1. Global fit analysis including 9 + 4  4 hot band of ethane: Evidence of interaction with the 12 fundamental J.R. Cooper and N. Moazzen-Ahmadi University of Calgary

2. Ethane is often used as benchmark molecules to investigate torsion around C-C bond. Its significance lies in the fact that much more complex molecules that occur in biological environments undergo similar internal motions and insight obtained in mechanisms responsible for internal rotation in ethane will be useful in understanding the corresponding effects occurring in complex biological systems. N6-methyl adenine: modification of DNA structure by the addition of methyl groups (black) affects protein:DNA interactions and so can control gene expression.Importance

3. Importance The C-H stretching vibrations are used to monitor ethane in the Earth's atmosphere. The lowest frequency vibrational fundamental (12 µ m) has been used to determine the abundance of ethane in the atmospheres of Jupiter, Saturn, Titan, Neptune and comets.

4. Importance of hindered internal rotation Hindered internal rotation is a very low-frequency vibrational mode and strongly anharmonic. Ground vibrational state Excited vibrational state Bath statesState mixing IVR Torsional sublevels

5. Torsion N. Moazzen-Ahmadi et al., Journal of molecular spectroscopy (2001).

6. v 4 = 1 v 4 = 0 V 9 = 1 Methyl rock gs The 9 fundamental

7. High overtone band v 4 = 1 v 4 = 0 V 9 = 1 gs

8. V 9 = 1 gs Methyl rock Two-band analysis N. Moazzen-Ahmadi et al., Journal of chemical physics (1999).

9. 0.4 Torr, 2 m, -140 C, 0.0024 cm -1

10. Ethane on Saturn in emission F.M. Flasar et al., Science (2005).

11. Ethane on Titan F.M. Flasar et al., Science (2005).

12. 0 1 2 3 4 gsgs 0 1 V 9 = 1 0 1 V 3 3 C-C stretch

13. 0 1 2 3 4 gsgs N. Moazzen-Ahmadi Journal of molecular spectroscopy (2001). 0 1 V 9 = 1 0 1 V 3 = 1 Three-band analysis

14. C-C stretching fundamental CH3CH3 A. Al-Kahtani et al. JCP 98, 101 (1993).

15. 0 1 2 3 4 gsgs N. Moazzen-Ahmadi Journal of molecular spectroscopy (2001). 0 1 V 9 = 1 0 1 V 3 = 1 9 + 4  4 band 9 + 4  4 band

17. High temperature spectrum (T = 295 K) gs 0 1 2 3 9 = 1 0 1 2

18. Low temperature spectrum (T = 128 K) gs 0 1 2 3 9 = 1 0 1 2

19. No data for 12 !

20. 12  9 band 12  9 band

21. Energy pathways in ethane