Interstellar H3+ in Metastable Rotational Levels
Takeshi Oka and Erik Epp
Department of Chemistry and Department of Astronomy and Astrophysics,
The Enrico Fermi Institute, The University of Chicago
the 58th International Symposium on Molecular Spectroscopy
Columbus Ohio, FA06,10:27, June 20, 2003
Δk = 3 Forbidden Rotational Transitions in H3+
Interstellar NH3 Oka, Shimizu, Shimizu, Watson, ApJ 165, L15 (1971)
General Theory Watson, J. Mol. Spectrosc. 40, 536 (1971)
H3+ Pan, Oka, ApJ 305, 518 (1986)
Ab initio H3+ Neale, Miller, Tennyson, ApJ 335, 486 (1988)
μ
Δk = 3 Forbidden Rotational Transitions in H3+
Interstellar NH3 Oka, Shimizu, Shimizu, Watson, ApJ 165, L15 (1971)
Theory Watson, J. Mol. Spectrosc. 40, 536 (1971)
H3+ Pan, Oka, ApJ 305, 518 (1986)
Theory H3+ Neale, Miller, Tennyson, ApJ 335, 486 (1988)
Metastable
27.2 days
20.4 days
15.8 hours7.9 hours
3.8 hours
32
3
4
3ji jiAc
μ
Quasi-metastable
11.4 years
4000 cm-1
2000 cm-1
0
Radiation Collision Reaction
Rigorous Selection Rules Approximate Random
ortho para ΔI = 0 ortho para ΔI = 0 ΔItotal = 0 + - ΔJ = ± 1, 0
A
A
B
B
C
A
D
B
Rate Equations
1' ' ' '2
' '
( ) exp( )2
J K JK JK J KJK JK
J K
g E Ek C
g kT
2
' '' '
' '
' '' '
' '
( )( ) ( )
( ' ') ( )
( ' ') ( )
( ) ( ) ( ) ( )
J K JKJK J K
J K
J K JKJK J K
J K
e XX
dn JKn H f JK
dt
A n J K A n JK
k n J K k n JK
k n e n JK k n X n JK
2( )JK LJK
C k n H
Production
Spontaneous emission 4 10-7 s-
1
Collision n(H2) 100 cm-3 10-7 s-1
Destruction 10-9 s-1
10-17 s-1
10-7 cm3 s-1 10-9 cm3 s-1
' '' '
' ' ' '
exp( )J KJK JK JK J KJKJ K J K
k g E E
k g kT
H3+ + H2 (H5
+)* H3+ + H2
Detailed balance
12345
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4N
orm
aliz
ed P
op
ula
tio
n
n(H2)
Level
Normalized Populations of H3+ Rotational Energy Levels
T 1000 (K), n(e-) 1E-06 (cm-3), n(X) 0.0001 (cm-3)
0.11101001000
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5N
orm
aliz
ed P
op
ula
tio
n
n(H2)
Level
Normalized Populations of H3+ Rotational Energy Levels
T 300 (K), n(e-) 1E-06 (cm-3), n(X) 0.0001 (cm-3)
Normalized Populations of H3+ Rotational Energy Levels for Various H2 densities
T 1000 (K), n(e-) 1E-06 (cm-3), n(X) 0.0001 (cm-3)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Level
Norm
aliz
ed P
opul
atio
n
0.1
1
10
100
1000
Normalized Populations of H3+ Rotational Energy Levels for Various H2 densities
T 300 (K), n(e-) 1E-06 (cm-3), n(X) 0.0001 (cm-3)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Level
No
rmal
ized
Po
pu
lati
on
0.1
1
10
100
1000
Ortho-H3+
Para-H3+
Para-H3+
Para-H3+
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 200 400 600 800 1000 1200
Tsim
Te
x/T
sim
n(H2)1000
n(H2)100
n(H2)10
n(H2)1
Top Related