Dissociation energy of the hydrogen molecule at 10−9^{-9} accuracy

The ionization energy of ortho-H$_2$ has been determined to be $E^\mathrm{o}_\mathrm{I}(\mathrm{H}_2)/(hc)=124\,357.238\,062(25)$ cm$^{-1}$ from measurements of the GK(1,1)--X(0,1) interval by Doppler-free two-photon spectroscopy using a narrow band 179-nm laser source and the ionization energy of the GK(1,1) state by continuous-wave near-infrared laser spectroscopy. $E^\mathrm{o}_\mathrm{I}$(H$_2$) was used to derive the dissociation energy of H$_2$, $D^{N=1}_{0}$(H$_2$), at $35\,999.582\,894(25)$ cm$^{-1}$ with a precision that is more than one order of magnitude better than all previous results. The new result challenges calculations of this quantity and represents a benchmark value for future relativistic and QED calculations of molecular energies.Comment: 6 pages, 5 figure

Benchmarking theory with an improved measurement of the ionization and dissociation energies of H2_2

The dissociation energy of H$_2$ represents a benchmark quantity to test the accuracy of first-principles calculations. We present a new measurement of the energy interval between the EF $^1\Sigma_g^+(v=0,N=1)$ state and the 54p1$_1$ Rydberg state of H$_2$. When combined with previously determined intervals, this new measurement leads to an improved value of the dissociation energy $D_0^{N=1}$ of ortho-H$_2$ that has, for the first time, reached a level of uncertainty that is three times smaller than the contribution of about 1 MHz resulting from the finite size of the proton. The new result of 35999.582834(11) cm$^{-1}$ is in remarkable agreement with the theoretical result of 35999.582820(26) cm$^{-1}$ obtained in calculations including high-order relativistic and quantum electrodynamics corrections, as reported in the companion article (M. Puchalski, J. Komasa, P. Czachorowski and K. Pachucki, submitted). This agreement resolves a recent discrepancy between experiment and theory that had hindered a possible use of the dissociation energy of H$_2$ in the context of the current controversy on the charge radius of the proton

IRIS: Efficient Visualization, Data Analysis and Experiment Management for Wireless Sensor Networks

The design of ubiquitous computing environments is challenging, mainly due to the unforeseeable impact of real-world environments on the system performance. A crucial step to validate the behavior of these systems is to perform in-field experiments under various conditions. We introduce IRIS, an experiment management and data processing tool allowing the definition of arbitrary complex data analysis applications. While focusing on Wireless Sensor Networks, IRIS supports the seamless integration of heterogeneous data gathering technologies. The resulting flexibility and extensibility enable the definition of various services, from experiment management and performance evaluation to user-specific applications and visualization. IRIS demonstrated its effectiveness in three real-life use cases, offering a valuable support for in-field experimentation and development of customized applications for interfacing the end user with the system

Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (Ni-MWNTs) with an average diameter of 115 nm and variable length of 400 nm-1μm. The Ni-MWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H2/C2H2 at a temperature of 700º C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive x-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess a fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template-based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNT

Large-Scale Selective Sweep among Segregation Distorter Chromosomes in African Populations of Drosophila melanogaster

Segregation Distorter (SD) is a selfish, coadapted gene complex on chromosome 2 of Drosophila melanogaster that strongly distorts Mendelian transmission; heterozygous SD/SD+ males sire almost exclusively SD-bearing progeny. Fifty years of genetic, molecular, and theory work have made SD one of the best-characterized meiotic drive systems, but surprisingly the details of its evolutionary origins and population dynamics remain unclear. Earlier analyses suggested that the SD system arose recently in the Mediterranean basin and then spread to a low, stable equilibrium frequency (1–5%) in most natural populations worldwide. In this report, we show, first, that SD chromosomes occur in populations in sub-Saharan Africa, the ancestral range of D. melanogaster, at a similarly low frequency (∼2%), providing evidence for the robustness of its equilibrium frequency but raising doubts about the Mediterranean-origins hypothesis. Second, our genetic analyses reveal two kinds of SD chromosomes in Africa: inversion-free SD chromosomes with little or no transmission advantage; and an African-endemic inversion-bearing SD chromosome, SD-Mal, with a perfect transmission advantage. Third, our population genetic analyses show that SD-Mal chromosomes swept across the African continent very recently, causing linkage disequilibrium and an absence of variability over 39% of the length of the second chromosome. Thus, despite a seemingly stable equilibrium frequency, SD chromosomes continue to evolve, to compete with one another, or evade suppressors in the genome

MQDT AND THE DOUBLE MINIMUM STATES OF H2H_{2}: BORN-OPPENHEIMER DOES NOT WORK HERE!

