1. Thomas J. Preston, Michael A. Shaloski, and F. Fleming Crim Infrared Transient Absorption Spectroscopy of Bromoform Isomerization

2. Isomerization of Halomethanes Preston et al. J. Chem. Phys. 2011, 135, 114503

3. Potential Energy Surface for Isomerization Preston et al. J. Chem. Phys. 2011, 135, 114503

4. Bromoform Isomerization Carrier et al. J. Phys. Chem. A. 2010, 114, 1548

5. Infrared Probing (Matrix Studies) George et al. J. Chem. Phys. 2011, 135, 124503 Mode Description Transition Frequency in cm -1 CHBr 3 C-H Stretch3051 iso-CHBr 2 -BrC-H Stretch3076

6. Infrared Probing (Time-Resolved) Transition Frequency in cm -1 IR Bleach3027 IR Absorbance3052

7. Infrared Probing (Time-Resolved) Feature τ 1 τ 2 IR Bleach5.3±2.622±7 IR Absorbance9.0±0.698±17 443 nm Absorbance19±1.0124±44

8. Assignments George et al. J. Chem. Phys. 2011, 135, 124503

9. Early Feature Assignment Time-Dependent DFT -M06-2x functional -Sadlej-pVTZ basis set Species / nm  / M -1 cm -1 Br--CHBr 3 3003860 Br--CHBr 3 3691535 CHBr 3 --Br--CHBr 3 3321185 CHBr 3 --Br--CHBr 3 3391355 Chromophore should be dependent on bromoform concentration

10. Dilution Study Repeated 267 pump, 350 – 700 nm probe -Varied concentration from 100% – 2% bromoform -Normalized 1 ns signals -Scaled 2 ps signal by same factor

11. Summary IR Results Photolysis leads to prompt bleach in C-H region of bromoform Absorption feature of iso-bromoform appears with a characteristic time of 9.0 ps Lasts > 1 ns UV/Visible Results 490 feature assigned to isomer 390 feature assigned to Br – CHBr 3 contact pair Electronic structure calc. Dilution experiment

12. Acknowledgements NSF Funding Crim Group Fleming Crim Thomas J. Preston Collaborators Bob McMahon Scott Reid Ned Sibert