- ID:
- ivo://CDS.VizieR/J/A+A/591/A110
- Title:
- ^15^NH_2_ amidogen radical rotational spectrum
- Short Name:
- J/A+A/591/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The determination of isotopic ratios in interstellar molecules is a powerful probe of chemical routes leading to their formation. In particular the ^14^N/^15^N abundance ratio of nitrogen-bearing species provides information on possible fractionation mechanisms. Up to now there is no accurate determination of this ratio in the ISM for the amidogen radical, NH_2_. This work aimed at determining rotational frequencies of ^15^NH_2_ in order to enable its astronomical detection, which will help to understand the formation mechanisms of nitrogen hydrides in the ISM. Complementary synchrotron-based broadband far-infrared and high resolution submillimeter-wave frequency measurements have been performed to investigate the pure rotational spectrum of the ^15^NH_2_ species. The first spectroscopic study of the ^15^N-isotopologue of the amidogen radical yielded an accurate set of molecular parameters. Accurate frequencies are now available for ^15^NH_2_ up to 7THz (with N''>=13) and dedicated astronomical searches can be undertaken.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/230/26
- Title:
- NH_2_CH_2_CN transition frequencies
- Short Name:
- J/ApJS/230/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is important to study possible precursors of amino acids such as glycine to enable future searches in interstellar space. Aminoacetonitrile (NH_2_CH_2_CN) is one of the most feasible molecules for this purpose. This molecule was already detected toward Sgr B2(N). Aminoacetonitrile has a few low-lying vibrational excited states, and transitions within these states may be found in space. In this study, the pure-rotational transitions in the three lowest vibrational states in the 80-450 GHz range have been assigned and analyzed. It was found to be very important to include Coriolis coupling between the two lowest vibrational fundamentals, while the third one was unperturbed. The partition function was evaluated considering these new results.
- ID:
- ivo://CDS.VizieR/J/ApJ/735/111
- Title:
- NH_3_ line lists at high temperatures
- Short Name:
- J/ApJ/735/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present line lists for ammonia (NH_3_) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for 12 temperatures (300{deg}C-1300{deg}C in 100{deg}C intervals and 1370{deg}C) and each line list covers the 740-2100cm^-1^ range, which includes the majority of the {nu}_2_ umbrella bending mode region (11um) and the {nu}_4_ asymmetric bending mode region (6.2um). We also demonstrate the useful technique of obtaining empirical lower state energies from a set of spectra recorded at different sample temperatures. Using our NH_3_ spectra, we have estimated lower state energies (E_Low_ in cm^-1^) and our values have been incorporated into the line lists along with calibrated wavenumbers (\tilde{nu} in cm^-1^) and calibrated line intensities (S' in cm/molecule) for each line. We expect our hot NH_3_ line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/430/725
- Title:
- N II effective collision strengths
- Short Name:
- J/A+A/430/725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The effective collision strengths are presented in this table for all transitions among the lowest 41 fine-structure levels belonging to the 2s(2)2p(2), 2s2p(3) and 2s(2)2p3l(l=s,p,d) configurations of N II. These have been calculated using the R-matrix method. Each fine-structure level is assigned an index number in Table 1 of the manuscript ranging from 1 to 41. These index values are used here in Table 2 to refer to particular transitions, eg. Index 1-3 denotes the transition 2s(2)2p(2)3PE(J=0)-2s(2)2p(2)3PE(J=2). The effective collision strengths for each transition are presented in rows for a number of electron temperatures ranging from log10(T)=2.00 to log10(T)=5.50.
- ID:
- ivo://CDS.VizieR/J/A+A/387/1135
- Title:
- NII effective recombination coefficients
- Short Name:
- J/A+A/387/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We calculate effective recombination coefficients for the formation of selected lines of NII. New photoionization data are computed which accurately map the near threshold resonances and are used to derive recombination coefficients for principal quantum numbers, n<=15, including radiative and dielectronic recombination. Cascading from higher states is included, allowing for the effects of finite electron density in a hydrogenic approximation. The effects of population in the excited states of the recombining ion are investigated.
