1. Yu-Shu Lin, Cheng-Chung Chen, and Bor-Chen Chang Department of Chemistry National Central University Chung-Li 32001, Taiwan ~ ~ Electronic Spectroscopy of the GeCl 2 A-X Transition

2. MX 2 (M= C, Ge, X= Cl, Br) X1A1X1A1 ~ C X X C X X C X X Ge X X X X X X A1B1A1B1 ~ a3B1a3B1 ~ Ultraviolet Wavelengths Visible Wavelengths

3. Karolczak et al., J. Chem. Phys. 98, 60 (1993). LIF Excitation Spectrum of GeCl 2 Congested Band? Mok et al., ChemPhysChem 6, 719 (2005). Assignments of Hot Bands?

4. Dye Laser Nd:YAG Laser HV Power Supply Circuit Valve Controller Delay Generator Experimental Setup PMT LIF Excitation Monochromator ICCD Dispersed Fluorescence SHG ICCD Controller GeCl 4 /He Delay Generator

5. LIF Excitation Spectrum of the GeCl 2 A-X Transition ~

6. Peak Spacings ≈ 160 cm -1 FWHM= 23 cm -1 FWHM= 16 cm -1

7. Dispersed Fluorescence Spectra of Pumping Various Bands

10. GeCl 2 70 Ge 21.23% 72 Ge 27.66% 73 Ge 7.73% 74 Ge 35.94% 76 Ge 7.44% 35 Cl 75.77% 37 Cl 24.23%Isotopes GeCl 2 has 15 isotopomers! The major observed progression is emission to the ground state bending vibrational levels. Cl isotope structure is possibly resolvable. Bending frequency: Ge 35 Cl 2 > Ge 35 Cl 37 Cl > Ge 37 Cl 2

13. Vibrational Parameters (cm -1 ) for the GeCl 2 X State a ~ a One standard deviation in parentheses. b Karolczak et al., J. Chem. Phys. 98, 60 (1993). c Mok et al., ChemPhysChem 6, 719 (2005). d Miller et al., J. Mol. Struct. 77, 65 (1981). Ge 35 Cl 2 Ge 35 Cl 37 Cl Ge 37 Cl 2 LIF b Theoretical c 409.0(8) 391.2(7) b 409 c 159.29(5)158.19(10)154.36(3) 160.0(1) b 160 c 352(5) 372 d 389 c -0.079(1)-0.087(4) -0.7(6) b -0.78(3) 2.22.12.4 No. of Levels 84201811

14. LIF Excitation Spectrum of the GeCl 2 A-X Transition ~

16. Blue Shift 160 cm -1 Pump at

17. 31000312503150031750320003225032500 Wavenumber (cm ) B C D A LIF Excitation Spectrum of the GeCl 2 A-X Transition ~

19. A B C D +: He Emission

20. Nature of The Congested Band GeCl: X X Discharge background Predissociation producing GeCl+Cl? Multiphoton Process? (GeCl 2 ) n van der Waals clusters?

21. +: He Emission

22. Summary Determined the detailed vibrational structure of the ground singlet electronic state. Clarified the hot band assignments. Provided more experimental data for unraveling the nature of the congested diffuse structure. J. Chem. Phys. 124, 224322 (2006).

23. AcknowledgmentsSupports: National Science Council, Taiwan National Central University Thank you for your attention ! Yu-Shu LinCheng-Chung Chen