68 th International Symposium on Molecular Spectroscopy Time

68 th International Symposium on Molecular Spectroscopy Time Resolved Infrared Emission from Vibrational Excited Acetylene Following Super Energy Transfer Collisions with Hot Hydrogen Jonathan M. Smith Jianqiang Ma*, Michael J. Wilhelm, Matthew Nikow, and Hai. Lung Dai *University of Pennsylvannia

Observation: Time resolved IR Emission • Translationally hot hydrogen o Abundant in photolytic systems (atmosphere) and combustion • Relevant ambient targets o HCCH o DCCD: test model o SO 2 • Infrared emission o Particularly sensitive to energized species • Harmonic scaling of intensity • Anharmonic shift • Intensity primarily through IR harmonic transition dipole • Time resolved o Capture emission of nascent or nearly nascent energized species (10 nsec+ ) o Dynamics Hartland, G. V. , Xie, W. , Dai, H. -L. , Simon, A. , Anderson, M. J. , Rev. Sci. Instr. , 63, 3261 (1992).

Super Energy Transfer • Experimental Observation: o IR emission from Highly vibrationally excited species following interaction with hot hydrogen atom o Nearly 70% of H translational energy appears in internal energy in HCCH and SO 2 o Significant portion of encounters are “Super” • Model: o Collisions sample deep minima on potential surface o Transient chemical complexes facilitate redistribution of energy • Justification: o Strong collision assumption o Earlier observations: Chemical complexes facilitating inelastic collisions, “Tug of War” o Theory: Bowman group

Generation of Translationally Hot hydrogen From: Wight, C. A. ; Leone, S. R. , "Vibrational state distributions and absolute excitation efficiencies for T-V transfer collisions of NO and CO with H atoms produced by excimer laser photolysis". J. Chem. Phys. 1983, 79 (10), 4823 -4829. Ec. m. H+CO (mass =28) vs. HCCH (mass=26)

Energetics: H+HCCH

H* + HCCH H 2 S Photolysis 193 nm: σ=2. 3 x 10 -18 cm 2/molecule H ET=53 kcal/mole 50 m. Torr HCCH 2 Torr Ar

H* + HCCH Toward Fundamental H 2 S Photolysis 193 nm: σ=2. 3 x 10 -18 cm 2/molecule H ET=53 kcal/mole 50 m. Torr HCCH 2 Torr Ar

HCCH emission simulation: Energy “yardstick” Fundamental emission Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

HCCH emission simulation: Energy “yardstick” 7, 000 cm-1 emission Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

HCCH emission simulation: Energy “yardstick” 9, 000 cm-1 emission Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

HCCH emission simulation: Energy “yardstick” 13, 000 cm-1 emission Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

HCCH emission simulation: Energy “yardstick” Observed experimental emission Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

HCCH emission simulation: Energy “yardstick” Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

HCCH emission simulation: Energy “yardstick” Excellent accurate spectroscopic effective Hamiltonian: Robert, S. ; Herman, M. ; Fayt, A. ; Campargue, A. ; Kassi, S. ; Liu, A. ; Wang, L. ; Di Lonardo, G. ; Fusina, L. , "Acetylene, 12 C 2 H 2: new CRDS data and global vibrationrotation analysis up to 8600 cm-1". Mol. Phys. 2008, 106 (21), 2581 - 2605…

H+HCCH H 2 S Photolysis 193 nm: σ=2. 3 x 10 -18 cm 2/molecule H ET=53 kcal/mole 50 m. Torr HCCH 2 Torr Ar

Energy distribution and evolution: HCCH* 193 nm photolysis of H 2 S in C 2 H 2 and Ar

Proposed Model • Substantial highly excited HCCH* • No vinyl emission observed • Short-lived • H+DCCD?

H+DCCD H 2 S Photolysis 193 nm: σ=2. 3 x 10 -18 cm 2/molecule H ET=53 kcal/mole 50 m. Torr DCCD 2 Torr Ar

Proposed Model • Substantial highly excited HCCH* • No vinyl emission observed • Short-lived • H+DCCD yields [DCCH*]/[DCCD*]= ~ 2: 1

Further support… HBr @ 209. 4 nm: 39. 6 kcal/mole 62% T-V QCT snapshot

Bowman Group: H+HCCH PES • global fit of PES • 50 000 energies at RCCSD(T)/aug-cc-p. VTZ Detailed QCT study Han, Y. -C. ; Sharma, A. R. ; Bowman, J. M. , "Quasiclassical trajectory study of fast H-atom collisions with acetylene". J. Chem. Phys. 2012, 136 (21), 214313.

Experiment QCT Mechanistic insights from QCT Find • ~10% Super Energy Transfer • Mechanistic insights • 1. 6 -1. 8 Angtrom 2 cross-section

General? H+SO 2 H*+SO 2 E 59. 0 (kcal/mol) 29. 2 27. 3 19. 5 OH+SO 9. 2 0 H+SO 2 -21. 9 -44. 2 See: Varandas et al. , PCCP, 2005, 7, 2305

SO 2 IR emission o HBr as fast H atom precusor: 59 kcal/mole translational energy with 193 nm HBr + 193 nm H (59 kcal/mole) + Br*/Br SO*/SO 2‡ (ν 1) Emitting species in the 1000 -1500 cm-1 region SO 2‡ (ν 3) H(fast) + SO 2 OH + SO* H(fast) + SO 2 H + SO 2‡ SO 2 + 193 nm SO* + O

Energy distribution and evolution 6000 0 1, 5 3, 5 5, 5 7, 5 9, 5 11, 5 Wavenumber(*1000 cm-1) 13, 5 15, 5 6000 3000 6000 0 0 1, 5 3, 5 5, 5 7, 5 9, 5 11, 5 Wavenumber(*1000 cm-1) 13, 5 15, 5 6000 3000 0 4000 1, 5 3, 5 5, 5 7, 5 9, 5 11, 5 Wavenumber(*1000 cm-1) 13, 5 15, 5 2000 0

Conclusion: SO 2 H + SO 2‡ • Energy transfer cross section σ: 0. 9 ± 0. 1 Å2 • Hard sphere cross section of H+SO 2: 20 Å2 H* + SO 2 HOSO/HSO 2 OH + SO The lifetime of HOSO/HSO 2 intermediates is reported to be as long as picoseconds

Acknowledgements Temple • Hai-Lung Dai • Matt Nikow, Ph. D. [Agilent] • Jianqiang Ma, Ph. D. [Univ. Penn. ] • • Michael Wilhelm, Ph. D. Ben Datko (ug, ‘ 13) Nader Anz (ug, ‘ 12) Mark Fennimore (ug. ‘ 11) Emory University • Joel Bowman • Amit Sharma [Argonne] • Yong-Chang Halian [Dalian Univ. ] Support • • DE-FG 02 -86 ER 134584 DE-FG 02 -97 ER 14782 (JMB) NSF-MRI 1039925: MU 3 C Temple University