Measuring The Difference In Collisional Interaction Of Hcn/hnc With He At Low Temperatures Using The Cpuf Technique

The T$_{2}$ time of HCN and HNC in He was measured at low temperatures using chirped pulse Fourier transform millimeter wave spectroscopy, to compare to scattering calculations and to investigate the difference of interaction between the two structural isomers. These molecules are commonly observed in the interstellar medium (ISM), where their abundance ratio can be used to elucidate conditions within an interstellar environment. Within these environments, they are expected to collide with He and H$_{2}$, which could lead to non-thermal excitation. Previous ab initio calculations of the collisions with He and H2 with HCN and HNC have shown that the rates for HNC with these colliders are much greater, despite their similarities in structure. We have performed CPUF (Chirped pulse in Uniform Flow) experiments to measure the difference in T$_{2}$ of HCN and HNC at cold temperatures in He. The J=1-0 transitions of HCN and HNC were observed in under CRESU (Reaction Kinetics in Uniform Supersonic Flow) conditions using cold flows of He. Pulsed laser photolysis of vinyl cyanide was used to produce HCN and HNC under comparable conditions. The T$_{2}$ time was fit directly from the free induction decays of these experiments at different temperatures, which is directly comparable to the linewidth in the frequency domain. This was then compared to pressure broadening cross sections produced from close coupling scattering calculations performed on ab initio potential energy surfaces. We find that there is a difference in interaction of HCN and HNC with He at low temperatures and will discuss the impacts this may have for observing these species in the ISM

Chirped pulse microwave spectroscopy on methyl butanoate

The microwave spectrum of methyl butanoate has been taken from 8-18 GHz using a chirped pulse spectrometer. This molecule is a model biofuel, and its thermal decomposition products are of interest due to its many dissociation channels. As a preliminary step before such pyrolysis studies, we have examined the jet cooled spectrum of methyl butanoate in a chirped pulse spectrometer, which shows a very rich spectrum. Several conformers have been identified, each with tunneling splittings in the methyl ester group due to internal rotation. These spectra have been fit to obtain rotational constants, relative populations, and methyl rotor barriers for each conformational isomer. The results of these studies are compared to high level calculations

DETECTING BRANCHING RATIOS OF CHEMICAL REACTIONS AT ASTROPHYSICALLY RELEVANT TEMPERATURES USING CHIRPED PULSE MILLIMETER WAVE SPECTROSCOPY IN CONTINUOUS CRESU FLOWS

The reactions of molecules in interstellar space occur over a wide range of temperatures, down to 10 K or colder. The study of gas-phase chemical reactions at these temperatures has been difficult until the development and implementation of the CRESU (French acronym for Reaction Kinetics in Uniform Supersonic Flow) technique in Rennes. Reaction kinetics at temperatures as low as 6 K has been monitored, but product branching ratios have not yet been measured at such low temperatures. The recent development of the CPUF (Chirped Pulse in Uniform supersonic Flow) technique has shown that chirped pulse spectroscopy can be combined with uniform supersonic flows, so that the branching ratios of chemical reactions can be examined. This has been extended to the continuous CRESU flows at Rennes, taking advantage of the deep averaging capabilities of chirped pulse Fourier transform spectrometers complementing the continuous flows. An E-band chirped pulse Fourier transform spectrometer has been incorporated into a current CRESU instrument to detect reaction products. The effects that the uniform flow has on molecular spectra have been characterized in this frequency range. Reactions of ethylene and cyanide radicals have been monitored using pulsed laser photolysis for product detection. The branching ratios of reactions will be discussed, as well as future directions of the instrument

ROTATIONAL SPECTROSCOPY AND CONFORMATIONAL STUDIES OF 4-PENTYNENITRILE, 4-PENTENENITRILE, AND GLUTARONITRILE

The pure rotational spectra of 4-pentynenitrile, 4-pentenenitrile, and glutaronitrile were acquired using chirped pulse Fouirer transform microwave spectroscopy. 4-pentynenitrile and 4-pentenenitrile are the recombination products of two resonance stabilized radicals, propargyl + cyanomethyl or allyl + cyanomethyl, respectively, and are thus anticipated to be significant among the more complex nitriles in Titan's atmosphere. Indeed, these partially unsaturated alkyl cyanides have been found in laboratory analogs of tholins and are also expected to have interesting photochemistry. The optimized structures of all conformers below predicted energies of 500 wn were calculated for each molecule. Both of the conformers, trans and gauche, for 4-pentynenitrile have been identified and assigned. Five conformers were assigned in 4-pentenenitrile. The eclipsed conformers, with respect to the vinyl group, dominate the spectrum but some population was found in the syn conformers including the syn-gauche conformer, calculated to be 324 wn above the global minimum. The glutaronitrile spectrum contained only the two conformers below 500 wn, with reduced amount of the gauche trans conformer. The assigned spectra and structural assignments will be presented

