June 22-26, th International Symposium on Molecular Spectroscopy The Pure Rotational Spectrum of TiS (X 3 r ) in all Three Spin Components Robin L. Pulliam and Lucy M. Ziurys University of Arizona, Department of Chemistry, Department of Astronomy, Steward Observatory, Arizona Radio Observatory, Tucson, AZ June 22-26, th International Symposium on Molecular Spectroscopy Introduction ScTiVCrMnFeCoNiCuZn F 1+1+4r4r 5r5r 6+6+7+7+6i6i 3i3i 2i2i 1+1+2+2+ Cl 1+1+4r4r 5r5r 6+6+7+7+6i6i 3i3i 2i2i 1+1+2+2+ O 2+2+33 4-4-55 6+6+55 44 3-3-22 1+1+ S 2+2+33 4-4-55 6+6+55 44 3-3-22 1+1+ Previous optical work Microwave and millimeter studies completed Ziurys Lab 3d transition metals June 22-26, th International Symposium on Molecular Spectroscopy Titanium in the ISM TiO and TiH have been identified in the spectra of cool M-types stars 1,2 Titanium carbide has been observed in meteorites 3, indicating its presence in the interstellar medium The presence of titanium carbide nanocrystals is also suspected in the circumstellar gas of post-AGB phase stars 4 [1] R. E. S. Clegg, D. L. Lambert, & R. A. Bell, ApJ, 234, 188 (1979); [2] R. Yerle, A&A,73, 346 (1979); [3] T. J. Bernatowicz, S. Amari, E.K. Zinner, and R.S. Lewis, ApJ Lett., 373, L73 (1991); [4] G. Von Helden et al., Science, 288, 313 (2000); June 22-26, th International Symposium on Molecular Spectroscopy Near-Infrared Laser Spectroscopy of TiS Q. Ran et al, J. Mol. Spec. 198, 175 (1999) Cheung et al., J. Mol. Spec. 203, 96 (2000) June 22-26, th International Symposium on Molecular Spectroscopy Submillimeter Spectroscopy Radiation Source: Phase- locked Gunn oscillators and Schottky diode multipliers ( GHz) Gaussian beam optics utilized to minimize radiation loss Reaction Chamber: Double walled, steel cell which contains a Broida-type oven Detector: InSb bolometer Radiation is modulated at 25kHz and detected at 2f June 22-26, th International Symposium on Molecular Spectroscopy Molecular Synthesis Melt titanium in Broida type oven m.p. = 1668 C (3034 F) Titanium rod, 1 length by diameter (ESPI, 99.7%) Hydrogen sulfide gas Between 3-5 mtorr for best production June 22-26, th International Symposium on Molecular Spectroscopy Difficulties with Titanium Baskets 9.8 V, 70 A ~ 10.5 V, 75 A Posts hastelloy vs molybdenum Buckets Alumina vs. Boron nitride Titanium splashes everywhere Slow heating process heavy insulation w/ alumina pieces and zirconia felt m.p. = 1668 C (3034 F) Purity of Titanium - Titanium rod, 1 length by diameter (ESPI, 99.7%) June 22-26, th International Symposium on Molecular Spectroscopy June 22-26, th International Symposium on Molecular Spectroscopy June 22-26, th International Symposium on Molecular Spectroscopy Hunds case(a) June 22-26, th International Symposium on Molecular Spectroscopy 48 TiS, v=0 48 TiS, v=1 46 TiS, v=0 J+1J obs a obs - calc a obs a obs - calc a obs a obs - calc a 26 a) in MHz June 22-26, th International Symposium on Molecular Spectroscopy Hunds case(a) Hamiltonian eff = rot + so + ss 48 TiS (this work) 46 TiS (this work) 48 TiS (optical) B0B (16) (49) (27) D0D (79) (25) * A (980) (2900) * ADAD * (90)* (27)- 33345(42)33480(120)132000(10000) rms BeBe ee DeDe ee 1.409x10 -5 r e () e (cm -1 ) 562 e e (cm -1 ) 1.92 D E (eV)5.09 = B (J-S) 2 D (J-S) 4 + H (J-S) 6 + A (LS) + A D {LS, (J- S) 2 } + 2 / 3 (3S z 2 -S 2 ) 10 transitions measured for 48 TiS, v=0 9 transitions each measured for 46 TiS, v=0 and 48 TiS, v=1 June 22-26, th International Symposium on Molecular Spectroscopy Bonding Trends Sc-Ti-V steady decrease because of increasing charge on metal Similar trends between oxides and sulfides with some subtle differences Oxygen more electronegative 3p orbital of S is ~4 eV higher in energy than 2p of O Comparison of experimental values with theoretical calculations Jensen et al DFT calculation using B3LYP, BP86, PBE0, PBE, BLYP r e (experimental) = r e (theoretical) = 2.08 June 22-26, th International Symposium on Molecular Spectroscopy Summary Verified the 3 r ground state Established molecular parameters for three all spin components Our results agree well with previous optical work completed Good agreement between theoretical and experimental bond lengths of the 3d transition metal sulfides and oxides Future Directions Continue with titanium molecules in the laboratory (TiSH ( 4 A) and TiOH ( 4 A)) Conduct a search for TiS around evolved stars using radio observations June 22-26, th International Symposium on Molecular Spectroscopy Acknowledgements Lucy Ziurys Rest of Ziurys Group DeWayne HalfenEmily Tenenbaum Lindsay ZackMing Sun Gilles AdandeJessica Dodd Matthew BucchinoJie Min Brent Harris NSF and NASA - Funding