1. CONCENTRATION, MATRIX AND WAVELENGTH DEPENDENCE IN THE PHOTOLYSIS EFFICIENCY OF MATRIX-ISOLATED BIACETYL CONCENTRATION, MATRIX AND WAVELENGTH DEPENDENCE IN THE PHOTOLYSIS EFFICIENCY OF MATRIX-ISOLATED BIACETYL C. A. BAUMANN Department of Chemistry The University of Scranton

2. Triplet-Triplet Absorption

14. products

15. Experimental Details Ar, Kr, Xe, N 2, O 2 (R:M 1:300, 1000, 2000) Ar, Kr, Xe, N 2, O 2 (R:M 1:300, 1000, 2000) irradiation after deposition irradiation after deposition (Hg lamp: 450, 436, 405, 338 nm) (Hg lamp: 450, 436, 405, 338 nm) apparent quantum efficiency  apparent quantum efficiency   vs. time: extrapolated to t=0  vs. time: extrapolated to t=0

16. Computational Details Gaussian 03W Gaussian 03W UB3LYP UB3LYP 6-311++G(2d,p) 6-311++G(2d,p) Scale factor: 0.963 Scale factor: 0.963 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;

17. Horowitz, A.; Meller, R.; Moortgat, G. K. J. Photochem. Photobiol. A 2001, 146, 19. Apparent Quantum Efficiency from DFT Polo, S. R.; Wilson, M. K. J. Chem. Phys. 1955, 23, 2376.

18. Two-parameter fit Probability of isolation Cradock, S.; Hinchcliffe, A.J. Matrix Isolation. A Technique for the Study of Reactive Inorganic Species; Cambridge University Press: Cambridge, 1975, p. 19. Clemitshaw, K. C.; Sodeau, J.R. J. Phys. Chem. 1988, 92, 5491.

26. Limiting efficiencies for the 405 nm production of ketene and GBL. (nm) matrix CH 2 COCD 2 CO H/DGBLCH 2 CO/GBL N2N2 1.4(7)×10 -2 1.0(5)×10 -3 141.4(7) ×10 -2 1 O2O2 1.1(5) ×10 -2 4(2) ×10 -3 31.5(8) ×10 -2 0.7 00 Ar1.4(7) ×10 -3 2(1) ×10 -4 75(2) ×10 -3 0.3 Kr1.4(7)×10 -3 4(2) ×10 -5 282(1)×10 -3 0.7 Xe3(2)×10 -4 2(1) ×10 -3 0.2  N2N2 2(1) ×10 -3 6(3) ×10 -5 33 3(1) ×10 -3 0.7 O2O2 8(4) ×10 -4 4(2) ×10 -4 2 1.1(6) ×10 -3 0.7 Ar3(2) ×10 -5 1.0(5) ×10 -5 31.3(6)×10 -4 0.2 Kr5(2) ×10 -4 4(2) ×10 -5 12 7(4)×10 -4 0.7 Xe6(3) ×10 -5 1.0(5)×10 -4 0.6

27. Conclusions cis CH 3 COH*CH 2 CO and  -butyrolactone cis CH 3 COH*CH 2 CO and  -butyrolactone H/D isotope effect H/D isotope effect Concentration effect at 405 nm:  0 and   Concentration effect at 405 nm:  0 and   Matrix effects Matrix effects More complicated kinetics at 436 and 450 nm More complicated kinetics at 436 and 450 nm

28. 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