- ID:
- ivo://CDS.VizieR/J/A+AS/119/99
- Title:
- [Ni I] & [Ni II] transition probabilities
- Short Name:
- J/A+AS/119/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New radiative transition probabilities have been calculated for forbidden lines of astrophysical interest in Ni I and Ni II. The accuracy of the transition probability scales is established on the basis of two independent calculations performed with the approximately relativistic Hartree-Fock (HFR) and SUPERSTRUCTURE (SST) codes. Both physical models take into account the most important configuration interaction (CI) and relativistic effects.
- ID:
- ivo://CDS.VizieR/J/ApJS/211/20
- Title:
- NiI transition probability measurements
- Short Name:
- J/ApJS/211/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Atomic transition probability measurements for 371 NiI lines in the UV through near-IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrograph are combined with published radiative lifetimes to determine these transition probabilities. Generally good agreement is found in comparisons to previously reported NiI transition probability measurements. Use of the new echelle spectrograph, independent radiometric calibration methods, and independent data analysis routines enable a reduction of systematic errors and overall improvement in transition probability uncertainty over previous measurements. The new NiI data are applied to high-resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ni abundances. Lines covering a wide range of wavelength and excitation potential are used to search for non-LTE effects.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A123
- Title:
- NiXI electron collisional excitation
- Short Name:
- J/A+A/566/A123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new large-scale R-matrix scattering calculation for electron collisional excitation of Ni XI, carried out with the intermediate-coupling frame transformation method (ICFT). The target includes all the main configurations up to n=4, and is a significant improvement over earlier R-matrix (only three n=3 configurations) and distorted-wave (DW) calculations. We find significant enhancements in the collision strengths of many of the strong transitions to the n=3,4 levels. They are due to the resonances that arise within the present large-scale target. This results in significant increases in the predicted intensities of the UV and visible forbidden lines within the 3s^2^ 3p^5^ 3d configuration, the strong EUV lines that result from the decays of the 3s^2^ 3p^5^ 3d levels to the ground state, and the decays from the n=4 levels, which are visible in the soft X-rays. We find good agreement between predicted and observed line intensities in the EUV. With the present atomic data, lines from Ni XI can reliably be used for plasma diagnostics. We also revise some level energies and suggest a few new possible identifications.
- ID:
- ivo://CDS.VizieR/J/A+A/475/393
- Title:
- NiXI radiative and excitation rates
- Short Name:
- J/A+A/475/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we report calculations for energy levels, radiative rates and excitation rates for transitions in NiXI. The GRASP (General-purpose Relativistic Atomic Structure Package) and FAC (Flexible Atomic Code) have been adopted for calculating energy levels and radiative rates, and the Dirac Atomic R-matrix Code (DARC) has been used to determine the excitation rates. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 250 levels of NiXI. Additionally, lifetimes are also reported for all levels. However, results for excitation rates are presented only for transitions among the lowest 17 levels.
- ID:
- ivo://CDS.VizieR/J/A+A/488/365
- Title:
- NiXIX effective collision strengths
- Short Name:
- J/A+A/488/365
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we report electron impact collision strengths and excitation rates for transitions among the lowest 89 levels of NiXIX. The Dirac atomic R-matrix code (DARC) is adopted for the calculations of collision strengths and subsequently the effective collision strengths. Collision strengths for resonance transitions among 89 levels arising from the (1s^2^) 2s^2^2p^6^, 2s^2^2p^5^3l, 2s2p^6^3l, 2s^2^2p^5^4l, and 2s2p^6^4l configurations of NiXIX are reported over a wide energy range below 250Ryd. Additionally, effective collision strengths for all 3916 transitions among the 89 levels are listed over a wide temperature range below 10^7^K. Comparisons are made among different calculations and the accuracy of the data is assessed. Finally, comparisons between theoretical and experimental intensity ratios of some prominent lines of NiXIX are discussed.
