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High-resolution Spectroscopy (high-resolution + spectroscopy)

Distribution by Scientific Domains
Physics and Astronomy55%

Selected Abstracts

New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2005
S. Ciroi
ABSTRACT We present new important results about the intermediate-type Seyfert galaxy Mrk 315, recently observed through optical imaging and integral-field spectroscopy. Broad-band images were used to study the morphology of the host galaxy, narrow-band H, images to trace the star-forming regions, and middle-band [O iii] images to evidence the distribution of the highly ionized gas. Some extended emission regions were isolated and their physical properties studied by means of flux-calibrated spectra. High-resolution spectroscopy was used to separate different kinematic components in the velocity fields of gas and stars. Some peculiar features characterize this apparently undisturbed and moderately isolated active galaxy. Such features, already investigated by other authors, are re-analysed and discussed in the light of these new observations. The most relevant results we obtained are: the multitiers structure of the disc; the presence of a quasi-ring of regions with star formation much higher than previous claims; a secondary nucleus confirmed by a stellar component kinematically decoupled by the main galaxy; a new hypothesis about the controversial nature of the long filament, initially described as hook shaped, and more likely made of two independent filaments caused by interaction events between the main galaxy and two dwarf companions. [source]

Prospects of stellar abundance studies from near-IR spectra observed with the E-ELT

ASTRONOMISCHE NACHRICHTEN, Issue 4 2010
N. Ryde
Abstract In 2006 ESO Council authorized a Phase B study of a European AO-telescope with a 42 m segmented primary with a 5-mirror design, the E-ELT. Several reports and working groups have already presented science cases for an E-ELT, specifically exploiting the new capabilities of such a large telescope. One of the aims of the design has been to find a balance in the performances between an E-ELT and the James Webb Space Telescope, JWST. Apart from the larger photon-collecting area, the strengths of the former is the higher attainable spatial and spectral resolutions. The E-ELT AO system will have an optimal performance in the near-IR, which makes it specially advantageous. High-resolution spectroscopy in the near-infrared has, however, not been discussed much. This paper aims at filling that gap, by specifically discussing spectroscopy of stellar (mainly red giant), photospheric abundances. Based on studies in the literature of stellar abundances, at the needed medium to high spectral resolutions in the near-infrared (0.8,2.4 ,m), I will try to extrapolate published results to the performance of the E-ELT and explore what could be done at the E-ELT in this field. A discussion on what instrument characteristics that would be needed for stellar abundance analyses in the near-IR will be given (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

NMR of peptides and proteins in oriented membranes

CONCEPTS IN MAGNETIC RESONANCE, Issue 3 2002
Francesca M. Marassi
Abstract Solid-state NMR spectroscopy is used to determine the structures of membrane peptides and proteins in lipid bilayers. The methodology for membrane protein structure determination using solid-state NMR of oriented lipid bilayer samples is outlined. Recent developments in recombinant bacterial expression systems for the preparation of isotopically labeled membrane proteins, pulse sequences for high-resolution spectroscopy, and structural indices that guide the structure assembly process greatly extend the capabilities of the technique. © 2002 Wiley Periodicals, Inc. Concepts in Magn Reson 14, 212,224, 2002. [source]

Continuously tunable S and C+L bands ultra wideband erbium-doped fiber ring laser

LASER PHYSICS LETTERS, Issue 8 2009
Q. Wang
Abstract This paper presents an ultra wideband tunable silicabased erbium doped fiber ring laser (EDFRL) that can be continuously tuned in S and C+L bands from 1475 to 1619 nm. It is the first time that a fiber ring laser's tuning range reaches 144 nm using a standard silica-based C-band erbium-doped fiber as gain media. In the laser configuration two isolators are used in the fiber loop for suppressing the ASE in C-band and elevating the lasing gain in S-band. As a result the available lasing wavelength is extended toward the shorter wavelength of the gain bandwidth. The optimized erbium-doped fiber length, output coupling ratio and pumping laser power have been obtained through experimental study. This ring fiber laser has simple configuration, low threshold, flat laser spectral distribution and high signal-to-ASE-noise ratio. The laser will have many potential applications in fiber sensor wavelength interrogation, high-resolution spectroscopy and fiber optic communications. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Orbital parameters, masses and distance to , Centauri determined with the Sydney University Stellar Interferometer and high-resolution spectroscopy

