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J/A+A/376/356       Diatomic molecules collisional rates     (Chandra+, 2001)

Collisional rates for vib-rotational transitions in diatomic molecules. Chandra S., Sharma A.K. <Astron. Astrophys. 376, 356 (2001)> =2001A&A...376..356C
ADC_Keywords: Atomic physics Keywords: molecular data - stars: circumstellar matter Abstract: A number of diatomic molecules have been found in vibrationally excited states in several cosmic objects. The molecules in vibrationally excited states provide valuable information about the physical conditions prevailing near star forming regions and in circumstellar envelopes of late-type stars. To analyze the spectrum of such molecules, some of the important parameters required are the collisional rate coefficients for vib-rotational transitions in the molecule. Currently, knowledge of collisional rate coefficients is very poor. Here, we discuss a method for calculating the collisional rate coefficients for vib-rotational transitions in a diatomic molecule, where the colliding partner H2 is considered as a structureless particle. This method is quite good for high temperatures (usually found in star-forming regions and in circumstellar envelopes of late-type stars), but may be questioned for low temperatures. As an example, calculations for the CS molecule at 500K for three vibrational states are presented. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 21 118 Energy, statistical weight, vibrational quantum number, and rotational quantum number of energy levels table3.dat 39 6786 Collisional rate coefficients for the transition from the upper to the lower level
See also: J/A+AS/114/175 : Einstein A-coefficients in CS transitions (Chandra+ 1995) J/A+AS/117/557 : Einstein coefficients for CO transitions (Chandra+ 1996) J/A+AS/131/137 : Einstein A-Coefficients in SiC2 transitions (Chandra+ 1998) J/A+AS/142/113 : C3H2 and SiC2 collisional rates (Chandra+, 2000) J/A+A/376/333 : Einstein A-coefficients for C3H4 (Sharma+, 2001) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- No Serial number 5- 13 F9.4 cm-1 E Energy 15- 16 I2 --- SWeigth Statistical weight 18 I1 --- v Vibrational quantum number of energy level 20- 21 I2 --- J Rotational quantum number of energy level
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1 A1 --- --- [(] (1) 2 I1 --- vu Vibrational quantum number of upper level (1) 3 A1 --- --- [,] (1) 5- 6 I2 --- ju Rotational quantum number of upper level (1) 7 A1 --- --- [)] (1) 9- 11 A3 --- --- [⟹] (1) 13 A1 --- --- [(] (1) 14 I1 --- vl Vibrational quantum number of lower level (1) 15 A1 --- --- [,] (1) 17- 18 I2 --- jl Rotational quantum number of lower level (1) 19 A1 --- --- [)] (1) 22- 29 E8.4 cm3/s Rate Collisional rate coefficient from u to l 32- 34 I3 --- u Upper level 37- 39 I3 --- l Lower level
Note (1): Name of the transition between the upper level with vibrational quantum number vu and rotational quantum number ju and the lower level with vibrational quantum number vl and rotational quantum number jl, (vu, ju) ⟹ (vl, jl)
Acknowledgements: S. Chandra <chandrasuresh@123india.com>
(End) Patricia Bauer [CDS] 27-Aug-2001
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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