J/A+A/492/257 Collisional excitation of water in warm media (Faure+, 2008)
Collisional excitation of water in warm astrophysical media.
I. Rate coefficients for rovibrationally excited states
Faure A., Josselin E.
<Astron. Astrophys. 492, 257 (2008)>
=2008A&A...492..257F 2008A&A...492..257F
ADC_Keywords: Atomic physics
Keywords: molecular data ; molecular processes ; ISM: molecules
Abstract:
The interpretation of water line emission from infrared and
submillimetre observations requires a detailed knowledge of
collisional rate coefficients over a wide range of levels and
temperatures.
We attempt to determine rotational and rovibrational rate coefficients
for H2O colliding with both H2 and electrons in warm, molecular
gas.
Pure rotational rates are derived by extrapolating published data
using a new method partly based on the information (phase space)
theory of Levine and co-workers. Ro-vibrational rates are obtained
using vibrational relaxation data available in the literature and by
assuming a complete decoupling of rotation and vibration.
Results. Rate coefficients were obtained for the lowest 824
ro-vibrational levels of H2O in the temperature range 200-5000K. Our
data is expected to be accurate to within a factor of ∼5 for the
highest rates (>10-11cm3/s). Smaller rates, including the
ro-vibrational ones, should be generally accurate to within an order
of magnitude. As a first application of this data, we show that
vibrationally excited water emission observed in evolved stars is
expected to be at least partly excited by means of collisions.
Description:
*Downward* pure rotational and ro-vibrational rates are provided for
the 5 lowest vibrational levels of H2O and 11 temperatures (from 200
to 5000K). This corresponds to all possible transitions among the
lowest 824th levels of H2O below 5000cm-1. Upward rates can be
computed using the detailed balance relation (see article).
Rate files are denoted as
coll-ph2o-h2.dat and coll-oh2o-h2.dat
for para-H20 and ortho-H20 colliding with H2, respectively, and
coll-ph2o-e.dat and coll-oh2o-e.dat
for para-H20 and ortho-H20 colliding with electrons, respectively.
The labelling of para- and ortho-H2O levels in the rate files
correspond to the labelling in files ortho-H2O.levels and
para-H2O.levels. For vibrational levels the normal mode notation
(v1v2v3) is employed (v1 corresponds to symmetric stretch, v2 to
bending and v3 to antisymmetric stretch).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 100 6 List of files
levels/* . 2 *Energy levels of ortho-H2O and para-H2O
rates/* . 4 *De-excitation rates of para-H2O and ortho-H2O
in collision with H2
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Note on levels/*: Each level file contains the 11-lines header:
# ! Energy levels of para-H2O
# ! Ref:
# ! Tennyson et al. J. Phys. Chem. Ref. Data, 30, 735-831 (2001)
# ! Energy unit :
# ! cm^-1
# ! Number of columns :
# 6
# ! Number of Lines :
# 413
# ! Level Energy J Ka Kc vib.
Note on rates/*: Each rate file contains the 5-lines header:
# ! NUMBER OF COLLISION TEMPERATURES
# 11
# ! COLLISION TEMPERATURES
# 200.0 400.0 800.0 1200.0 1600.0 2000.0 2500.0 3000.0 3500.0 4000.0
5000.0
# ! TRANS + UP + LOW + RATE COEFFS(cm^3 s^-1)
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See also:
VI/119 : High accuracy computed water line list - BT2 (Barber+, 2006)
J/A+A/472/1029 : (De)excitation rates of H2O by H2 (Faure+, 2007)
J/A+A/493/687 : Rotational excitation of formaldehyde by H2 (Faure+, 2009)
J/MNRAS/399/425 : (De)excitation rates of ortho-NH3 and para-NH3 (Faure+, 2009)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- FileName File name
28-100 A73 --- Title Title of the file
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Byte-by-byte Description of file(#): levels/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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2- 4 I03 --- ilev Level number
7- 17 F11.6 cm-1 elev Energy value
21- 22 I2 --- J J quantum number
26- 27 I2 --- Ka Ka quantum number
31- 32 I2 --- Kc Kc quantum number
35- 37 I03 --- v1v2v3 v1v2v3 quantum numbers (G1)
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Byte-by-byte Description of file(#): rates/*
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Bytes Format Units Label Explanations
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1- 5 I5 --- itrans Transition number
9- 11 I03 --- i [2/413] Initial level
15- 17 I03 --- f [1/412] Final level
19- 26 E8.2 cm3/s k200 Rate coefficient at 200K
28- 35 E8.2 cm3/s k400 Rate coefficient at 400K
37- 44 E8.2 cm3/s k800 Rate coefficient at 800K
46- 53 E8.2 cm3/s k1200 Rate coefficient at 1200K
55- 62 E8.2 cm3/s k1600 Rate coefficient at 1600K
64- 71 E8.2 cm3/s k2000 Rate coefficient at 2000K
73- 80 E8.2 cm3/s k2500 Rate coefficient at 2500K
82- 89 E8.2 cm3/s k3000 Rate coefficient at 3000K
91- 98 E8.2 cm3/s k3500 Rate coefficient at 3500K
100-107 E8.2 cm3/s k4000 Rate coefficient at 4000K
109-116 E8.2 cm3/s k5000 Rate coefficient at 5000K
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Acknowledgements:
Alexandre Faure <afaure(at)obs.ujf-grenoble.fr>
Global notes:
Note (G1): The vibrational level is written as a 3-digit number v1v2v3,
e.g. 010 or 120. It represents vibrational quanta in normal modes
v1 (symmetric stretch), v2 (bending) and v3 (antisymmetric stretch),
respectively.
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History:
* 28-Nov-2008: Original files
* 27-Aug-2009: Some files removed (from author):
levels: o-h2o.001.levels and p-h2o.001.levels)
rates: o-h2o-h2-001-*, h2o-h2-001-*,
o-h2o-e-001-*, p-h2o-e-001-*)
* 25-Feb-2010: All original files removed, and replaced by NEW FILES
(End) Alexandre Faure [LAOG, France], Patricia Vannier [CDS] 18-Feb-2010