the transportation sector and long-lived, potentially carbon-negative construction materials for the built environment. In addition to these direct roles in mitigating and potentially reversing the effects of fossil CO2 emissions, microalgae can also play an important indirect role. As microalgae exhibit much higher primary production rates than terrestrial plants, they require much less land area to produce an equivalent amount of bioenergy and/or food. On a global scale, the avoided emissions resulting from displacement of conventional agriculture may exceed the benefits of microalgae biofuels in achieving the climate stabilization goals

Scanning Tunneling Spectroscopy of Organic Zwitterions Assembled on Si(111)-7x7.

We report on the molecular assembly and local electronic properties of organic zwitterions deposited on the Si(111)-7x7 surface. We analyze these molecular systems by scanning tunneling microscopy and spectroscopy down to low temperatures. The molecules adsorb at specific sites on the Si(111)-7x7 surface, forming star-shaped configurations composed of three zwitterions filling up a half unit cell [1]. The regioselectivity of the process is determined by electrostatic interactions between the substrate and the ionic species, resulting in mirrored configurations in neighboring half unit cells. Thus, we probe chiral assemblies of achiral molecules on Si(111)-7x7 by spatially-resolved tunneling spectroscopy. For all investigated systems, ab initio simulations of the relaxed structures and local density of states are compared to experimental data

Graphene growth by CVD using liquid precursors

Chemical vapor deposition (CVD) represents an attractive route to synthesize large-area graphene. Its catalytic growth using metals has been studied in recent years, the most popular being nickel and copper. We have successfully grown graphene on copper by CVD at ambient pressure using alcohols as the carbon feedstock. The produced materials are analyzed by SEM, TEM, Raman spectroscopy and transferred onto Si/SiO2 substrates using standard methods. Raman fingerprint of monolayer graphene is present in our samples. This technique represents a safer and more versatile alternative to the production of graphene compared to the synthesis of graphene using methane at low pressure

Isotope-Resolved and Charge-Sensitive Force Imaging Using Scanned Single Molecules

Originally conceived as surface imaging instruments, the scanning tunnelling microscope (STM) and the atomic force microscope (AFM) were recently used to probe molecular chemical bonds with exquisite sensitivity. Remarkably, molecule-functionalized scanning tips can also provide direct access to the inelastic electron tunneling spectrum (IETS) of the terminal molecule. Here we report atomic manipulation experiments addressing carbon monoxide (CO) isotopes at low temperatures. The unique and quantifiable dependence of the CO vibrational modes offers insight into tip-controlled force and charge sensing of surface adsorbates, subsurface defects, and quantum nanostructures. The specific behavior of the monitored vibrational modes originates from the interplay of interaction forces between the top electrode—a scanned tip functionalized with a single molecule—and the atomic scale force field surrounding the target atomically assembled nanostructure. We also present density functional theory (DFT) computations that have been performed in order to scrutinize and visualize the vibrational spectroscopic fingerprints and local force fields. Ya