1. INFRARED SPECTRUM OF MATRIX-ISOLATED METHYLHYDROXYCARBENE INFRARED SPECTRUM OF MATRIX-ISOLATED METHYLHYDROXYCARBENE C. A. BAUMANN Department of Chemistry The University of Scranton

2. Methylhydroxycarbene transcis triplet

3. Gas phase photochemistry of biacetyl

4.  < 450 nm Gas phase photochemistry of biacetyl

5. Difference spectra- 405 nm irradiation

6. Computational Details Gaussian 03W Gaussian 03W UB3LYP, UMP2, UMPW1K UB3LYP, UMP2, UMPW1K 6-311++G(2d,p) 6-311++G(2d,p) Scale factors: 0.963, 0.961, 0.943 Scale factors: 0.963, 0.961, 0.943 a Gaussian 03, Revision C.02, Frisch, M. J. et al. Gaussian, Inc., Wallingford CT, 2004; Becke, A. D. J. Chem. Phys. 1993, 98, 5648; Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785; Møller, C.; Plesset, M. S. Phys. Rev. 1934, 46, 618; Lynch, B. J.; Fast, P. L.; Harris, M.; Truhlar, D. G. J. Phys. Chem. A 2000, 104, 4811-4815.

7. trans-CH 3 COH*CH 2 CO cis-CH 3 COH*CH 2 CO triplet-CH 3 COH*CH 2 CO

8. cis-CH 3 COH*CH 2 CO

9. CH 3 COH*CH 2 CO Vibrations

10. CD 3 COD*CD 2 CO Vibrations

11. Intramolecular Hydrogen Transfer

12. Acetyl-Acetyl Hydrogen Transfer

13. Apparent efficiencies for the production of ketene and MCA.  (nm) matrix CH 2 COCD 2 CO H/DMCAMCA-d 6 H/D N2N2 3(2)×10 -3 1.4(5)×10 -4 213 (2) ×10 -3 5(3)×10 -4 6 O2O2 4(2) ×10 -3 4(2) ×10 -4 116(3) ×10 -3 2.5(5) ×10 -3 2 405 Ar2(2) ×10 -3 4(1) ×10 -5 542(2) ×10 -3 1.7(3) ×10 -4 79 Kr1.2(7)×10 -3 7(3) ×10 -6 1762(1)×10 -3 2(1)×10 -5 82 Xe9(5)×10 -4 3(3) ×10 -6 3001.2(7) ×10 -3 6(6) ×10 -6 195 O2O2 4(2) ×10 -4 436 N2N2 3(2) ×10 -3 8(3) ×10 -4 Ar4(4) ×10 -4 2(2) ×10 -5 256(6)×10 -5 7(7)×10 -5 0.8 254 N2N2 3(2) ×10 -3 < 10 -5 Ar0.02(3)0.006(6)2< 10 -5

14. Concentration Dependence

16. Pulsed vs. Continuous Irradiation 405 nm337 nm

17. Pulsed plus Continuous Irradiation

18. Triplet-Triplet Absorption

22. Conclusions cis conformation, complexed with ketene cis conformation, complexed with ketene H/D isotope effect H/D isotope effect Acetyl-acetyl H abstraction Acetyl-acetyl H abstraction Triplet-triplet absorption-T 4 Triplet-triplet absorption-T 4

23. Acknowledgments Petroleum Research Fund of the American Chemical Society Petroleum Research Fund of the American Chemical Society National Science Foundation National Science Foundation Research Committee Research Committee Faculty Development Board Faculty Development Board