1. R. S. RAM and P. F. BERNATH Department of Chemistry, University of York, Heslington, York YO10 5DD, UK. and Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.

2. INTRODUCTION CN is known for more than a century [A 2 Π-X 2 Σ +, B 2 Σ + -X 2 Σ + ] Comets (Greenstein 1958; Ferrin 1977; Fray et al. 2005), Stars (Fowler & Shaw 1912; Lambert et al. 1984) The Sun (Uitenbroek & Tritschler 2007) Circumstellar shells (Wootten et al. 1982; Wiedemann et al. 1991) Interstellar clouds (Turner & Gammon 1975; Meyer & Jura 1985) Integrated light of galaxies (Riffel et al. 2007) Red Rectangle nebula [HD 44179] (Hobbs et al. 2004). CN provides a probe of C and N abundances & isotopic ratios

3. Interstellar CN Violet 0-0 Diffuse interstellar cloud absorption towards the star HD169454 T rot = 3 K (same temperature as the cosmic background radiation) 12 C/ 13 C=38 Gredel et al. AA, 251, 625 (1991)

4. 12 C/ 13 C=115, 14 N/ 15 N=140 Arpigny et al. Science 301, 1522 (2003) Comet LINEAR-CN Violet Emission (A) (B) Signatures of 13 C and 15 N in the Spectrum of Comet LINEAR (C/2000 WM1) C 15 N 13 CN 12 CN

5. A 2 П-X 2 Σ + (red system) Hosinsky et al. A&AS 25, 1 (1977), Phys. Scr. 25, 291 (1982) [v´=0-4, v˝=0-2] Ram et al. ApJ 188, 500 (2010) [v´=0-8, v˝=0-5 ] First measurements in 4000-10000 cm -1 region Jenkins & Wooldridge Phys. Rev. 53, 137 (1938) [0-0, 0-1 and 0-2 bands] B 2 Σ + -X 2 Σ + (violet system) 12 C/ 13 C ratios in carbon stars and comets Carbon stars: 4.5 in a J-type carbon star [WZ Cas, Lambert ApJ 284, 223 (1984)] Comets: 91±3.6 [Manfroid et al. A&A 503, 613 (2009)] Infrared and Microwave Hempel et al. M. Phys. 101, 589 (2003), and Hübner et al. Sp. Acta 61, 57 (2005) Bogey et al. CJP 62, 1248 (1984), CP 102, 141 (1986) PREVIOUS WORK ON 13 C 14 N

6. 13 C 14 N, A 2 Π-X 2 Σ + Ram et al. ApJ 188 500 (2010) 47 4.5 12 C/ 13 C

7. 13 C 14 N,B 2 Σ + -X 2 Σ + Jenkins & Wooldridge, Phys. Rev. 53, 137 (1938) analyzed 0-0, 0-1 & 0-2 bands using spectra at grating resolution Rotational analysis of 52 bands with vibrational levels v´= 0 to 15 & v˝= 0 to 15, except bands involving v´ & v˝=13 which are affected by strong perturbations. Previous work Present work

8. EXPERIMENTAL McMath-Pierce Solar Telescope of NSO at Kitt Peak Reaction of 14 N 2 and 13 CH 4 in Ar Regular microwave & active nitrogen afterglow discharge Resolution: 0.02-0.05 cm -1 No. of scans: 20-70 Calibration: Ar line measurements by Whaling et al. (2002) Spectra were recorded by J. Brault and S. Davis

9. 13 C 14 N, B 2 Σ + -X 2 Σ + Irregular intensity pattern v´ & v˝=13 levels are perturbed

12. CONSTANTS FOR THE X 2 Σ + STATE

13. EQUILIBRIUM CONSTANTS: X 2 Σ + STATE

14. CONSTANTS FOR THE B 2 Σ + STATE

15. A 2 Π-X 2 Σ + HIGHER VIBRATIONAL BANDS 15-7 18-9 21-11 16-8 18-10 8-3 19-11 17-9 20-10

16. SUMMARY The spectra of 13 C 14 N (violet) have been reinvestigated using a Fourier transform spectrometer. 52 bands with v´, v˝ ≤15 have been rotationally analyzed and improved spectroscopic constants have been obtained. This analysis provides a large set of precise line positions useful for isotopic abundance analysis in comets. Analysis of some B 2 Σ + -A 2 Π bands and higher vibrational bands of the A 2 Π-X 2 Σ + transition is in progress.

17. ACKNOWLEDGMENTS LEVERHULME TRUST NASA LABORATORY ASTROPHYSICS NATIONAL SOLAR OBSERVATORY