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June 17- 21, 2013 68 th International Symposium on Molecular Spectroscopy Millimeter and Sub-millimeter Spectroscopy of CrCCH (X 6 Σ + ) Jie Min and L.M.

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Presentation on theme: "June 17- 21, 2013 68 th International Symposium on Molecular Spectroscopy Millimeter and Sub-millimeter Spectroscopy of CrCCH (X 6 Σ + ) Jie Min and L.M."— Presentation transcript:

1 June , th International Symposium on Molecular Spectroscopy Millimeter and Sub-millimeter Spectroscopy of CrCCH (X 6 Σ + ) Jie Min and L.M. Ziurys Department of Astronomy Department of Chemistry and Biochemistry Steward Observatory University of Arizona ~

2 June , th International Symposium on Molecular Spectroscopy Importance of Metal Monoacetylides Small transition metal organometallic radicals model systems Examine fundamental interactions between metal and ligand Test the theoretical studies of bonding into d-shells Metal (3d) monoacetylide species of interest MCCH fragments serve as intermediates in catalysis, synthesis Limited spectroscopic information for 3d Monoacetylies Previous gas-phase spectroscopy: CrCCH (X 6 Σ + ): Electronic spectroscopy (R2PI) by Morse group (2004) CuCCH (X 1 Σ + ) & ZnCCH (X 2 Σ + ): FTMW/mm-wave by Ziurys group (Sun et al. 2010; Min et al. 2012) Examine periodic trends in 3d MCCH series Conduct mm-wave search for CrCCH

3 June , th International Symposium on Molecular Spectroscopy Past mm-wave studies of CuCCH and ZnCCH: VERY Difficult Synthesis used Broida ovens; based on our FTMW data Try different approach: Cr(CO) 6 as chromium source AC discharge in argon & HCCH Velocity modulation spectrometer Radiation Source: Gunn oscillators with Schottky diode multipliers ( GHz) Reaction Chamber: Glass cell chilled by methanol Gaussian beam optics Detector: InSb bolometer Source-modulation and detection at 2f Based on estimates of B, λ, γ (Morse) Millimeter-Wave Direct Absorption Study of CrCCH

4 June , th International Symposium on Molecular Spectroscopy Raw Data: Search continuously over ~30 GHz Pattern of Sextets emerged …

5 June , th International Symposium on Molecular Spectroscopy ~ Pure rotational data: exhibit sextets Note weaker lines !

6 June , th International Symposium on Molecular Spectroscopy Confirmation with CrCCD To confirm identification, searched for CrCCD No previous constants, scaled from CrCCH constants Method: Cr(CO) 6 + DCCD in AC discharge Five transitions measured, each consisting of sextets

7 June , th International Symposium on Molecular Spectroscopy Parameter (MHz)CrCCHCrCCDCrCCH (Morse) B (37) (39)3843 D (50) (45)-- γ40.703(28)44.849(31)39.6 γDγD (90) λ8691 (21)8672(26)8703 λDλD (83) (85)-- rms Searching for new transitions with FTMW system Attempt 13 C substitution to establish a good structure Current Spectroscopic Analysis H eff = H Rot + H SR + H SS Fit 10 transitions of CrCCH (60 lines); 5 transitions of CrCCD (30 lines) Improved constants, including all centrifugal distortion terms

8 June , th International Symposium on Molecular Spectroscopy J=N J=N+1 J=N-1 J=NJ=N-1J=N+1 J=NJ=N-1 J=N+1 Searches for CrC (X 3 Σ - ) Based on Morse 2010 (B, γ, λ) Uncertainties in spin splittings Searched over ~100 GHz on VM machine Cr(CO) 6 + CH 4 in AC discharge

9 June , th International Symposium on Molecular Spectroscopy J = N+1 J = NJ = N-1 N = N = N = N = Frequency (GHz)

10 June , th International Symposium on Molecular Spectroscopy Parameter (MHz)CrCCrC (Morse) B (37)3843 D (50)-- γ46.703(28)39.6 λ8891 (21)8703 λDλD (83)-- rms r0r Fit 7 transitions (three spin components each) of CrC in X 3 Σ - state Following effective Hamiltonian: H eff = H Rot + H SR + H SS Improved constants, including all centrifugal distortion terms Preliminary Spectroscopic Analysis

11 June , th International Symposium on Molecular Spectroscopy First pure rotational study of CrCCH and CrC Confirmed 6 Σ and 3 Σ ground electronic states, respectively Monoacetylide: Spectra of CrCCD also measured Searching for other isotopologues to establish structure (FTMW) CrC: 13 C substitution Other 3d MCCH and MC species Results and Future Directions Funding: NSF


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