Uptake Coefficients of Some Volatile Organic Compounds by Soot and Their Application in Understanding Particulate Matter Evolution in Aircraft Engine Exhaust Plumes

To assist microphysical modeling on particulate matter (PM) evolution emitted from aircraft engines, uptake coefficients of some volatile organic compounds on soot were experimentally determined in this study. The determined values vary from (1.0±0.1)×10⁻⁶ for water-miscible propylene glycol to (2.5±0.1)×10⁻⁵ for 2,6-dimethylnaphthalene, a polycyclic aromatic hydrocarbon. An inverse power-law correlation between uptake coefficient on soot and solubility in water was observed. Using the correlation, microphysical simulations were performed for the exhaust plume evolution from an idling aircraft, and we found that the model-predicted volatile PM composition on soot is comparable with those results from past field measurements.United States. Department of Defense (Contract W912HQ-08-C-0052

Vibrationally Resolved Decay Width of Interatomic Coulombic Decay in HeNe

We investigate the ionization of HeNe from below the He 1s3p excitation to the He ionization threshold. We observe HeNe$^+$ ions with an enhancement by more than a factor of 60 when the He side couples resonantly to the radiation field. These ions are an experimental proof of a two-center resonant photoionization mechanism predicted by Najjari et al. [Phys. Rev. Lett. 105, 153002 (2010)]. Furthermore, our data provide electronic and vibrational state resolved decay widths of interatomic Coulombic decay (ICD) in HeNe dimers. We find that the ICD lifetime strongly increases with increasing vibrational state.Comment: 7 pages, 5 figure

The Impact of Climate Policy on U.S. Aviation

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).We evaluate the impact of an economy-wide cap-and-trade policy on U.S. aviation taking the American Clean Energy and Security Act of 2009 (H.R.2454) as a representative example. We use an economywide model to estimate the impact of H.R. 2454 on fuel prices and economic activity, and a partial equilibrium model of the aviation industry to estimate changes in aviation carbon dioxide (CO2) emissions and operations. Between 2012 and 2050, with reference demand growth benchmarked to ICAO/GIACC (2009) forecasts, we find that aviation emissions increase by 130%. In our climate policy scenarios, emissions increase by between 97% and 122%. A key finding is that, under the core set of assumptions in our analysis, H.R. 2454 reduces average fleet efficiency, as increased air fares reduce demand and slow the introduction of new aircraft. Assumptions relating to the sensitivity of aviation demand to price changes, and the degree to which higher fuel prices stimulate advances in the fuel efficiency of new aircraft play an important role in this result.U.S. Federal Aviation Administration Office of Environment and Energy under FAA Award Number: 06HCHNEHMIT, Amendment Nos. 018 and 028. ErichHBecker Foundation. The Joint Program on the Science and Policy of Global Change is funded by the U.S. Department of Energy and a consortium of government and industrial sponsors

Interatomic-Coulombic-decay-induced recapture of photoelectrons in helium dimers

We investigate the onset of photoionization shakeup induced interatomic Coulombic decay (ICD) in He2 at the He+*(n = 2) threshold by detecting two He+ ions in coincidence. We find this threshold to be shifted towards higher energies compared to the same threshold in the monomer. The shifted onset of ion pairs created by ICD is attributed to a recapture of the threshold photoelectron after the emission of the faster ICD electron.Comment: 5 Pages, 2 Figure

A measurement of the evolution of Interatomic Coulombic Decay in the time domain

During the last 15 years a novel decay mechanism of excited atoms has been discovered and investigated. This so called ''Interatomic Coulombic Decay'' (ICD) involves the chemical environment of the electronically excited atom: the excitation energy is transferred (in many cases over long distances) to a neighbor of the initially excited particle usually ionizing that neighbor. It turned out that ICD is a very common decay route in nature as it occurs across van-der-Waals and hydrogen bonds. The time evolution of ICD is predicted to be highly complex, as its efficiency strongly depends on the distance of the atoms involved and this distance typically changes during the decay. Here we present the first direct measurement of the temporal evolution of ICD using a novel experimental approach.Comment: 6 pages, 4 figures, submitted to PR

Simulation of the thermally induced austenitic phase transition in NiTi nanoparticles

The reverse martensitic ("austenitic") transformation upon heating of equiatomic nickel-titanium nanoparticles with diameters between 4 and 17 nm is analyzed by means of molecular-dynamics simulations with a semi-empirical model potential. After constructing an appropriate order parameter to distinguish locally between the monoclinic B19' at low and the cubic B2 structure at high temperatures, the process of the phase transition is visualized. This shows a heterogeneous nucleation of austenite at the surface of the particles, which propagates to the interior by plane sliding, explaining a difference in austenite start and end temperatures. Their absolute values and dependence on particle diameter are obtained and related to calculations of the surface induced size dependence of the difference in free energy between austenite and martensite.Comment: 6 pages, 4 figures, accepted for publication in "The European Physical Journal B

Ion impact induced Interatomic Coulombic Decay in neon and argon dimers

We investigate the contribution of Interatomic Coulombic Decay induced by ion impact in neon and argon dimers (Ne$_2$ and Ar$_2$) to the production of low energy electrons. Our experiments cover a broad range of perturbation strengths and reaction channels. We use 11.37 MeV/u S$^{14+}$, 0.125 MeV/u He$^{1+}$, 0.1625 MeV/u He$^{1+}$ and 0.150 MeV/u He$^{2+}$ as projectiles and study ionization, single and double electron transfer to the projectile as well as projectile electron loss processes. The application of a COLTRIMS reaction microscope enables us to retrieve the three-dimensional momentum vectors of the ion pairs of the fragmenting dimer into Ne$^{q+}$/Ne$^{1+}$ and Ar$^{q+}$/Ar$^{1+}$ (q = 1, 2, 3) in coincidence with at least one emitted electron

Two-particle interference of electron pairs on a molecular level

We investigate the photo-doubleionization of $H_2$ molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasi-particle consisting of both electrons (i.e. the "dielectron") does. The work highlights the fact that non-local effects are embedded everywhere in nature where many-particle processes are involved

Heterogeneous reactions in aircraft gas turbine engines

[1] One-dimensional flow models and unity probability heterogeneous rate parameters are used to estimate the maximum effect of heterogeneous reactions on trace species evolution in aircraft gas turbines. The analysis includes reactions on soot particulates and turbine/nozzle material surfaces. Results for a representative advanced subsonic engine indicate the net change in reactant mixing ratios due to heterogeneous reactions is <10 À6 for O 2 , CO 2 , and H 2 O, and <10 À10 for minor combustion products such as SO 2 and NO 2 . The change in the mixing ratios relative to the initial values is < 0.01%. Since these estimates are based on heterogeneous reaction probabilities of unity, the actual changes will be even lower. Thus, heterogeneous chemistry within the engine cannot explain the high conversion of SO 2 to SO 3 whicsome wake models require to explain the observed levels of vola tile aerosols. Furthermore, turbine heterogeneous processes will not effect exhaust NO x or NO y levels

The Partnership for AiR Transportation Noise and Emissions Reduction,

Abstract We evaluate the impact of an economy-wide cap-and