1. What did DeBoer do at the US Space Force last summer? Gary DeBoer Associate Professor of Chemistry LeTourneau University Longview, TX Oct. 20, 2005

6. Model Reactions of Interest Using GaussianW03 1.Ethene O atom chemistry 2.Propene O atom chemistry 3.Phosphonate O atom chemistry To determine energies of reactions, stability of intermediates and reaction products, and simulate IR spectra of reaction productions to compare with and direct experimental work.

7. 1)Form O* 2) Collide O* with ethylene or propylene 3) Look at vibrationally excited (IR-emitting) products using step-scan, time-resolved Fourier transform infrared emission spectroscopy SO 2 + h  nm   SO + O* O 2  O* + O* O* + C 2 H 4  products( ) products( )  products(  ) + IR General Experimental Methodology

8. Old Experimental Setup SO 2 + h  nm   SO + O*

9. New Experimental Setup O 2  2 O Microwave discharge

10. Intensity (arb. units) Time (  s) Wavenumber (cm -1 ) SO 2 CO C2H4C2H4 HCO CH 2 O Ar/C 2 H 4 /SO 2 = 120/100/10 sccm, 1.4 torr, 8 cm -1 res.

11. Ethene Reactions

12. General Calculation Methodology 1.Molecular Mechanics 2.Semi-empirical 3.Ab initio Hartree Fock (HF) Perturbation methods (MP2,MP4) Configurational Interaction (CI) Density Functional Theory (DFT) Unrestricted B3LYP 6-31+ (d,p) DFT includes correlation interactions, which HF does not, at an affordable cost in computational resources.

13. Ethene Reactions

21. Ethene + O atom Reactions Rxn No. Reactant(s)Product(s)Energy (A.U.) Reactant(s)T.S.Products  E rxn EA forEA rev 1ethene + O atom (triplet) Ketocarbene-153.66725058-153.67471998-153.71366345 -0.04641287-0.007469400.03894347 2ketocarbene (triplet) vinoxy radical and hydrogen atom -153.71366300-153.68059277-153.68662488 0.027038120.033070230.00603211 3ketocarbene (triplet) ethanal-153.71366300-153.66231487-153.72901020 -0.015347200.051348130.06669533 4ketocarbene (triplet) CH2 (triplet) and formaldehyde -153.71366300-153.66800901-153.67004920 0.043613800.045653990.00204019 5ethanal (triplet) methyl radical and formyl radical -153.72901020-153.70240520-153.70762510 0.021385100.026605000.00521990 6oxirane (singlet) ethanal-153.80083190-153.69803503-153.84518880 -0.044356900.102796870.14715377 7ethanal (singlet) ethen-1-ol-153.84518880-153.72748793-153.82520240 0.019986400.117700870.09771447 8ethen-1-ol (singlet) H2O and ethyne -153.82520240-153.69505146-153.77118471 0.054017690.130150940.07613325

22. 1 2 3 4 5 6 7 8

23. 1 2 3 4 5 6 7 8 9

24. Ethene Results Agreement with literature –Quantitative –Qualitative ISC of ketocarbene from triplet to singlet produces a structure that optimizes to the aldehyde

26. Propene Reactions

29. Rxn No. Reactant(s)Product(s)Energy (A.U.) ReactantsT.S.Products  E rxn EA forEA rev 9propene + O atom (triplet) ketocarbene-192.99040400-192.99980578-193.03759993 -0.04719593-0.009401780.03779415 10ketocarbene (triplet) propanal-193.0374576-192.98745247-193.04704170 -0.00958410.050005130.05958923 11ketocarbene (triplet) ethyl carbene and formaldehyde -193.0374576-192.99912077-192.99924413 0.038213470.038336830.00012336 12ketocarbene (triplet) propyl vinoxy radical and H atom -193.0375999-193.00770234-193.01419908 0.023400850.029897590.00649674 131-propanal (triplet) methyl and vinoxy radicals -193.0470417-192.99338753-193.03368669 0.013355010.053654170.04029916 141-propanal (triplet) ethyl and formyl radicals -193.0470417-193.02678239-193.03039397 0.016647730.020259310.00361158 15propylene oxide (singlet) ethene and formaldehyde -193.12640490-193.00232952-193.34111700 -0.214712100.124075380.33878748 16propylene oxide (singlet) 1-propanal (singlet) -193.12640490-193.03370436-193.16201570 -0.035610800.092700540.12831134 171-propanal (singlet) ethene and formaldehyde -193.16201570-193.03617776-193.11117000 0.050845700.125837940.07499224 181-propanal (singlet) propen-1-ol-193.1620157-193.05270477-193.14660010 0.015415600.109310930.09389533 19propen-1-ol (singlet) propyne and H2O -193.1466001-193.01678796-193.10123850 0.045361600.129812140.08445054

30. 9 10 11 12 13 14 15 16 17 18 19 Intersystem Crossing

31. Propene Results Agreement with literature –Less to go on here ISC of ketocarbene from triplet to singlet produces a structure that may lead to the propanal, or possibly to formaldehyde and ethene.

32. So, why is the Space Force interested?

33. Space Situational Awareness

34. Conclusions Gaussian can calculate energy pathways The unrestricted DFT B3LYP 6-31+(d,p) seems to compare well with some experimental results for ethene. TS results are the most challenging. If it works for ethene, it may be applicable to propene, butene, etcene. The results are for systems with no rotational or vibrational energies-can’t calculate hot spectra. The work is easily portable and we can continue the alkene work at LeTourneau.

35. Future Work? Look more at non isodesmic singlet dissociations –Bit more complicated Larger hydrocarbons, butenes –Number of reactions increases –Calculation time increases with larger molecules US Space Force Space Scholars Program