1. Vibrational and Hyperfine Coupling Effects in (HI) 2 S. P. Belov, F. Willaert, B. A. McElmurry, R. R. Lucchese, J. W. Bevan, L. H. Coudert, and J. T. Hougen

2. Overview Interesting from the chemical point of view Analysis of the microwave data recorded at Texas A&M University Interesting from the physical point of view Hyperfine-rotational-vibrational energy levels

3. The hydrogen halide dimers family (HF) 2 (HCl) 2 (HBr) 2 (HI) 2 Dyke, Howard, and Klemperer, J. Chem. Phys. 56, 2442 (1972) Schuder, Lovejoy, and Nesbitt, J. Chem. Phys. 99, 4346 (1993) Chen, Hight Walker, Novick, and Tao, J. Chem. Phys. 106, 10386 (1997) Castillo-Chara, McIntosh, Wang, Lucchese, and Bevan, J. Chem. Phys. 120, 10426 (2004) Present investigation.

4. The interconversion geared-type motion

5. The potential energy function V(  ) (HF) 2 (HCl) 2 (HBr) 2 (HI) 2  E  0.6615.515.017.1 Dyke, Howard, and Klemperer, J. Chem. Phys. 56, 2442 (1972) Schuder, Lovejoy, Lascola, and Nesbitt, J. Chem. Phys. 99, 4346 (1993) Castillo-Chara, McIntosh, Wang, Lucchese, and Bevan, J. Chem. Phys. 120, 10426 (2004)

6. The very large quadrupole moment The iodine nucleus has a very large quadrupole moment.

7. The very large quadrupole coupling The HI molecule displays a very large electric quadrupole coupling constant. 1 1. Chance, Varberg, Park, and Zink, J. Mol. Spec. 162, 120 (1993)

8. Accounting for the large quadrupole coupling  J  matrix elements I 2 Hanes, Lapierre, Bunker, and Shotton, J. Mol. Spec. 39, 506 (1971)  v  matrix elements

9. Hyperfine coupling Hamiltonian

10. Hyperfine coupling matrix elements (CH 2 NH 2 ) 2 Merke and Coudert, J. Mol. Spec. 237, 174 (2006)

11. The measurements Paper WJ02, McElmurry, Wang, Lucchese, Bevan, and Belov, Columbus 2006

12. The R(0), v  transition RMS  18 kHzWithout  v  1 matrix elements, RMS  36 kHz

13. Spectroscopic constants

14. The R(3), v  transition Spin-rotation: I·J Quadrupole distortion:  J 2, Q:V}