1. 71 st International Symposium on Molecular Spectroscopy
Photodissociation dynamics of N contaning heterocyclic molecules; pyridine and isoxazole studied using chirped pulse uniform flow spectroscopy
This study had been started in our lab back in Wayne state university and continued at university of missouri.
Nuwandi M. Ariyasingha
University of Missouri Columbia

2. Pyridine Isoxazole Agrochemical and pharmacological applications
71 st International Symposium on Molecular Spectroscopy
Pyridine
Isoxazole
Agrochemical and pharmacological applications
N containing building blocks of PAH
Volatile
Vapor pressure ~ 18 mmHg and ~ 97 mmHg for pyridine and isoxazole respectively
Direct photolysis
Adverse health effects

3. C5NH5→ C5NH4 + H ; direct dissociation (10%) C5NH5→ C4H4 + HCN
Previous studies
71 st International Symposium on Molecular Spectroscopy
A multi-mass ion imaging study done by Chi-Kung Ni , Y T Lee and Alex Mebel in 2005
C5NH5→ C5NH4 + H ; direct dissociation (10%)
C5NH5→ C4H4 + HCN
C5NH5 → C3H3 + C2NH2
C5NH5 → C2H4 + C3NH
C5NH5 → C4NH2 + CH3 (14%)
C5NH5 → C2H C3NH3
ring opening channels
Lin. M.F.; Dyakov. Y.A.; Tseng. C.M.; Mebel. A.M.; Lin. S.H.; Lee. Y.T.; Ni. C.K. J. Chem. Phys. 2005, 123,

4. Instrumentation and Method
71 st International Symposium on Molecular Spectroscopy
Instrumentation and Method
Chirped Pulsed FTMW
Pulsed Uniform Supersonic Flow system
High density flows (1016 cm-3)
Uniform, collimated flows
Constant pressure
Temperature (22K/26K)
CPUF

5. Chirped Pulse in Uniform Flow (CPUF)
71 st International Symposium on Molecular Spectroscopy
Chirped Pulse in Uniform Flow (CPUF)

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Results 1.

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t = 10 µs
t = 20 µs
t = 30 µs
t = 40 µs
t = 50 µs
t = 60 µs
t = 70 µs
t = 80 µs
t = 90 µs
t = 100 µs
t = 120 µs
t = 110 µs
Frequency / GHz
HCN J= 1-0 2.

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MITC frames 1 to 12 laser on 100 k aquisitions

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12. Results By Alexander Mebel o: m:p = 36:5:4 .0012 11.8 1.8
HC3N at GHz
HC3N at GHz
Each spectrum is averaged for 125 k
1.8
By Alexander Mebel

13. Calculated Branching using CPUF HCN : HNC 8 : 1
71 st International Symposium on Molecular Spectroscopy
However,
Calculated Branching using CPUF
HCN : HNC : 1
In theory
HCN : HNC :

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Estimated branching (%)
RRKM
MESS calculations
HCN + C4H4 11 21
HNC + C4H4 
1E-04
8E-05
C2H2 + C2H3CN
6E-03
2E-03
C2H4 + HCCCN 2
1E-01
o-C5H4N + H  36 15
m-C5H4N + H 5
p-C5H4N + H  4
CH3 + HC3HCN 35
i1  3
i17 31
i18 
5E-01
i21
i26 
7E-02
By Alexander Mebel

16. Results Isomerization !! By Alexander Mebel .0012 11.8
HC3N at GHz
HC3N at GHz
Each spectrum is averaged for 125 k
By Alexander Mebel

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Discussion
HCN can be produced hot.
Excess energy ~ 82 kcal/mol distributed between translational and internal energies of fragments.
Hot HCN isomerizes to HNC Hot distribution branching ratios;
Well  E, kcal/mol       HCN     HNC HCN       60.              0.52     0.47 HCN      50.               0.60     0.39 HCN      40.               0.65     0.34 HCN      39.               0.66     0.33 HCN      38.               0.66     0.33 HCN      37.               0.66     0.33 HCN      36.               0.67     0.32 HCN      35.               0.67     0.32 HCN      34.               0.68     0.31 HCN      33.               0.74     0.25 HCN      32.               0.88     0.11 HCN      31.               0.99   0.006

18. Isoxazole photodissociation at 248 nm: preliminary results
71 st International Symposium on Molecular Spectroscopy
Isoxazole photodissociation at 248 nm: preliminary results

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Acknowledgement
Prof. Arthur Suits (MIZZOU)
Prof. Alexander Mebel (FIU)
Dr. Baptiste Joalland (RENNES)
C-PUF Team
Former members
Dr. Lindsay Zack
Dr. Chamara Abeysekara
Suits Group Members
DOE & NSF

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Thank You

22. fragment transnational energy distributions of the reactions C5NH5→C3NH
+C2H4 and C5NH5→C4H4+HCN show that the maximum
transnational energies reach the maximum available energies
of these reactions. Since the maximum transnational energy
corresponds to the products produced in the ground electronic
state and the ground states of these closed-shell fragments
only correlate to the ground state of the parent molecule,
the dissociation must occur in the ground electronic state