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2005
J. Davis
ABSTRACT The bright southern binary star , Centauri (HR 5267) has been observed with the Sydney University Stellar Interferometer (SUSI) and spectroscopically with the European Southern Observatory Coude Auxiliary Telescope and Swiss Euler telescope at La Silla. The interferometric observations have confirmed the binary nature of the primary component and have enabled the determination of the orbital parameters of the system. At the observing wavelength of 442 nm the two components of the primary system have a magnitude difference of 0.15 ± 0.02. The combination of interferometric and spectroscopic data gives the following results: orbital period 357.00 ± 0.07 d, semimajor axis 25.30 ± 0.19 mas, inclination 674 ± 03, eccentricity 0.821 ± 0.003, distance 102.3 ± 1.7 pc, primary and secondary masses M1=M2= 9.1 ± 0.3 M, and absolute visual magnitudes of the primary and secondary M1V=,3.85 ± 0.05 and M2V=,3.70 ± 0.05, respectively. The high degree of accuracy of the results offers a fruitful starting point for future asteroseismic modelling of the pulsating binary components. [source]

The design of excitation pulses for spin systems using optimal control theory: With application to NMR spectroscopy

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 5 2009
Naum I. Gershenzon
Abstract This paper considers the use of optimal control theory in designing radio frequency excitation pulses for magnetic spin systems satisfying Bloch dynamics. Such pulses are required in applications of nuclear magnetic resonance to initially transfer sample magnetization vectors to the transverse plane. Once transferred, signals released by nuclei as they respond to a static magnetic field normal to the transverse plane are then analyzed and interpreted. Continuous time deterministic optimal control theory is employed to determine time-dependent pulse amplitudes and frequencies that minimize the distance between final magnetization vectors and a chosen target vector. Pulses are designed to excite a range of resonant frequencies and to tolerate miscalibration errors in applied fields. The model presented permits a unified treatment of the control problem as considered by a variety of authors, and a thorough mathematical analysis of the existence, and characteristics of, optimal excitation pulses. Practical numerical algorithms for designing optimal pulses are given, and the effectiveness of the algorithms is illustrated by comparing the pulses that they generate with those commonly used in high-resolution spectroscopy. Copyright © 2008 John Wiley & Sons, Ltd. [source]

X-ray spectroscopy of early-type stars: The present and the future

ASTRONOMISCHE NACHRICHTEN, Issue 2 2008
G. Rauw
Abstract XMM-Newton and Chandra have boosted our knowledge about the X-ray emission of early-type stars (spectral types OB and Wolf-Rayet). However, there are still a number of open questions that need to be addressed in order to fully understand the X-ray spectra of these objects. Many of these issues require high-resolution spectroscopy or monitoring of a sample of massive stars. Given the moderate X-ray brightness of these targets, rather long exposure times are needed to achieve these goals. In this contribution, we review our current knowledge in this field and present some hot topics that could ideally be addressed with XMM-Newton over the next decade. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Understanding High-Resolution Spectra of Nonrigid Molecules Using Group Theory

CHEMPHYSCHEM, Issue 4 2010
Melanie Schnell Dr.
Abstract Permutation-inversion group theory has developed to become an important tool in the high-resolution spectroscopy of nonrigid molecules. This large class of molecules is very intriguing to study. Small molecules such as ammonia or Na3 are known to be nonrigid. With increasing size, however, several large-amplitude motions are possible in a molecule, and can even interact with each other. The high-resolution spectra of nonrigid molecules are known to be quite complicated and very rich in information. Details about the molecule and its internal dynamics can be extracted, such as the molecular structure, the character of the chemical bonds, and the barrier heights to internal rotation and their dependence on the chemical bonds. However, due to the nonrigidity of the molecule and the complexity of such spectra, their analysis is usually quite challenging. Theoretical methods are needed for their prediction and analysis. This Review concentrates on permutation-inversion group theory and its usefulness for the analysis of high-resolution spectra of nonrigid molecules, which is examined in more detail using different examples. In a separate section, a special aspect of molecular symmetry is discussed: the breakdown of symmetry principles. Special emphasis is placed on the breakdown of space inversion symmetry (parity violation) in chiral molecules and its possible implications in high-resolution spectroscopy. [source]

Single Dibenzoterrylene Molecules in an Anthracene Crystal: Spectroscopy and Photophysics

CHEMPHYSCHEM, Issue 8 2007
Aurélien A. L. Nicolet
Abstract We study single dibenzoterrylene molecules in an anthracene single crystal at 1.4 K in two insertion sites at 785.1 and 794.3 nm. The single-molecule zero-phonon lines are narrow (about 30 MHz), intense (the detected fluorescence rates at saturation reach 100,000 counts,s,1), and very photostable. The intersystem-crossing yield is extremely low (10,7 or lower). All of these features are hallmarks of an excellent system for high-resolution spectroscopy and nanoscale probing at cryogenic temperatures. [source]