The high-resolution spectroscopy of dissociating molecules

1990 ◽  
Vol 332 (1625) ◽  
pp. 297-307 ◽  
Keyword(s):  
High Resolution ◽  
Energy Flow ◽  
Energy State ◽  
Reaction Dynamics ◽  
Theoretical Models ◽  
Spectroscopic Studies ◽  
High Resolution Spectroscopy ◽  
Bond Breaking ◽  
Vibrational Levels ◽  
Dynamical Constraints

Results from spectroscopic studies of the vibrational levels of dissociating molecules and from state-selected, state-resolved photofragmentation spectroscopy are presented. The extent of energy flow among the modes of a molecule is explored through the couplings, or lack thereof, revealed by high-resolution spectroscopy. The dynamics of energy flow during bond breaking are revealed by photofragment excitation spectroscopy and by product energy state distributions. These completely resolved data provide sensitive tests of dynamical constraints such as vibrational or rotational adiabaticity and thus of theoretical models for unimolecular reaction dynamics.

scholarly journals High Resolution Spectroscopy With Molecular Beams and Tunable Lasers

1998 ◽  
Vol 18 (1-2) ◽  
pp. 1-11 ◽  
Author(s):  
R. Vetter ◽  
P. Luc ◽  
C. Amiot
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Diatomic Molecules ◽  
Reaction Dynamics ◽  
Molecular Beams ◽  
Tunable Lasers ◽  
High Resolution Spectroscopy ◽  
Absorption Bands ◽  
Quantum Numbers ◽  
Laser Techniques

High resolution Doppler-free laser techniques are used in beam experiments to improve the spectroscopic description of complex diatomic molecules. The case of TiO is considered here for its implication in reaction dynamics studies and its interest in Astrophysics. Two absorption bands in the visible have been analyzed: B3Π−X3 Δ(1−0) and c1Φ−a1 Δ(0−0). Owing to accurate wavenumber measurements, it has been possible to extend the analysis to high rotational quantum numbers and to carry out detailed spectroscopic calculations. They show that a careful revisiting of the TiO electronic structure is necessary.

scholarly journals JD 16 – Spectroscopy With Large Telescopes of Chemically Peculiar Stars: Preface

1998 ◽  
Vol 11 (2) ◽  
pp. 645-645
Author(s):  
M. Takada-Hidai ◽  
J. Zverko
Keyword(s):  
High Resolution ◽  
Spectroscopic Studies ◽  
High Resolution Spectroscopy ◽  
Stellar Spectroscopy ◽  
Chemically Peculiar ◽  
Peculiar Stars ◽  
New Findings ◽  
Chemically Peculiar Stars ◽  
Large Telescopes ◽  
Near Future

The Keck 10-m telescope has begun to produce many new findings in a field of stellar spectroscopy with the help of the High Resolution Spectrograph (HIRES). The other large telescopes such as the Subaru, VLT, and Gemini are now being constructed and expected to perform high-resolution spectroscopy in a near future within several years or so. These highresolution spectroscopic studies will be carried out based on studies which have been made mainly with existing telescopes with aperture smaller than 4 m.

scholarly journals Atmospheric characterization of the ultra-hot Jupiter MASCARA-2b/KELT-20b

2019 ◽  
Vol 628 ◽  
pp. A9 ◽  
Author(s):  
N. Casasayas-Barris ◽  
E. Pallé ◽  
F. Yan ◽  
G. Chen ◽  
S. Kohl ◽  
...  
Keyword(s):  
High Resolution ◽  
Wavelength Range ◽  
Atmospheric Chemistry ◽  
Signal To Noise Ratio ◽  
Theoretical Models ◽  
High Resolution Spectroscopy ◽  
Additional Absorption ◽  
Hot Jupiters ◽  
Gas Heating ◽  
First Time

