scholarly journals A surface-hopping method for semiclassical calculations of cross sections for radiative association with electronic transitions

2017 ◽  
Vol 147 (9) ◽  
pp. 094308 ◽  
Author(s):  
Péter Szabó ◽  
Magnus Gustafsson
Keyword(s):  
Cross Sections ◽  
Electronic Transitions ◽  
Surface Hopping ◽  
Radiative Association

Radiative association for the formation of MgO

2020 ◽  
Vol 500 (2) ◽  
pp. 2496-2502
Author(s):  
Tianrui Bai ◽  
Zhi Qin ◽  
Linhua Liu
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Low Density ◽  
Mechanical Method ◽  
Hot Gas ◽  
Radiative Association ◽  
Quantum Mechanical Method ◽  
Formation And Evolution ◽  
The Cross ◽  
Increasing Temperature

ABSTRACT The radiative association process for the formation of magnesium oxide (MgO) may be of great importance due to its frequent occurrence in the low-density and dust-poor astrochemical environments. In this work, the cross-sections and rate coefficients for the A1Π → X1Σ+, ${\rm X}^1\Sigma ^+\, \rightarrow \, {\rm A}^1\Pi$, D1Δ → A1Π, a3Π → e3Σ−, ${\rm X}^1\Sigma ^+\, \rightarrow \, {\rm X}^1\Sigma ^+$, and A1Π → A1Π radiative association processes of forming MgO are theoretically estimated. The cross-sections for the transitions between the different states are obtained by using the semiclassical method for direct contributions and the Breit–Wigner theory as a complement for resonance contributions. For the transitions between the same states, the quantum mechanical method is used. The rate coefficients are then obtained from the cross-sections for the temperatures in the range of 10–10 000 K and the results are found to vary from 4.69 $\times \, 10^{-16}$ to 6.27 $\times \, 10^{-14}$ cm3 s−1. For temperatures lower than around 693 K, the rate coefficients for the A1Π → X1Σ+ process are dominant, which indicates this process is the most efficient way of producing MgO at low temperatures. However, the rate coefficients for the D1Δ → A1Π process go through a rapid increase with increasing temperature and become dominant at higher temperatures. For other processes, their rate coefficients are several orders of magnitude lower than those for the two processes mentioned above. The results can be used to further investigate the formation and evolution of MgO in low density and hot gas close to the photosphere of evolved oxygen-rich stars.

SPECTRAL SIGNATURES OF ACETONE VAPOR FROM ULTRAVIOLET TO MILLIMETER WAVELENGTHS

2008 ◽  
Vol 18 (03) ◽  
pp. 627-637 ◽  
Author(s):  
R. E. PEALE ◽  
A. V. MURAVJOV ◽  
C. J. FREDRICKSEN ◽  
G. D. BOREMAN ◽  
H. SAXENA ◽  
...  
Keyword(s):  
Cross Sections ◽  
Near Infrared ◽  
Electronic Transitions ◽  
Acetone Vapor ◽  
Mid Infrared ◽  
Spectral Signatures ◽  
Millimeter Wavelengths ◽  
Peak Absorption ◽  
Vibrational Overtones ◽  
Available Technology

This paper presents comparative analysis of different wavelength ranges for the spectroscopic detection of acetone vapor. We collected and analyzed original absorption line spectra arising from electronic transitions in the ultraviolet, near-infrared vibrational overtones, mid-infrared fundamentals, THz torsional modes, and mm-wave rotational transitions. Peak absorption cross sections of prominent spectral features are determined. The relative merit of each spectral range for sensing is considered, taking into account the absorption strength, available technology, and possible interferences.

Refined theoretical study of radiative association: Cross sections and rate constants for the formation of SiN

2012 ◽  
Vol 137 (10) ◽  
pp. 104301 ◽  
Author(s):  
Magnus Gustafsson ◽  
Sergey V. Antipov ◽  
Jan Franz ◽  
Gunnar Nyman
Keyword(s):  
Cross Sections ◽  
Rate Constants ◽  
Theoretical Study ◽  
Radiative Association

Formation of CO+ by radiative association II

2020 ◽  
Vol 492 (3) ◽  
pp. 3794-3802
Author(s):  
Martina Zámečníková ◽  
Magnus Gustafsson ◽  
Gunnar Nyman ◽  
Pavel Soldán
Keyword(s):  
Oxygen Atom ◽  
Cross Sections ◽  
Rate Coefficient ◽  
Total Rate ◽  
Temperature Range ◽  
Sn 1987A ◽  
Semiclassical Methods ◽  
Radiative Association ◽  
The Cross

ABSTRACT Radiative association of an oxygen atom with a carbon cation is investigated using quantal and semiclassical methods. The total rate coefficient for spontaneous radiative association of O(2s22p4, 3P) with C+(2s22p, 2P) on the doublet manifold is determined from the corresponding cross-sections. The cross-sections for the ${\rm 1}^2\, \Sigma ^-\rightarrow {\rm A}^2\Pi$, ${\rm 2}^2\, \Sigma ^-\rightarrow {\rm A}^2\Pi$, and ${\rm C}^2\, \Delta \rightarrow {\rm A}^2\Pi$ continuum-bound processes are calculated either semiclassically, in combination with the Breit–Wigner approach, or fully quantum mechanically. In the temperature range 10–10 000 K, our recommended total rate coefficient, obtained from these calculations and the data of Zámečníková et al. (2019), slowly increases from 7.5 × 10−18 cm3s−1 to 2.1 × 10−17 cm3s−1. Corresponding aspects of the CO+ and CO formations in SN 1987A are discussed.

scholarly journals Formation of CO+ by radiative association

2019 ◽  
Vol 489 (2) ◽  
pp. 2954-2960 ◽  
Author(s):  
Martina Zámečníková ◽  
Pavel Soldán ◽  
Magnus Gustafsson ◽  
Gunnar Nyman
Keyword(s):  
Cross Sections ◽  
Formation Rate ◽  
Transition Dipole Moment ◽  
Basis Set ◽  
Rate Coefficients ◽  
Charge Transfer Reaction ◽  
Transition Dipole ◽  
Sn 1987A ◽  
Radiative Association ◽  
Structure Calculations

ABSTRACT We theoretically estimate formation rate coefficients for CO+ through the radiative association of C+(2P) with O(3P). In 1989, Petuchowski et al. claimed radiative association to be the most important route for CO+ formation in SN 1987A. In 1990, Dalgarno, Du and You challenged this claim. Therefore, in this study, we improve previous estimates of the radiative association rate coefficients for forming CO+ from C+(2P) and O(3P). To do this, we perform quantum mechanically based perturbation theory calculations as well as semiclassical calculations, which are combined with Breit–Wigner theory in order to add the effect of shape resonances. We explicitly include four electronic transitions. The required potential energy and transition dipole-moment curves are obtained through large basis set multireference configuration interaction electronic structure calculations. We report cross-sections and from these we obtain rate coefficients in the range of 10 –10 000 K, finding that the CO+ formation rate coefficient is larger than the previous estimate by Dalgarno et al. Still our results support their claim that in SN 1987A, CO is mainly formed through radiative association and not through the charge transfer reaction CO+ + O → CO + O+ as earlier suggested by Petuchowski et al.

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