1. 71 st International Symposium on Molecular Spectroscopy
Study of K- dependent reaction rates of the Cl+ propyne reaction using chirped pulse uniform flow spectroscopy
Looked at reaction rates vary with different rotation, vibrations of molecules
Nuwandi M. Ariyasingha
University of Missouri

2. 71 st International Symposium on Molecular Spectroscopy
Rotational mode specificity in reactions a lively field
The electrophillic addition reaction is fast and barrierless
Cl + CH3CCH X1A1 (J=3, K)
CH3CClCH
20 K
Emthane isto… early / late brrr
barrierless
Farrell, John T., and Craig A. Taatjes. "Infrared frequency-modulation probing of Cl+ C3H4 (allene, propyne) reactions: kinetics of HCl production from 292 to 850 K." The Journal of Physical Chemistry A (1998):

3. 71 st International Symposium on Molecular Spectroscopy
CH3CCH
Prolate symmetric top (Ia < Ib = Ic)
A good probe for kinetic temperature measurements
Closely spaced rotational lines – belong to states with different K values – energy varying with K
Barrierless reaction, specifically the electrophilic addition of Cl atoms to propyne.

4. Study of the reaction decay rates using CPUF
71 st International Symposium on Molecular Spectroscopy
Study of the reaction decay rates using CPUF
Chirped Pulsed FTMW
Pulsed Uniform Supersonic Flow system

5. 71 st International Symposium on Molecular Spectroscopy
K-dependence of electrophilic addition kinetics at low temperature
Preliminary Results
Cl + CH3CCH (J = 3, K)
CH3CCH (4-3)
Propyne decay rate with K components for given J value.
Frequency (GHz)

6. 71 st International Symposium on Molecular Spectroscopy
K-dependence of chemical reaction rates
Cl + CH3CCH (J=3, K=1)
Time (µs)
CH3CCH (4-3)
Frequency (GHz)

7. 71 st International Symposium on Molecular Spectroscopy
K-dependence of chemical reaction rates
E (cm-1) 1 2 3 4 5 6 7
K=0
K=1
K=2 4
K=0
3.42 cm-1
8.43 cm-1
23.44 cm-1
48.46 cm-1
k=3.5(9)
k=5.5(1.3)
k=2.5(5)
k=1.7(7) 3
20 K 15 cm-1
Signal (arb)
K=1 2
K=2 1
K=3
Time (μs)

8. How does rotation affect reactivity?
71 st International Symposium on Molecular Spectroscopy
How does rotation affect reactivity?

9. Future studies 71 st International Symposium on Molecular Spectroscopy
Reaction kinetics
Bimolecular chemistry
Photochemistry

10. Acknowledgement Prof. Arthur Suits (MIZZOU) Dr. James O. P. Thompson
Dr. Bernadette Brodreick
Suits Group Members
DOE & NSF

11. Thank You

12. 71 st International Symposium on Molecular Spectroscopy
Mixing levels !!!
C3V different symmetry in the nuclei do not combine with one another A <#> E : including collisions