Ultra-hot Jupiters orbit very close to their host star and consequently receive strong irradiation, causing their atmospheric chemistry to be different from the common gas giants. Here, we have studied the atmosphere of one of these particular hot planets, MASCARA-2b/KELT-20b, using four transit observations with high resolution spectroscopy facilities. Three of these observations were performed with HARPS-N and one with CARMENES. Additionally, we simultaneously observed one of the transits with MuSCAT2 to monitor possible spots in the stellar surface. At high resolution, the transmission residuals show the effects of Rossiter-McLaughlin and centre-to-limb variations from the stellar lines profiles, which we have corrected to finally extract the transmission spectra of the planet. We clearly observe the absorption features of CaII, FeII, NaI, Hα, and Hβ in the atmosphere of MASCARA-2b, and indications of Hγ and MgI at low signal-to-noise ratio. In the case of NaI, the true absorption is difficult to disentangle from the strong telluric and interstellar contamination. The results obtained with CARMENES and HARPS-N are consistent, measuring an Hα absorption depth of 0.68 ± 0.05 and 0.59 ± 0.07%, and NaI absorption of 0.11 ± 0.04 and 0.09 ± 0.05% for a 0.75 Å passband, in the two instruments respectively. The Hα absorption corresponds to ~1.2 Rp, which implies an expanded atmosphere, as a result of the gas heating caused by the irradiation received from the host star. For Hβ and Hγ only HARPS-N covers this wavelength range, measuring an absorption depth of 0.28 ± 0.06 and 0.21 ± 0.07%, respectively. For CaII, only CARMENES covers this wavelength range measuring an absorption depth of 0.28 ± 0.05, 0.41 ± 0.05 and 0.27 ± 0.06% for CaII λ8498Å, λ8542Å and λ8662Å lines, respectively. Three additional absorption lines of FeII are observed in the transmission spectrum by HARPS-N (partially covered by CARMENES), measuring an average absorption depth of 0.08 ± 0.04% (0.75 Å passband). The results presented here are consistent with theoretical models of ultra-hot Jupiters atmospheres, suggesting the emergence of an ionised gas on the day-side of such planets. Calcium and iron, together with other elements, are expected to be singly ionised at these temperatures and be more numerous than its neutral state. The Calcium triplet lines are detected here for the first time in transmission in an exoplanet atmosphere.

scholarly journals Sub-Doppler High-Resolution Spectroscopy of 15V Band of CS2 and the Zeeman Effect

1995 ◽  
Vol 15 (2-4) ◽  
pp. 131-143 ◽  
Author(s):  
Atsushi Doi ◽  
Masaya Ohtsuka ◽  
Kiyoshi Nishizawa ◽  
Masaaki Baba ◽  
Hajime Katô
Keyword(s):  
High Resolution ◽  
Zeeman Effect ◽  
Orbit Interaction ◽  
High Resolution Spectroscopy ◽  
Spin Orbit ◽  
Excitation Spectra ◽  
Main Band ◽  
Spin Orbit Interaction ◽  
Vibrational Levels ◽  
Almost All

Excitation spectra and the Zeeman spectra of CS2 in the region of 31320-31445 cm-1were measured with sub-Doppler resolution. Observed rotational lines were classified to 14 series of lines (vibronic bands) and were named by the wavenumbers of their band origins. The 31344.9 band is the strongest one and is assigned as the main band of the V1B20v20(K=0) – X1∑g+ 0000 transition. Most of the extra bands may be allowed by the vibronic interaction between the V1B20v20(K=0) level and singlet levels, which are mostly high vibrational levels of the 1A1(X1∑g+) state. The Zeeman splittings are observed for several lines in almost all bands. These may be originating from the spin-orbit interaction between the rotational levels, which have accidentally nearly the same energy, of the 1A1(X1∑g+) state and the 3A2 (3Δu ) or/and 3B2 (3Δu) state.

Synchrotron radiation and long path cryogenic cells: New tools and results for modelling chlorinated compounds absorption in the 8-12µm atmospheric window

2020 ◽  
Author(s):  
Laurent Manceron
Keyword(s):  
High Resolution ◽  
Atmospheric Chemistry ◽  
Broad Band ◽  
Spectroscopic Studies ◽  
Heterogeneous Reactions ◽  
Chlorine Nitrate ◽  
Synchrotron Source ◽  
Fourier Transform Spectrometry ◽  
Vibrational Levels ◽  
Stratospheric Clouds

