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Department of Chemistry, Radio Spectroscopy Group

University of North Texas

Radio Spectroscopy Group Meetings

In these group meetings we survey the literature, find work by other rotational spectroscopy groups, and endeavor to reproduce their line listings from their published constants. We also consider re-fitting data. In the following listing the publication reference is given, followed by the group member dealing with the work, which is then followed by relevant SPCAT/SPFIT input files created by a North Texas Radio Spectroscopy Group member (titles in bold are our work):

1. Millimeter-wave spectroscopy of a-alanine, Y. Hirata, S. Kubota, S. Watanabe, T. Momose and K. Kawaguchi, J. Mol. Spectrosc. 251 (2008) 314-318. Discussed by Kerry Etchison (conformer IIa) .var file, .int file . (a-type transitions, Watson A reduced Hamiltonian).

2. Fourier transform microwave spectroscopy of pyridine-neon, B. Velino and W. Caminati, J. Mol. Spectrosc. 251 (2008) 176-179. Discussed by Chris Dewberry (normal species) .var file, .int file .(a-type transitions, Watson S reduced Hamiltonian, nitrogen nuclear spin).

3. The lamb-dip spectrum of methylcyanide: precise rotational transition frequencies and improved ground-state rotational parameters, G. Cazzoli and C. Puzzarini, J. Mol. Spectrosc. 240 (2006) 153-163. Discussed by Smitty Grubbs, .var file , .int file. (Symmetric top, nitrogen nuclear spin, high order centrifugal distortion constants).

4. Microwave spectrum of 4-ethylcyclohexanone, S. Ka, I. Park, J.J. Oh, J. Mol. Spectrosc. 251 (2008) 374-377. Discussed by Kerry Etchison, .var file, .int file. (a-, b- and c-type transitions, Watson S reduced Hamiltonian).

5. The submillimeter-wave spectrum of propionitrile (C2H5CN), J. C. Pearson, K. V. L. N. Sastry, E. Herbst and F. C. De Lucia, The Astrophysical Journal Supplement Series, 93 (1994) 589-610. Discussed by Chris Dewberry, .var file, .int file .(a-, and b-type transitions, Watson A reduced Hamiltonian).

6. The rotational spectrum of epifluorohydrin measured by chirped-pulse Fourier transform microwave spectroscopy, G. G. Brown, B. C. Dian, K. O. Douglass, S. M. Geyer and B. H. Pate, J. Mol. Spectrosc. 238 (2006) 200-212. Discussed by Smitty Grubbs (conformer 1), .var file, .int file.(a-, b- and c-type transitions, Watson A reduced Hamiltonian).

7. The microwave spectrum and structure of 1,1,1,3,3,3-hexafluoropropane, Freon R236fa, M. Onda, K. Tsuda and E. Sakamoto, J. Mol. Spectrosc. 780-781 (2006) 222-224. .var file, .int file. (c-type transitions, Watson A reduced Hamiltonian).

8. Rotational spectrum and molecular properties of the dinitrogen-chlorine monofluoride complex, S. A. Cooke, G. Cotti, K. Hinds, J. H. Holloway, A. C. Legon and D. G. Lister, J. Chem. Soc., Faraday Trans., 92 (1996) 2671-2676. .var file, .int file. (Linear complex, 3 nuclear spins).

9. The pure rotational spectrum of pivaloyl chloride, (CH3)3CCOCl, between 800 and 18800 MHz, G. S. Grubbs II, C. T. Dewberry, K. C. Etchison, M. M. Serafin, S. A. Peebles and S. A. Cooke, J. Mol. Spectrosc., 251 (2008) 378-383. Our work. .par file, .lin file, .int file. (Watson A reduced Hamiltonian, off-diagonal component in the Cl coupling tensor).

10. Microwave spectra, inversion splittings and quadrupole coupling constants of NHDCl and ND2Cl, E. Masuko, Y. Hamada, A. Mizguchi, H. Fukushi, N. Kuze and T. Sakaizumi, J. Mol. Spectrosc. 253 (2009) 77-87. .var file, .int file. (Watson A reduced Hamiltonian, two nuclear spins).

11. Fourier transform microwave spectroscopy of the HCCN radical. Determination of the hyperfine coupling constants, Y. Endo and Y. Ohshima, J. Chem. Phys., 98 (1993) 6618-6623. Discussed by Chris Dewberry, .var file, .int file. (triplet sigma radical with H and N nuclear spins).

12. Internal rotation effects in the pulsed jet rotational spectrum of the trifluoromethane-carbon dioxide dimer, M. M. Serafin, R. A. Peebles, and S. A. Peebles, J. Mol. Spectrosc., 250 (2008) 1-7. Discussed by Kerry Etchison, .var file, .int file. (a-type and c-type, A state only, Watson S reduction)

13. The hyperfine structure of germyl chloride, G. Wlodarczak, N. Heineking and H. Dreizler, J. Mol. Spectrosc. 147 (1991) 252-259. Discussed by Smitty Grubbs, .var file, .int file. (Symmetric top with two nuclear spins).

This week, the assignment involves attempting to fit spectroscopic constants to a set of lines. Step 1 is to make some sort of plot of the lines, either by hand, or through excel or some other means. Then you need to look at spacings between the lines and start thinking about the symmetry of the molecule (linear, symmetric,asymmetric). Townes and Schawlow/Gordy and Cook can help with the sorts of spacings you might expect between rigid rotor energy levels -
that should get you started. None of your molecules have nuclear spins> 0, so no need to worry about nuclear electric quadrupole coupling constants (eQq), or nuclear spin-rotation constants (C_I terms). They are closed shell molecules. When you feel comfortable, make a .lin
and .par file and try some fits. Good luck, do the best you can: Here are your line lists:

Kerry lines, Chris lines, and Smitty lines.

Useful Links:

instructions from JPL