1. The Millimeter/Submillimeter Spectrum of the CCP (X 2  r ) Radical DeWayne T. Halfen Steward Observatory, Arizona Radio Observatory, University of Arizona Dennis Clouthier Department of Chemistry, University of Kentucky Lucy M. Ziurys Departments of Chemistry and Astronomy, Steward Observatory, Arizona Radio Observatory, University of Arizona June 20, 2008

2. Why CCP ? Chemical aspect –Dicarbides have 2 possible structures: cyclic T-shaped or linear –Cyclic: NaC 2, MgC 2, AlC 2, SiC 2 (Largo et al. 2004; Chasovskikh et al. 2007; Thaddeus et al. 1984) –Linear: CCS, CCCl (Saito et al. 1987; Sumiyoshi et al. 2003) Astronomical Aspect –Five phosphorus-bearing molecules found in circumstellar envelopes, including CP and HCP (Guélin et al. 1990; Agúndez et al. 2007; Milam et al. 2008) –Multiple carbon-chain species present as well, up to C 8 –CCP is next logical molecule to search for (see FD07) Phosphorus-bearing species in space PNCPHCP POPH 3 Are there more? Milam et al. 2008

3. Theoretical calculations by Largo et al. (1994), El-Yazal et al. (1997), and Sunahori, Wie, Clouthier (2007) –Predicted linear CCP structure and 2  r ground state –Calculated the bond lengths, dipole moment (3.3-3.6 D), and vibrational frequencies First detected in lab by Sunahori, Wie, Clouthier (2007) –Measured LIF and wavelength- resolved emission spectrum of the 2  –X 2  r transition Sunahori, Wie, Clouthier 2007 Past Work on CCP

4. Millimeter-wave Direct Absorption Spectrometer

5. Detector Radiation Source Gas Cell Reactant

6. Gas-Phase Synthesis of CCP Gas-phase P source –Glass oven in an attachment at the end of the cell –Heated red phosphorus to 300 o C Added 1-2 mtorr of acetone free HCCH –Dry Ice/Acetone trap necessary (-80 o C) 40 mtorr of Ar carrier gas also added AC discharge –200 W at 600  –Blue glow in cell Gas-phase P source Ring Electrodes Glass Attachment Sample Oven Cooling Jacket + - Caution: Red P + heat in vacuum makes white P

7. Rotational Spectrum of CCP (X 2  r ) Initially searched 30 GHz –Used predictions based on Sunahori et al. (2007) study –Identified doublets decreasing in separation with increasing frequency –  = 1/2 of a 2  r state Searched for  = 3/2 state –Conditions optimized –Another 25 GHz selectively scanned –  = 3/2 identified as doublet increasing in separation with increasing frequency –v 2 = 1 also observed  = 1/2  = 3/2 v 2 = 1 CCP Search Stick Spectrum

8.  = 1/2 and 3/2 spin-orbit ladders, e and f lambda-doublets Phosphorus hyperfine I(P) = 1/2 observed at low frequency Halfen, Sun, Clouthier, Ziurys 2008

10. 33  = 1/2 transitions measured from 120-540 GHz 18  = 3/2 transitions recorded from 301-545 GHz 113 lines measured Fine structure resolved for most transitions Selected Rotational Frequencies of CCP (X 2  r ) JJ JFF F  Parity obs obs - calc 10.5  9.511  101/2e133577.5110.044 10  91/2e133579.0490.008 11  101/2f133623.741-0.006 10  91/2f133625.6000.016 21.5  20.5 a 1/2e273489.5120.010 a 1/2f273519.557-0.019 26.5  25.5 a 3/2e 340200.9360.094 a 3/2f 340200.9360.094 32.5  31.5 a 1/2e413281.401-0.009 a 1/2f413287.070-0.009 a 3/2e 417112.006-0.037 41.5  40.5 a 3/2f 417113.5970.034 a 3/2e 532346.2870.019 a 3/2f 532349.624-0.057 Transition Frequencies of CCP (X 2  r )

11. Spectroscopic Constants for CCP ParameterThis work (MHz)Theoretical B6392.4138(26)6390 a, 6367 b D0.0022595(22) H9.50(59) x 10 -9 A4212195 c ADAD 40.536(10) AHAH -2.782(86) x 10 -4 ALAL 4.8(2.3) x 10 -9 p+2q50.0127(96) (p+2q) D -0.015124(47) (p+2q) H 7.29(21) x 10 -7 q0.0109 c qDqD 6.57(17) x 10 -5 h 1/2 484.220(30) h 1/2D 0.8337(91) d 1/2 632.538(16) rms0.050 a Sunahori et al. (2008) b El-Yazal et al. (1997) c Held fixed. Rotational constant B agrees well with theoretical predictions Lambda-doubling constant p+2q well determined –q held fixed, not defined (3  ) in final fit Hyperfine splitting only observed in  = 1/2 state –Only h 1/2 and d 1/2 could be established Data analyzed to experimental accuracy of 50 kHz Spectroscopic Analysis of CCP

12. Confirmed CCP linear molecule –More discussion of its structure next talk by M. Sun (FC03) With these rest frequencies, we found CCP in space –See talk FD07 Many other interesting phosphorus species could be measured in the laboratory Summary and Future Work

13. Lucy Ziurys Dennis Clouthier Emmy Tenenbaum Ming Sun Robin Pulliam Lindsay Zack Jessica Dodd Gilles Adande NASA Astrobiology Institute NSF Astronomy and Astrophysics Postdoctoral Fellowship Acknowledgements