73 RD International Symposium on Molecular Spectroscopy June

73 RD International Symposium on Molecular Spectroscopy June 18 -22, 2018, Urbana, IL, USA Infrared Emission from UV-Irradiated Mixtures of CH 2 I 2 and O 2 Probed with a Step-Scan FTIR Spectrometer Ting-Yu Chen and Yuan-Pern Lee Dept. Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan

UV-Irradiated of CH 2 I 2 and O 2 to produce CH 2 OO 2 vibrationally excited CH 2 OO Alam et al. , Phys. Chem. Phys. 13, 11002 (2011)

Experimental setup 3 step-scan FTIR spectrometer M 1 M 3 M 2 M 4 x y f=400 mm Excimer Laser • Photolysis of a flowing mixture of CH 2 I 2 (0. 07 Torr), O 2 (8/16 Torr), and Ar (0. 07 Torr) at 248/308 nm.

Results & Discussion 248 nm-8 Torr 308 nm-8 Torr OH H 2 CO CO 2, CO 4

CO PO 2= 8. 0 Torr, laser(248 nm)=360 m. J, 17 Hz, res=0. 31 cm-1, average 6 spectrum. 5

Vibrational distribution of CO 6 Tvib = 6500 ± 700 K 308 nm B 248 nm A < Evib> / k. J mol-1 Channel 248 nm 308 nm A 32 ± 2 B A: B

Observed and simulated spectra of CO 2 308 nm 248 nm C D < Evib> / k. J mol-1 Channel 248 nm 308 nm C 251 ± 9 D 347 ± 12 C: D 54: 46 7

OH PO 2= 8. 0 Torr, laser(248 nm)=360 m. J, 17 Hz, res=0. 51 cm-1, average 6 spectrum. 8

Vibrational distribution of OH 9 308 nm 248 nm < Evib> / k. J mol-1 248 nm 308 nm 29 ± 2

H 2 CO 10 PO 2= 8. 0 Torr, laser(248 nm)=360 m. J, 17 Hz, res=0. 72 cm-1, average 6 spectrum.

Criegee decomposition−OH formation 11 (248 nm) (308 nm) OH t-HCOOH +O 2 Eint(OH) / k. J mol-1 248 nm 308 nm 29 ± 2 (k. J mol-1) Nguyen et al. , J. Chem. Phys. 142, 124312 (2015)

Reaction pathways of CO 12 A B (248 nm) (308 nm) TS 2 TS 1 Eint (CO)/ k. J mol-1 Channel 248 nm 308 nm A 32 ± 2 B A: B +O 2 TS 6 a A TS 6 b TS 5 TS 4 (k. J mol-1) Shaub et al. , Symp. (Int. ) Combust. 18 th , 811 (1981). 30% 70% high v low v B TS 3 Nguyen et al. , J. Chem. Phys. 142, 124312 (2015)

Reaction pathways of CO 2 13 C D (248 nm) (308 nm) TS 2 TS 1 TS 5 TS 6 +O 2 TS 6 a TS 6 b D Eint(CO 2) / k. J mol-1 Channel 248 nm 308 nm C 251 ± 9 D 347 ± 12 C: D 54: 46 TS 5 TS 4 C TS 3 (k. J mol-1) Nguyen et al. , J. Chem. Phys. 142, 124312 (2015)

Conclusion 14 • The internal energies of CO, CO 2, and OH and the branching ratios at 248/308 nm and 8/16 Torr were estimated. • Two channels formation of CO and CO 2 were observed; new assignment for the high-v component of CO. • Even at 16 Torr, still significant amount of internally excited products were produced. This might affect the kinetic measurements. Thank you for

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CH 2 OO decomposition 17 CO vibrational distribution 0. 05 0. 24 0. 17 ± 0. 09 0. 54 ± 0. 12 0. 09 ? 0. 13 ? 0. 31 30% 70% v= 13 0. 47 0. 75 M. S. Alam, M. Camredon, A. R. Rickard, T. Carr, K. P. Wyche, K. E. Hornsby, P. S. Monks , and W. J. Bloss, Phys. Chem. Phys. 13, 11002 (2011). O. Horie, and G. K. Moortgat, Atmos. En. Viron. , 25 A, 1881 (1991) W. M. Shaub, D. S. Y. Hsu, T. L Burks. , and M. C. Lin, Symp. (Int. ) Combust. 18 th , 811 (1981).

CO-308 nm PO 2= 8. 0 Torr, laser(308 nm)=90 m. J, 17 Hz, res=0. 31 cm-1, average 5 spectrum. 18

19 Vibrational level energies of excited ω = 1335. 879 cm CO 2 ω = 667. 204 cm 1 2 C C -1 -1 ω3 = 2361. 674 cm-1 C C J. W. C. Johns, J. Mol. Spec. 1989, 134, 433.

H 2 O 20

HO 2 21

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