Author Institution: Department of Physics, University of New Brunswick; Laboratoire Aim\'e Cotton du CNRS, Universit\'eA de Paris–SudThe rovibronic structure of the double minimum states of $H_{2}$ exhibits the effects of strong interactions. these interactions couple rotational, vibrational, and electronic motion, and are of such a magnitude that the Born-Oppenheimer picture is not even approximately correct. In fact predictions, for vibronic energies based on the straightforward solution of the one dimensional Schrodinger equation on the Born-Oppenheimer potential energy curves disagree with experiment by hundreds of wavenumber units. Two theoretical approaches hove been used to study the rovibronic structure of the fundamental system. Dressler and co-workers have calculated with adiabatic corrections to the Born-Oppenheimer potential energy curves and the non-adiabatic interaction functions between the lower $^{1}\Sigma_{6}$ Rydberg states. These results they than combine into a coupled equations treatment of the rovibronic structure of the related state. The results they obtain using this ``traditional” approach reproduce the experimental novibronic energies of the lower Rydberg states to within several $cm^{-1}$. Our approach has been to study the same states using scattering theory. Multichannel Quantum Defect Theory (MQDT) is a version of scattering theory ideally suited to the study of such systems. In MQDT the concept of individual states is replaced by that of ``channels”. A channel consists of an entire Rydberg series and the continuum lying above it. By carefully determining the channels and their interactions a simple picture of a small number of interacting channels is thus sufficient to describe the entire {infinite} set of interacting states. MQDT thus avoid having to consider this infinity of mutually interacting states individually while still accounting for the effects of their interaction. In this talk the basis ideas of MQDT will be explained, with particular reference to our work on the double minimum states of $H_{2}$. the rovibronic energies we obtain are of similar quality to those of Dressler and co-workers from the more traditional technique. We plan to extend our technique to progressively higher states and eventually into the continuum, which will allow us to provide a single unified treatment of both bound an continuum states, including the possibility of determining cross sections for such processes as dissociative recombination and photoionization

ab initio R-matrix and MQDT investigation of low-lying Rydberg states of the HeH+ molecular ion

We report R-matrix calculations of low-lying Rydberg states of the hydrohelium molecular ion HeH+ corresponding to 1Δ and 3Δ symmetry. The calculations include states with principal quantum numbers 3 ≤ n ≤ 10. For n = 3 and n = 4 the present results are compared with those of Green et al. [1,2] and Loreau et al. [3]

R-matrix and MQDT investigation of low-lying Rydberg states of the HeH

We report R-matrix calculations of low-lying Rydberg states of the hydrohelium molecular ion HeH+ corresponding to 1Δ and 3Δ symmetry. The calculations include states with principal quantum numbers 3 ≤ n ≤ 10. For n = 3 and n = 4 the present results are compared with those of Green et al. [1,2] and Loreau et al. [3]

On the (E⊗e)- Jahn-Teller conical intersections in the 3p(Eʹ) and 3d(E") Rydberg electronic states of triatomic hydrogen

The static and dynamic aspects of the Jahn-Teller(JT) interactions in the 3p(E′) and 3d(E")Rydberg electronic states of H3 are analyzed theoretically. The static aspects are discussed based on recent ab initio quantum chemistry results, and the dynamic aspects are examined in terms of the vibronic spectra and nonradiative decay behavior of these states. The adiabatic potential-energysurfaces of these degenerate electronic states are derived from extensive ab initio calculations. The calculated adiabatic potential-energysurfaces are diabatized following our earlier study on this system in its 2p(E′)ground electronic state. The nuclear dynamics on the resulting conically intersecting manifold of electronic states is studied by a time-dependent wave-packet approach. Calculations are performed both for the uncoupled and coupled state situations in order to understand the importance of nonadiabatic interactions due to the JT conical intersections in these excited Rydberg electronic states