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Title: Rate constants for the formation of SiO by radiative association

Journal Article · · Monthly Notices of the Royal Astronomical Society
 [1];  [1]; ORCiD logo [2];  [3];  [4]
  1. Pennsylvania State Univ., Reading, PA (United States). Dept. of Physics
  2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States). Inst. for Theoretical Atomic, Molecular and Optical Physics (ITAMP)
  3. Univ. of Georgia, Athens, GA (United States). Dept. of Physics and Astronomy. Center for Simulational Physics
  4. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States). Inst. for Theoretical Atomic, Molecular and Optical Physics (ITAMP); Queen's Univ., Belfast, Northern Ireland (United Kingdom). Centre for Theoretical Atomic Molecular and Optical Physics (CTAMOP). School of Mathematics and Physics
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Accurate molecular data for the low-lying states of SiO are computed and used here to calculate rate constants for radiative association (RA) of Si and O. Einstein A-coefficients are also calculated for transitions between all of the bound and quasi-bound levels for each molecular state. The radiative widths are used together with elastic tunnelling widths to define effective RA rate constants which include both direct and indirect (inverse pre-dissociation) formation processes. The indirect process is evaluated for two kinetic models which represent limiting cases for astrophysical environments. The first case scenario assumes an equilibrium distribution of quasi-bound states and would be applicable whenever collisional and/or radiative excitation mechanisms are able to maintain the population. The second case scenario assumes that no excitation mechanisms are available which corresponds to the limit of zero radiation temperature and zero atomic density. Rate constants for SiO formation in realistic astrophysical environments would presumably lie between these two limiting cases.

Research Organization:
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Pennsylvania State Univ., Reading, PA (United States); Univ. of Georgia, Athens, GA (United States)
Sponsoring Organization:
USDOE; National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)
Grant/Contract Number:
PHY-1503615; NNX16AF09G
OSTI ID:
1523823
Journal Information:
Monthly Notices of the Royal Astronomical Society, Vol. 471, Issue 2; ISSN 0035-8711
Publisher:
Royal Astronomical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 11 works
Citation information provided by
Web of Science

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Cited By (5)

Semiclassical methods for calculating radiative association rate constants for different thermodynamic conditions: Application to formation of CO, CN, and SiN journal June 2019
Photodissociation of CS from Excited Rovibrational Levels journal April 2018
Dicarbon Formation in Collisions of Two Carbon Atoms journal April 2019
Quadrupole Radiative Association in the Early Universe journal August 2019
Dicarbon formation in collisions of two carbon atoms text January 2019

Figures / Tables (11)

Table 1(p. 3)table Table 1
Figure 1(p. 4)figure Figure 1
Table 2(p. 4)table Table 2
Figure 2(p. 5)figure Figure 2
Figure 3(p. 6)figure Figure 3
Figure 4(p. 6)figure Figure 4
Figure 5(p. 7)figure Figure 5
Figure 6(p. 7)figure Figure 6
Figure 7(p. 7)figure Figure 7
Figure 8(p. 8)figure Figure 8
Table 3(p. 9)table Table 3

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