J/ApJ/818/120 H2 d3Πu excitation by electron impact (Liu+, 2016)
Spectra, emission yields, cross sections, and kinetic energy distributions of
hydrogen atoms from H2 X1Σg+-d3Πu excitation
by electron impact.
Liu X., Shemansky D.E., Yoshii J., Johnson P.V., Malone C.P., Ajello J.M.
<Astrophys. J., 818, 120 (2016)>
=2016ApJ...818..120L 2016ApJ...818..120L (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: molecular data; molecular processes
Abstract:
Electron-impact excitation of H2 triplet states plays an important
role in the heating of outer planet upper thermospheres. The
d3Πu state is the third ungerade triplet state, and the
d3Πu-a3Σg+ emission is the largest cascade channel
for the a3Σg+ state. Accurate energies of the
d3Πu-(v, J) levels are calculated from an ab initio potential
energy curve. Radiative lifetimes of the d3Πu(v,J) levels are
obtained by an accurate evaluation of the d3Πu-a3Σg+
transition probabilities. The emission yields are determined from
experimental lifetimes and calculated radiative lifetimes and are
further verified by comparing experimental and synthetic
d3Πu-a3Σg+ spectra at 20eV impact energy. Spectral
analysis revealed that multipolar components beyond the dipolar term
are required to model the X1Σg+-d3Πu excitation,
and significant cascade excitation occurs at the d3Πu (v=0,1)
levels. Kinetic energy (Ek) distributions of H atoms produced via
predissociation of the 3Πu state and the
d3Πu-a3Σg+-b3Σu+ cascade dissociative
emission are obtained. Predissociation of the d3Πu state
produces H atoms with an average Ek of 2.3±0.4 eV/atom, while the
Ekdistribution of the d3Πu-a3Σg+-b3Σu+
channel is similar to that of the
X1Σg+-a3Σg+-b3Σu+ channel and
produces H(1s) atoms with an average Ek of 1.15±0.05eV/atom. On
average, each H2 excited to the d3Πu state in an
H2-dominated atmosphere deposits 3.3±0.4eV into the atmosphere,
while each H2directly excited to the a3Σg+ state gives
2.2-2.3eV to the atmosphere. The spectral distribution of the
calculated a3Σg+-b3Σu+ continuum emission due
to the X1Σg+-d3Πu excitation is significantly
different from that of direct a3Σg+ excitation.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 30 5814 Adiabatic excitation energies and vibrational overlap
integrals of the
X1Σg+(vm,Jm)-d3Πu(vn,Jn)
transition
table5.dat 50 16075 Adiabatic energies, transition frequencies, transition
probabilities, and Franck-Condon factors of the
H2 d3Πu-a3Σ_g+ band system
--------------------------------------------------------------------------------
See also:
J/A+A/550/A12 : NGC253 near-infrared H2 emission (Rosenberg+, 2013)
J/MNRAS/418/1994 : GM 2-4 H2 emission-line objects (Khanzadyan+, 2011)
J/ApJ/711/1236 : Equivalent width of H2 from FUSE (Jensen+, 2010)
J/A+A/474/941 : Spectroscopy of H2 towards HH91A (Gredel+, 2007)
J/ApJS/165/256 : Fluorescent H2 emission from T Tauri stars (Herczeg+, 2006)
J/A+AS/141/297 : H2 total transition probability (Abgrall+, 2000)
http://www.nist.gov/pml/data/hdel : NIST energy levels of Hydrogen & Deuterium
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- vn [0/20] Upper vibrational quantum number
4- 5 I2 --- Jn [1/24] Upper rotational quantum number
7 I1 --- vm [0/1] Lower vibrational quantum number
9- 10 I2 --- Jm [0/20] Lower rotational quantum number
12- 19 F8.1 cm-1 Emn [96234/133610] Adiabatic excitation energy
21- 30 E10.3 --- <Int> [-0.6/0.7] Vibrational overlap integral (1)
--------------------------------------------------------------------------------
Note (1): Of the <vn,Jn> and <vm,Jm> levels. The rotationally dependent
Franck-Condon factor is obtained by a squaring this value. Only the
quantities for the vm=0 & 1 and Jm=0-20 levels with
ΔJ=-4, -3, -2, -1, 0, 1, 2, 3, and 4 are listed.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- v1 [0/20] Upper vibrational quantum number
4- 5 I2 --- J1 [0/21] Upper rotational quantum number
7- 8 I2 --- v0 [0/20] Lower vibrational quantum number
10- 11 I2 --- J0 [0/20] Lower rotational quantum number
13- 21 F9.2 cm-1 Energy [111754.5/133834] Adiabatic energy of
the upper level
23- 30 F8.2 cm-1 Freq [-6620/38533.4] Transition frequency (1)
32- 40 E9.3 s-1 A Transition probability (2)
42- 50 E9.3 --- FCF [0/0.96] Franck-Condon factor (3)
--------------------------------------------------------------------------------
Note (1): The energy difference between the d3Πu and a3Σg+
levels. Thus, when the frequency is positive, (v1,J1) refers to the
d3Πu level while (v0,J0) refers to the a3Σg+
level. When it is negative, (v1,J1) refers to the a3Σg+
level and (v0,J0) refers to the d3Πu level.
Note (2): Positive even when the transition frequency is negative.
Note (3): Note also FCF=|<(v1,J1|v0,J0)>|2.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-May-2016