Neal Kline Meng Huang and Terry A Miller

  • Slides: 23
Download presentation
 Neal Kline, Meng Huang, and Terry A. Miller Department of Chemistry and Biochemistry

Neal Kline, Meng Huang, and Terry A. Miller Department of Chemistry and Biochemistry The Ohio State University Richard Dawes Department of Chemistry Missouri University of Science and Technology

Introduction Photolyze diiodomethane at 248 nm, one iodine atom dissociates. CH 2 I radical

Introduction Photolyze diiodomethane at 248 nm, one iodine atom dissociates. CH 2 I radical reacts with oxygen to give CH 2 IOO then dissociates I atom to give CH 2 OO. a We observed our spectrum under conditions of 86. 0 torr total pressure (84. 9 torr N 2, 0. 1 torr CH 2 I 2, 1. 0 torr O 2) , which is the same conditions as Y. P. Lee. b a. Oliver Welz et al. , Science, 335 204, 2012; b. Su, Y. ; Huang, Y. ; Witek, H. A. and Lee, Y. P. Science 2013, 340, 174.

Comparison of the Spectra for CH 2 XOO Radicals * 6817 cm-1 * 6799

Comparison of the Spectra for CH 2 XOO Radicals * 6817 cm-1 * 6799 cm-1 * 6908 cm-1

Potential Energy Surface calculated for CH 2 IOO

Potential Energy Surface calculated for CH 2 IOO

Potential Energy Surface on ground state, CH 2 IOO Eigenvalu es(cm-1) ν 12 =

Potential Energy Surface on ground state, CH 2 IOO Eigenvalu es(cm-1) ν 12 = 0 40. 4 ν 12 = 1 120. 1 ν 12 = 2 196. 1 ν 12 = 3 268. 0 ν 12 = 4(G) 334. 7 ν 12 = 4(T) 334. 8

Potential Energy Surface calculated for CH 2 Cl. OO

Potential Energy Surface calculated for CH 2 Cl. OO

Potential Energy Surface calculated for CH 2 Cl. OO Eigenvalu es(cm-1) ν 12 =

Potential Energy Surface calculated for CH 2 Cl. OO Eigenvalu es(cm-1) ν 12 = 0 50. 5 ν 12 = 1 145. 8 ν 12 = 2(G) 235. 6 ν 12 = 2(T) 286. 2 ν 12 = 3(G) 318. 6 ν 12 = 3(T) 345. 4

Franck-Condon Simulation Cartesian coordinate calculation——e. Zspectruma Using the eigenvectors and eigenvalues of the harmonic

Franck-Condon Simulation Cartesian coordinate calculation——e. Zspectruma Using the eigenvectors and eigenvalues of the harmonic analysis in electronic structure calculations, the L-matrix in Cartesian coordinates and the normal mode frequencies, as the input Applying Duschinsky rotation to the excited state normal modes Calculate the overlap between ground and excited wavefunctions Simulate the spectrum at finite temperature a. V. A. Mozhayskiy and A. I. Krylov, ez. Spectrum, http: //iopenshell. usc. edu/downloads

Franck-Condon Simulation Internal coordinate calculation a. b. C. C. Lin and J. D. Swalen,

Franck-Condon Simulation Internal coordinate calculation a. b. C. C. Lin and J. D. Swalen, "Internal rotation and microwave spectroscopy, “ Colbert, D. T. ; Miller, W. H. A Novel Discrete Variable Representaion for Quantum Mechanical Reactive Scattering via the S-matrix Kohn Method. J. Chem. Phys. 1992, 96,

Simulation Result, CH 2 IOO CCSD(T)-F 12 b/ CASSCF(13 e, 12 o) Cartesian Coordinate

Simulation Result, CH 2 IOO CCSD(T)-F 12 b/ CASSCF(13 e, 12 o) Cartesian Coordinate Calculation Internal Coordinate Calculation Frequency(cm-1)

Simulation Result, CH 2 Cl. OO CCSD(T)-F 12 b/ CASSCF(13 e, 12 o) Cartesian

Simulation Result, CH 2 Cl. OO CCSD(T)-F 12 b/ CASSCF(13 e, 12 o) Cartesian Coordinate Calculation Internal Coordinate Calculation

All Mode Simulations The torsional feature is simulated by the Internal coordinate calculation with

All Mode Simulations The torsional feature is simulated by the Internal coordinate calculation with harmonic oscillator assumption The intensities of the fundamentals of other modes are obtained from the Cartesian coordinate calculation. The frequencies of the fundamentals of other modes are fitted to the spectrum, then compare to the electronic structure values. Simulate the torsion feature on top of every fundamentals. Based on the similarity of the origin region and OO stretch region, combination bands of OO stretch with other modes are also assigned

All Mode Simulations, CH 2 IOO

All Mode Simulations, CH 2 IOO

All Mode Simulations, CH 2 IOO

All Mode Simulations, CH 2 IOO

All Mode Simulations, CH 2 Cl. OO

All Mode Simulations, CH 2 Cl. OO

All Mode Simulations, CH 2 Cl. OO

All Mode Simulations, CH 2 Cl. OO

All Mode Simulations, CH 2 Br. OO

All Mode Simulations, CH 2 Br. OO

All Mode Simulations, CH 2 Br. OO

All Mode Simulations, CH 2 Br. OO

Comparison between the experimental and calculations

Comparison between the experimental and calculations

CH 2 Br. OO and CH 2 Cl. OO

CH 2 Br. OO and CH 2 Cl. OO

Conclusions The Franck-Condon factors have been calculated to simulate the spectra of halogenated methyl

Conclusions The Franck-Condon factors have been calculated to simulate the spectra of halogenated methyl peroxy radicals, CH 2 XOO Internal coordinate calculations has been accomplished on CH 2 X torsions, which successfully explain the multi-peak structure around the electronic origin region. Simulations of the spectra show qualitative good agreement with the experiment.

Dr. Terry A. Miller Dr. Neal D. Kline Scott C. Garner Henry Tran Dr.

Dr. Terry A. Miller Dr. Neal D. Kline Scott C. Garner Henry Tran Dr. Richard Dawes

CH 2 X torsion CH 2 IOO(C CSD/CAS) CH 2 Br. OO(DFT) CH 2

CH 2 X torsion CH 2 IOO(C CSD/CAS) CH 2 Br. OO(DFT) CH 2 Cl. OO(C CSD/CAS) XCOO dihedral(degree) 82. 0 86. 7 79. 6 XCOO Torsion Frequency(cm-1) 82. 1 91. 5 103. 9 F Constant(cm-1) 1. 262 1. 427 1. 673 75. 8 74. 3 75. 3 XCOO Torsion Frequency(cm-1) 116. 2 127. 0 147. 0 F Constant(cm-1) 1. 219 1. 362 1. 613 XCOO dihedral(degree)