Search results for " Spectra"
showing 10 items of 709 documents
Algebraic approach to vibrational spectra of tetrahedral molecules. First order infrared intensity model.
1995
International audience; The algebraic approach we have proposed to describe the vibrational stretching modes of polyatomic molecules (Leroy and Michelot, J. Mol. Spectrosc. 151, 71–96 (1992); Can. J. Phys. 72, 274–289 (1994)) is applied to the silane molecule for up to seven quanta. We then suggest a form of the dipole operator adapted to the (n000) local states by combining the strength of group theory method with the necessity of a compact formulation.
Unitary Approach to Vibrational Spectra of Tetrahedral Molecules: Generalized Infrared Intensity Model.
1997
International audience; In this paper we further extend a previous formalism, the construction of a dipole function adapted to tetrahedral molecules. The extension is based on an algebraic construction of symmetrized tensor operators through unitary algebra and point group symmetry. We prove that this generalization allows us to find the particular formalism that has been established and satisfactorily tested in a previous paper (C. Leroy et al., J. Mol. Spectrosc. 175, 289–295 (1996)).
gA -driven shapes of electron spectra of forbidden β decays in the nuclear shell model
2017
The evolution of the shape of the electron spectra of 16 forbidden ${\ensuremath{\beta}}^{\ensuremath{-}}$ decays as a function of ${g}_{\mathrm{A}}$ was studied using the nuclear shell model in appropriate single-particle model spaces with established, well-tested nuclear Hamiltonians. The $\ensuremath{\beta}$ spectra of $^{94}\mathrm{Nb}({6}^{+})\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}^{94}\mathrm{Mo}({4}^{+})$ and $^{98}\mathrm{Tc}({6}^{+})\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}^{98}\mathrm{Ru}({4}^{+})$ were found to depend strongly on ${g}_{\mathrm{A}}$, which makes them excellent candidates for the determination of the effective value of ${g}_{\mathrm{A}}$ wit…
Second-forbidden nonunique β− decays of Na24 and Cl36 assessed by the nuclear shell model
2020
We have performed a systematic study of the $logft$ values, shape factors, and electron spectra for the second-forbidden nonunique ${\ensuremath{\beta}}^{\ensuremath{-}}$ decays of $^{24}\mathrm{Na}({4}^{+})\ensuremath{\rightarrow}^{24}\mathrm{Mg}({2}^{+})$ and $^{36}\mathrm{Cl}({2}^{+}){\ensuremath{\rightarrow}}^{36}\mathrm{Ar}({0}^{+})$ transitions under the framework of the nuclear shell model. We have performed the shell model calculations in the $sd$ model space, using more recent microscopic effective interactions such as Daejeon16, chiral N3LO, and JISP16. These interactions are derived from the no-core shell model wave functions using Okubo-Lee-Suzuki transformation. For comparison,…
APOGEE Data Releases 13 and 14: Stellar Parameter and Abundance Comparisons with Independent Analyses
2018
Data from the SDSS-IV / Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have been released as part of SDSS Data Releases 13 (DR13) and 14 (DR14). These include high resolution H-band spectra, radial velocities, and derived stellar parameters and abundances. DR13, released in August 2016, contained APOGEE data for roughly 150,000 stars, and DR14, released in August 2017, added about 110,000 more. Stellar parameters and abundances have been derived with an automated pipeline, the APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP). We evaluate the performance of this pipeline by comparing the derived stellar parameters and abundances to those inferred from opti…
Synchrotron-based Fourier transform spectra of the ν23 and ν24 IR bands of hexamethylenetetramine C6N4H12
2015
Abstract Hexamethylenetetramine (HMT), C6N4H12 is a spherical top with nine IR-active modes. Because of its relevance for astrophysics, we recorded the absorption spectra in the full range of its fundamental bands. In total, we detected eight fundamental bands and recently published the rotational analysis of the four most intense bands ( ν 19 , ν 20 , ν 21 , ν 22 ) located in the 1000–1500 cm−1 range as a support for astronomical searches (Pirali et al., 2014). While the CH stretch modes are unresolved broad features, in this article we report the analysis of the two remaining fundamental bands exhibiting rotationally resolved structures: ν 23 –GS and ν 24 –GS located at about 820 cm−1 and…
The Zoo of emission lines in the spectrum of Cir X-1 observed by XMM-Newton
2007
We present the preliminary analysis of a 10 ks XMM-Newton EPIC/pn observation of Cir X-1 immediately after the zero phase. The continuum emission is modeled using a blackbody component partially absorbed by neutral matter probably located around the binary system. We detect a forest of emission lines associated to highly ionized ions.
Microcalorimeter/EBIT measurements of X-ray spectra of highly charged ions
2001
Spectra of highly charged Ar, Kr, Xe and Fe ions, produced in an Electron Beam Ion Trap (EBIT), have been recorded in a broad X-ray energy band (0.2 keV to 10 keV) with a microcalorimeter detector. The first analysis of the Kr spectra has been completed and most of the spectral lines have been identified as transitions of B- to Al-like Kr. Line intensity ratios of Fe XVII have been measured and compared with theoretical models.
Stochastic Response Of Fractionally Damped Beams
2014
Abstract This paper aims at introducing the governing equation of motion of a continuous fractionally damped system under generic input loads, no matter the order of the fractional derivative. Moreover, particularizing the excitation as a random noise, the evaluation of the power spectral density performed in frequency domain highlights relevant features of such a system. Numerical results have been carried out considering a cantilever beam under stochastic loads. The influence of the fractional derivative order on the power spectral density response has been investigated, underscoring the damping effect in reducing the power spectral density amplitude for higher values of the fractional de…
New measurements and global analysis of chloromethane in the region from 0 to 1800cm−1
2003
Abstract New high resolution Fourier transform spectra of pure 12CH335Cl and 12CH337Cl isotopomers of chloromethane have been recorded in Wuppertal covering the region from 600 to 3800 cm−1. New rotational transitions within the v2=1, v5=1, and v3=2 states have been measured at Lille. A first global analysis of the lower four band systems of the molecule (700–1800 cm−1) is reported. The model was based on an effective Hamiltonian and dipole moment expressed in terms of irreducible tensor operators. A common set of 125 effective hamiltonian parameters (sixth order) has been adjusted to fit simultaneously some 11 000 IR data for each of the isotopomers including 153 mm wave data for 12 CH3 35…