<p> </p><p><strong>Anusanth Anantharajah<sup>a</sup>, Fridolin Kwabia Tchana<sup>a</sup>, Jean-Marie Flaud<sup>a</sup> , Pascale Roy<sup>b</sup> and Laurent Manceron<sup>b,c</sup></strong></p><ul><li>a- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, <br>Université de Paris et Université Paris-Est Créteil, Institut Pierre Simon Laplace, <br>61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France.</li> <li>b- Synchrotron SOLEIL, AILES Beamline, L’Orme des Merisiers, Saint-Aubin F-91192, France.</li> <li>c-  Sorbonne Université, CNRS, MONARIS, UMR 8233, 4 place Jussieu, F-75005 Paris, France. </li> </ul><p> </p><p>Nitryl chloride (ClNO<sub>2</sub>) and Chlorine Nitrate are molecules of great interest for atmospheric chemistry since these are produced by heterogeneous reactions, in the marine troposphere, between NaCl sea-salt aerosols or ClO and gaseous N<sub>2</sub>O<sub>5</sub> [1,2], and on polar stratospheric clouds, between N<sub>2</sub>O<sub>5</sub> and solid HCl [3,4].</p><p> </p><p>Many high-resolution spectroscopic studies in the microwave and mid-infrared regions are available. However, these molecules present low-lying vibrational levels and thus numerous hot bands in the regions of the NOx stretching and bending mode absorptions in the 8-12 µm atmospheric transparency window which could serve for remote sensing and quantification of these species.</p><p>Fourier Transform Spectrometry is a useful technique to observe broad band high resolution spectra (0.001 cm<sup>-1</sup>) of these molecules and a significant advantage is gained by combining interferometry with the high brightness of a synchrotron source [5]. At SOLEIL we have developed specific instrumentation to study such reactive molecules and a few results concerning chlorine-containing compounds will be presented.</p><ol><li>B. J. Finlayson-Pitts, M. J. Ezell, and J. N. Pitts Jr, Nature <strong>337</strong>, 241-244 (1989).</li> <li>W. Behnke, V. Scheer, and C. Zetzsch, J. Aerosol Sci. <strong>24</strong>, 115-116 (1993).</li> <li>. M. A. Tolbert, M. J. Rossi, and D. M. Golden, Science <strong>240</strong>, 1018-1021 (1988).</li> <li>M. T. Leu, Geophys. Res. Lett. <strong>15</strong>, 851-854 (1988).</li> <li> J-M. Flaud, A. Anantharajah, F. Kwabia Tchana, L. Manceron, J. Orphal, G. Wagner, and M. Birk, J Quant Spectrosc Radiat Transf <strong>224</strong>, 217-221 (2019).</li> </ol><p> </p>

scholarly journals The flux-weighted gravity-luminosity relation of Galactic classical Cepheids

2020 ◽  
Vol 640 ◽  
pp. A113
Author(s):  
M. A. T. Groenewegen
Keyword(s):  
High Resolution ◽  
Effective Temperature ◽  
Spectroscopic Studies ◽  
High Resolution Spectroscopy ◽  
Spectral Energy ◽  
Pulsation Period ◽  
Instability Strip ◽  
Energy Distributions ◽  
Classical Cepheids ◽  
Good Agreement

The flux-weighted gravity-luminosity relation (FWGLR) is investigated for a sample of 477 classical Cepheids (CCs), including stars that have been classified in the literature as such but are probably not. The luminosities are taken from the literature, based on the fitting of the spectral energy distributions (SEDs) assuming a certain distance and reddening. The flux-weighted gravity (FWG) is taken from gravity and effective temperature determinations in the literature based on high-resolution spectroscopy. There is a very good agreement between the theoretically predicted and observed FWG versus pulsation period relation that could serve in estimating the FWG (and log g) in spectroscopic studies with a precision of 0.1 dex. As was known in the literature, the theoretically predicted FWGLR relation for CCs is very tight and is not very sensitive to metallicity (at least for LMC and solar values), rotation rate, and crossing of the instability strip. The observed relation has a slightly different slope and shows more scatter (0.54 dex). This is due both to uncertainties in the distances and to the pulsation phase averaged FWG values. Data from future Gaia data releases should reduce these errors, and then the FWGLR could serve as a powerful tool in Cepheid studies.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

1995 ◽  
Vol 53 ◽  
pp. 524-525
Author(s):  
Z. Horita ◽  
D. J. Smith ◽  
M. Furukawa ◽  
M. Nemoto ◽  
R. Z. Valiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Grain Boundaries ◽  
Energy State ◽  
High Energy ◽  
Grain Structure ◽  
Boundary Structure ◽  
Solid Solution Alloy ◽  
Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

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