1. G. Barratt Park and Robert W. Field
Chirped Pulse Fourier Transform Microwave Spectroscopy in Pulsed Uniform Supersonic Flows
Chamara Abeysekera, James M. Oldham, Baptiste Joalland, Kirill Prozument, Lindsay N. Zack, and Arthur G. Suits
Department of Chemistry, Wayne State University
G. Barratt Park and Robert W. Field
Department of Chemistry, Massachusetts Instiute of Technology
Ian R. Sims
Institut de Physique de Rennes, Université de Rennes

2. Reaction Dynamics
Gives a molecular-level understanding of chemical reactivity
How a reaction proceeds
Predict outcomes
Common techniques:
state-selected REMPI
velocity map imaging

3. Reaction Dynamics For larger and more complex systems:
Lack of isomer- and vibrational level-specific information
Unreliable branching ratios
Products not always able to be inferred

4. Chirped Pulse Fourier Transform Microwave Spectroscopy
Isomer and vibrational level specificity
Definitive identification of species
Broadband advantage

5. Instrumentation

6. Spectrometer (“CPUF”)
26 – 40 GHz
60 – 90 GHz

7. Spectrometer

8. CP-FTMW-PUSF as a probe of nascent vibrational distributions
t = 10 ms x5 v
population
0.09 1
0.23 2
0.56 3
0.06 4
Brouard et al. (2004) JCPA, 108, 7965
Twelve sequential chirps plus FIDs are collected with 5 µs intervals. The nascent distribution is obtained initially and the quick relaxation to the v = 0 state is shown
CP-FTMW-PUSF as a probe of nascent vibrational distributions
t = 65 ms

9. C2H3CN HC3N (v, J) + H2
193 nm

10. Conclusions and Future Directions
CPUF can be used to probe photochemistry
Nascent product vibrational distributions can be investigated
Bimolecular reactions next:
Cl + alkenes
Criegee intermediates and QOOH

11. Conclusions and Future Directions
SOCl2 + C3H6
(analysis in progress)

12. Acknowledgements Prof. Arthur G. Suits (WSU)
Prof. Robert W. Field (MIT)
Prof. Ian R. Sims (Rennes)
Suits, Field, and Sims Groups