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June 26, 2009 64 th International Symposium on Molecular Spectroscopy The Pure Rotational Spectrum of ZnS (X 1  + ) Lindsay N. Zack Lucy M. Ziurys Department.

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Presentation on theme: "June 26, 2009 64 th International Symposium on Molecular Spectroscopy The Pure Rotational Spectrum of ZnS (X 1  + ) Lindsay N. Zack Lucy M. Ziurys Department."— Presentation transcript:

1 June 26, th International Symposium on Molecular Spectroscopy The Pure Rotational Spectrum of ZnS (X 1  + ) Lindsay N. Zack Lucy M. Ziurys Department of Chemistry, Department of Astronomy, Steward Observatory, and Arizona Radio Observatory University of Arizona

2 June 26, th International Symposium on Molecular Spectroscopy Previous Work Mass spectrometry –Dissociation energy (Marquart and Berkowitz 1963; de Maria et al. 1965) Spectroscopic measurements –Absorption spectroscopy of ZnS in region (Sen-Gupta 1933) –X-ray emission and luminescence spectroscopy of crystals and nanoparticles (Laihia et al. 1996; Denzler et al. 1998) Theoretical calculations –Different levels of theory with and without relativistic corrections (e.g. Bauschlicher and Langhoff 1986; Peterson et al. 2007) –Similarities between single molecule and bulk properties (Anderson et al. 1987; Bridgeman and Rothery 2000; Chambaud et al. 2008) –r e ~ 2.04 – 2.12 Å

3 June 26, th International Symposium on Molecular Spectroscopy Instrumentation Direct-absorption spectroscopy Phase-locked Gunn oscillators and Schottky diode multipliers ( GHz) Gaussian beam optics Reaction chamber: double-pass, water-cooled steel cell containing a Broida-type oven InSb bolometer detector Radiation is modulated at 25 kHz and detected at 2f

4 June 26, th International Symposium on Molecular Spectroscopy Direct-absorption mm/sub-mm wave spectrometer

5 June 26, th International Symposium on Molecular Spectroscopy Molecular Synthesis Gas-phase synthesis Zinc vapor produced in Broida-type oven –Alumina crucible in tungsten wire basket –m.p. 420  C H 2 S added over top of oven Argon carrier gas d.c. discharge needed (250 mA at 200 V)

6 June 26, th International Symposium on Molecular Spectroscopy 42 GHz (~7B) initially scanned continuosly

7 June 26, th International Symposium on Molecular Spectroscopy 64 Zn : 66 Zn : 67 ZnS: 68 Zn : 70 Zn 49: 28: 4: 19: 0.6% 64 ZnS v = 0 68 ZnS v = 0 66 ZnS v = 1 67 ZnS v = 0 66 ZnS v = 0 64 ZnS v = 1

8 June 26, th International Symposium on Molecular Spectroscopy

9 June 26, th International Symposium on Molecular Spectroscopy 64 ZnS 66 ZnS 67 ZnS 68 ZnS J’J’ J”J” v  obs-calc  obs-calc  obs-calc  obs-calc < Transition Frequencies

10 June 26, th International Symposium on Molecular Spectroscopy Constants 64 ZnS 66 ZnS 67 ZnS 68 ZnS B0B (51) ) (50) (50) D0D (18) (17) (17) (17) rms BeBe (81) (80) ee (71) (73) DeDe (29) (27) ee (25) (24) r e (Å)  e (cm -1 )  e x e (cm -1 ) D E,v=0 (eV)3.12 Rotational and equilibrium constants for ZnS ( 1  + ) a. a) In MHz unless otherwise indicated. Data fit using SPFIT (Pickett 1991) 7-8 transitions measured for 4 isotopologues Hyperfine structure from 67 Zn (I = 5/2) not observed v = 0 and v = 1 for 64 ZnS and 66 ZnS r e = Å (theory: r e ~ Å)

11 June 26, th International Symposium on Molecular Spectroscopy 3d Sulfide and Oxide Bond Lengths “double-hump” structure r 0 : TiO, VO, CrO, MnO, FeO, CuO, ScS, VS, MnS, FeS, CoS r e : ScO, CoO, NiO, ZnO, TiS, CrS, NiS, CuS, ZnS CuO-ZnO decrease: ~0.02 Å CuS-ZnS decrease: ~0.003 Å Less stabilization gained from addition of electron to the valence  orbital in ZnS

12 June 26, th International Symposium on Molecular Spectroscopy Dissociation Energy Value estimated in this work higher than all previous studies Is Morse potential good assumption? D E (ZnS) = 3.12 eV D E (ZnO) = 3.41 eV D E (ZnF) = 3.12 eV D E (ZnCl) = 2.73 eV Present Study Peterson 2007 de Maria 1965 Boldyrev 1997

13 June 26, th International Symposium on Molecular Spectroscopy Summary Rotational spectra of four isotopologues of ZnS have been measured Rotational and equilibrium constants have been determined This work agrees well with theory with regards to bond lengths Dissociation energy is significantly higher than previous theoretical and experimental (mass spec) studies indicate Similarities in bonding trends between oxides and sulfides

14 June 26, th International Symposium on Molecular Spectroscopy Acknowledgements Professor Lucy Ziurys Dr. DeWayne Halfen Robin Pulliam, Brent Harris, Ming Sun, Emmy Tenenbaum, Jessica Dodd, Gilles Adande, Matthew Bucchino, and Jie Min Funding- NSF and NASA


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