Prospectus, March 28, 1984

ACHIEVEMENT AWARD WINNERS; News Digest; Rayburn enjoys chairmanship; Illinois primary winners; PC Happenings: Nursing workshop scheduled, EMT refresher workshop scehduled, Basic nutrition is series focus, Vietnam veterans to meet, Art department to host guest artist, Students compete in office careers; Illinois recycling week April 22-28; Cans worth money; Parkland fall registration; StuGo discusses changes; Creative Corner...Especially for you!!: Love, No Defeat, Bums, To God, I am to you to feel so worn and tired..., The sun\u27s golden rays warm me through and through...; Reflections and Contemplations; Traditional Polish folk art reflects strong sense of nationalism; Classifieds; \u27Ice Pirates\u27 fails miserably; Summer film release dates; \u27Mister Heartbreak\u27--lyrics a treasure; Walt Disney starts production on \u27OZ\u27; Paul Heath--dynamic Ice Capades star; White Sox should take easy division; Palmer and Dickerson with Christie Clinic run; Chicago Simeon wins AA tournament; Class AA Boys Basketball Results; All-Tournament Selections; Scientist helps players sharpen up; Cobra basketball award-winners named; Recruiting important part; Our students are student-athletes, not athlete-students ; Women softball leagues starting up; Centennial loses chance at state titlehttps://spark.parkland.edu/prospectus_1984/1027/thumbnail.jp

Motherhood as Contested Ideological Terrain: Essentialist and Queer Discourses of Motherhood at Play in Female–Female Co-mothers’ Talk

Framed by relational dialectics theory (Baxter), this investigation considered the meaning(s) of motherhood in female–female co-motherhood. Analysis identified two competing discourses: (1) discourse of essential motherhood (DEM) and (2) discourse of queer motherhood (DQM). Speakers’ invocation of the DEM reinscribes the mainstream US cultural discourse that children can have only one authentic (i.e., biological) mother, whereas invocation of the DQM denaturalizes the DEM’s presumptions of authentic motherhood as biological, interrupts monomaternalism, destabilizes the patriarch, and troubles the equation of biological with moral motherhood. Whereas interpenetrations of the DEM and DQM were typically sites of adversarial discursive struggle, in a few instances, the DEM and DQM rose above their antagonistic relationship, combining to create new meanings of motherhood

CSO BROADBAND MOLECULAR LINE SURVEYS II: INTIAL CORRELATION ANALYSIS RESULTS FOR COMPLEX ORGANIC MOLECULES

Author Institution: Emory University, Department of Chemistry, Atlanta, Georgia 30322As was presented in the previous talk, we have conducted 25 broadband line surveys of interstellar sources in the $\lambda$=1.3 mm band using the Caltech Submillimeter Observatory. Using the results from the spectral analysis of these observations, the influence of physical environment on molecular complexity can be examined. Our broader research goal is to improve astrochemical models to the point where accurate predictions of complex molecular inventory can be made based on the physical and chemical environment of a given source. The CSO observations include a statistically-significant sample of sources, cover a range of physical environments, and target selected frequency windows containing transitions from a set of known complex organic molecules. We are now analyzing these line surveys to search for correlations between the relative abundances of organic molecules and the physical properties of the source (i.e. temperature, density, mass, etc.), as well as correlations between sets of molecules. Here we present the results from the initial quantitative analysis of these surveys, as well as chemical trends that have been determiend. The implications of these results for astrochemical models will also be discussed

Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A. Reimer, L.C. Reye

A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope

Globular clusters with their large populations of millisecond pulsars (MSPs) are believed to be potential emitters of high-energy gamma-ray emission. Our goal is to constrain the millisecond pulsar populations in globular clusters from analysis of gamma-ray observations. We use 546 days of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to study the gamma-ray emission towards 13 globular clusters. Steady point-like high-energy gamma-ray emission has been significantly detected towards 8 globular clusters. Five of them (47 Tucanae, Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices $(0.7 < \Gamma <1.4)$ and clear evidence for an exponential cut-off in the range 1.0-2.6 GeV, which is the characteristic signature of magnetospheric emission from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral indices $(1.0 < \Gamma < 1.7)$, however the presence of an exponential cut-off can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC 6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral properties. From the observed gamma-ray luminosities, we estimate the total number of MSPs that is expected to be present in these globular clusters. We show that our estimates of the MSP population correlate with the stellar encounter rate and we estimate 2600-4700 MSPs in Galactic globular clusters, commensurate with previous estimates. The observation of high-energy gamma-ray emission from a globular cluster thus provides a reliable independent method to assess their millisecond pulsar populations that can be used to make constraints on the original neutron star X-ray binary population, essential for understanding the importance of binary systems in slowing the inevitable core collapse of globular clusters.Comment: Accepted for publication in A&A. Corresponding authors: J. Kn\"odlseder, N. Webb, B. Pancraz