Search Results
Distance of Hi-GAL sources
2021, Mège, P., Russeil, D., Zavagno, A., Elia, D., Molinari, S., Brunt, C.M., Butora, R., Cambresy, L., Di Giorgio, A.M., Fenouillet, T., Fukui, Y., Lambert, J.C., Makai, Z., Merello, M., Meunier, J.C., Molinaro, M., Moreau, C., Pezzuto, S., Poulin, Y., Schisano, E., Schuller, F.
Aims. Distances are key to determining the physical properties of sources. In the Galaxy, large (> 10 000) homogeneous samples of sources for which distance are available, covering the whole Galactic distance range, are still missing. Here we present a catalog of velocity and distance for a large sample (> 100 000) of Hi-GAL compact sources. Methods. We developed a fully automatic Python package to extract the velocity and determine the distance. To assign a velocity to a Hi-GAL compact source, the code uses all the available spectroscopic data complemented by a morphological analysis. Once the velocity is determined, if no stellar or maser parallax distance is known, the kinematic distance is calculated and the distance ambiguity (for sources located inside the Solar circle) is solved with the H I self-absorption method or from distance-extinction data. Results. Among the 150 223 compact sources of the Hi-GAL catalog, we obtained a distance for 124 069 sources for the 5σ catalog (and 128 351 sources for the 3σ catalog), where σ represents the noise level of each molecular spectrum used for the line detections made at 5σ and 3σ to produce the respective catalogs. © P. Mège et al. 2021.
Experimental strategies for optical pump - Soft x-ray probe experiments at the LCLS
2014, McFarland, B.K., Berrah, N., Bostedt, C., Bozek, J., Bucksbaum, P.H., Castagna, J.C., Coffee, R.N., Cryan, J.P., Fang, L., Farrell, J.P., Feifel, R., Gaffney, K.J., Glownia, J.M., Martinez, T.J., Miyabe, S., Mucke, M., Murphy, B., Natan, A., Osipov, T., Petrovic, V.S., Schorb, S., Schultz, T., Spector, L.S., Swiggers, M., Tarantelli, F., Tenney, I., Wang, S., White, J.L., White, W., Gühr, M.
Free electron laser (FEL) based x-ray sources show great promise for use in ultrafast molecular studies due to the short pulse durations and site/element sensitivity in this spectral range. However, the self amplified spontaneous emission (SASE) process mostly used in FELs is intrinsically noisy resulting in highly fluctuating beam parameters. Additionally timing synchronization of optical and FEL sources adds delay jitter in pump-probe experiments. We show how we mitigate the effects of source noise for the case of ultrafast molecular spectroscopy of the nucleobase thymine. Using binning and resorting techniques allows us to increase time and spectral resolution. In addition, choosing observables independent of noisy beam parameters enhances the signal fidelity.
Remote system for detection of low-levels of methane based on photonic crystal fibres and wavelength modulation spectroscopy
2009, Carvalho, J.P., Lehmann, H., Bartelt, H., Magalhes, F., Amezcua-Correa, R., Santos, J.L., Roosbroeck, J.V., Arajo, F.M., Ferreira, L.A., Knight, J.C.
In this work we described an optical fibre sensing system for detecting low levels of methane. The properties of hollow-core photonic crystal fibres are explored to have a sensing head with favourable characteristics for gas sensing, particularly in what concerns intrinsic readout sensitivity and gas diffusion time in the sensing structure. The sensor interrogation was performed applying the Wavelength Modulation Spectroscopy technique, and a portable measurement unit was developed with performance suitable for remote detection of low levels of methane. This portable system has the capacity to simultaneously interrogate four remote photonic crystal fibre sensing heads. Copyright © 2009 J. P. Carvalho et al.
Towards time resolved core level photoelectron spectroscopy with femtosecond x-ray free-electron lasers
2008, Pietzsch, A., Föhlisch, A., Beye, M., Deppe, M., Hennies, F., Nagasono, M., Suljotil, E., Wurth, W., Gahl, C., Dörich, K., Melnikov, A.
We have performed core level photoelectron spectroscopy on a W(110) single crystal with femtosecond XUV pulses from the free-electron laser at Hamburg (FLASH). We demonstrate experimentally and through theoretical modelling that for a suitable range of photon fluences per pulse, time-resolved photoemission experiments on solid surfaces are possible. Using FLASH pulses in combination with a synchronized optical laser, we have performed femtosecond time-resolved core-level photoelectron spectroscopy and observed sideband formation on the W 4f lines indicating a cross correlation between femtosecond optical and XUV pulses. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
The HITRAN2020 molecular spectroscopic database
2022, Gordon, I.E., Rothman, L.S., Hargreaves, R.J., Hashemi, R., Karlovets, E.V., Skinner, F.M., Conway, E.K., Hill, C., Kochanov, R.V., Tan, Y., Wcisło, P., Finenko, A.A., Nelson, K., Bernath, P.F., Birk, M., Boudon, V., Campargue, A., Chance, K.V., Coustenis, A., Drouin, B.J., Flaud, J.M., Gamache, R.R., Hodges, J.T., Jacquemart, D., Mlawer, E.J., Nikitin, A.V., Perevalov, V.I., Rotger, M., Tennyson, J., Toon, G.C., Tran, H., Tyuterev, V.G., Adkins, E.M., Baker, A., Barbe, A., Canè, E., Császár, A.G., Dudaryonok, A., Egorov, O., Fleisher, A.J., Fleurbaey, H., Foltynowicz, A., Furtenbacher, T., Harrison, J.J., Hartmann, J.M., Horneman, V.M., Huang, X., Karman, T., Karns, J., Kassi, S., Kleiner, I., Kofman, V., Kwabia-Tchana, F., Lavrentieva, N.N., Lee, T.J., Long, D.A., Lukashevskaya, A.A., Lyulin, O.M., Makhnev, V.Yu., Matt, W., Massie, S.T., Melosso, M., Mikhailenko, S.N., Mondelain, D., Müller, H.S.P., Naumenko, O.V., Perrin, A., Polyansky, O.L., Raddaoui, E., Raston, P.L., Reed, Z.D., Rey, M., Richard, C., Tóbiás, R., Sadiek, I., Schwenke, D.W., Starikova, E., Sung, K., Tamassia, F., Tashkun, S.A., Vander Auwera, J., Vasilenko, I.A., Vigasin, A.A., Villanueva, G.L., Vispoel, B., Wagner, G., Yachmenev, A., Yurchenko, S.N.
The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition.