1. Nuclear Spin Dependence of the Reaction of H3+ with H2
Kyle N. Crabtree, Lt. Col. Brian A. Tom, USAF,
Carrie A. Kauffman, and Benjamin J. McCall
University of Illinois
23 June 2010

2. Nuclear Spin Effects in Dense Hydrogenic Plasmas
Kyle N. Crabtree, Lt. Col. Brian A. Tom, USAF,
Carrie A. Kauffman, and Benjamin J. McCall
University of Illinois
23 June 2010

3. + H H3+: Why is it important?
Dominant ionic species in hydrogenic plasma
Cornerstone of interstellar gas-phase ion-molecule chemistry

4. Astronomical Spectroscopy of H3+
36685 Å
R(1,1)u
36681 Å
B. J. McCall Ph.D. Thesis, University of Chicago (2001).

5. Temperature Discrepancy
Temperature derived from H3+ in diffuse clouds ≠ cloud kinetic temperature
T (H3+) ~ 30 K
T (kinetic) ~ 70 K
H3+ + H2  H2 + H3+ reaction allows H3+ population to transfer between ortho and para spin configurations

6. Para-H2 Production 15 K >99.9% purity Ferric Oxide catalyst
B. A. Tom, S. Bhasker, Y. Miyamoto, T. Momose, and B. J. McCall Rev. Sci. Inst (2009), 80,

7. Hollow Cathode Cell
T = 110 – 350 K

8. Spectrometer Spectral Range: 2.2-4.8 μm Output Power: 500-700 μW V HV
200 ms
GND
time
InSb

9. Observed Transitions
R(3,0)
R(3,3)l
R(2,1)u
R(2,2)l
R(1,0)
R(1,1)u

10. Normal H2, No Cooling Pulse Shape: R(1,0)
Pulse on
Pulse off
Tkin
Abs.
Frequency

11. Normal H2, No Cooling Temperatures

12. Normal H2, No Cooling Para-H3+ Percentage
t = 300 ms

13. Normal H2, No Cooling Rotational Temperature
Trot ~ 350 K

14. No Cooling, Enriched p-H2 Peak Areas
ortho-H3+
para-H3+
para-H3+

15. No Cooling, Enriched p-H2 Temperatures

16. No Cooling, Enriched p-H2 Temperatures
H3+ + p-H2  H3+ + o-H2
p-H2; J = 0
o-H2; J = 1
ΔE = 170 K

17. No Cooling, Enriched p-H2 Para-H3+ Fractions

18. Liquid Nitrogen Cooling (n-H2) : Pressure Dependence
H3+ + 2H2  H5+ + H2
High Pressure
Low Pressure
T ~ 130 K

19. Liquid Nitrogen Cooling (p-H2): Temperatures

20. Liquid Nitrogen Cooling (p-H2): para-H3+ Fraction

21. Concluding Remarks

22. Acknowledgements
Brett McGuire
(Emory University)
NSF PHY