1. 64 th OSU International Symposium on Molecular Spectroscopy

2. 5 atoms, 9 normal modes μ a = 4.3192(40) D, μ c = - 0.9559(33) D Inversion transitions (0 + - 0 - ) due to tunneling protons through low potential barrier (469.12 cm -1 ) cmw: + ND 2 CN, NHDCNMillen et. al, J.Mol.Spectrosc. 8, 153 (1962) D & 15 N - isototopologuesTyler et. al, J.Mol.Spectrosc. 43, 248 (1972) to 120 GHz:Johnson et. al Astrophys. J. 208, 245 (1976) srb analysis: + D & 15 NBrown et. al, J.Mol.Spectrosc. 114, 257 (1985) to 500 GHz: + DRead et. al, J.Mol.Spectrosc. 115, 316 (1986) 14 N splitting:Brown et al., J.Mol.Spectrosc. 130, 213 (1988) FT far ir:Birk,Winnewisser, J.Mol.Spectrosc. 159, 69 (1993) ir to 980 cm - 1 :Moruzzi,Jabs,2  Winnewisser, J.Mol.Spectrosc. 190, 353 (1998) mmw + ir 8-350 cm - 1 + D Kisiel,Krasnicki,2  Winnewisser, 63 rd OSU, WK08, (2008) astrophysical:Turner et al., Astrophys. J. 201, L149 (1975) Lines emission in Sgr B2

3. MMW spectra measured on BWO based spectrometers in Giessen and Köln 118-179 GHz, 202-221 GHz, 570-650 GHz Wolfgang Jabs, Giessen 1998 Reduced quartic-quadratic potential V(z)=A(z 4 +Bz 2 ) z=const*m red *A -⅟ 2 *Ф

4. a – type (0 + → 0 +, 0 - → 0 - ) c – type (0 + → 0 -, 0 - → 0 + ) Experimental spectrum

5. ND 2 CN NHDCN NH 2 CN a R, J” = 7, {0 +, 0 - } Relative intensity: ND 2 CN : NHDCN : NH 2 CN 1 : 1 : 0.15

6. ND 2 13 CN a R, J” = 7, {0 +, 0 - } NHD 13 CN NH 2 13 CN Relative intensity: ND 2 CN : NHDCN : NH 2 CN 1 : 1 : 0.15 13 C abundance 1.07%

7. 15 ND 2 CN Relative intensity: ND 2 CN : NHDCN : NH 2 CN 1 : 1 : 0.15 13 C abundance 1.07% 15 N abundance 0.368% a R, J” = 7, {0 +, 0 - } 15 NHDCN NHDC 15 N ND 2 C 15 N

8. Blue – 0 + White – 0 - Blue – 0 + White – 0 -

9. Ka=5Ka=5 Ka=5Ka=5 Ka=4Ka=4 Ka=4Ka=4 0+0+ 0-0- 0-0- 0+0+ 2:1 alternation of statistical weights Blue – 0 + White – 0 - Blue – 0 + White – 0 -

10. 0+0+ 0-0- F bc term used only for the HDNCN species

11. + similar results for NH 2 13 CN, NHD 13 CN, ND 2 13 CN, NHDC 15 N, 15 ND 2 CN, 15 NHDCN  E = 494551.901(27) MHz F ca = 267.6102(19) MHz For ND 2 CN

12. ΔE isot. - ΔE ND 2 CN ND 2 13 CNND 2 C 15 N 15 ND 2 CN obs. / cm -1 0.022-0.011-0.633 calc./ cm -1 0.049-0.064-0.771 ΔE(0 - - 0 + )ND 2 CN obs. / cm -1 16.4965304(9) calc./ cm -1 15.387 ΔE(0 - - 0 + )NHDCN obs. / cm -1 32.089281(4) calc./ cm -1 31.062 ΔE isot. - ΔE NHDCN NHD 13 CNNHDC 15 N 15 NHDCN obs. / cm -1 0.029-0.001-0.780 calc./ cm -1 0.062-0.082-0.986 ΔE(0 - - 0 + )NH 2 CN obs. / cm -1 49.567984(4) calc./ cm -1 49.567 ΔE isot. - ΔE NH 2 CN NH 2 13 CN obs. / cm -1 0.062 calc./ cm -1 0.069 Results from obtained by using the reduced quartic-quadratic potential V(z)=A(z 4 +Bz 2 ) and program ANHARM Results from obtained by using the reduced quartic-quadratic potential V(z)=A(z 4 +Bz 2 ) and program ANHARM A, B parameters scaled for isotopic species based on reduced mass for inversion motion in cyanamide A, B parameters scaled for isotopic species based on reduced mass for inversion motion in cyanamide

15. The mmw and smm rotational spectra of 7 rare isotopic species of cyanamide have been assigned, up to K a =7 and J”=34 (ca 200 lines for each species). Spectroscopic information on 15 ND 2 CN, ND 2 C 15 N has been considerably improved. The spectra of NH 2 13 CN, NHD 13 CN, ND 2 13 CN, 15 NHDCN, NHDC 15 N have been assigned for the first time. The structure of cyanamide has been derived. We hope that further progress in understanding of the cyanamide geometry will come from semi-experimental equilibrium structure.

16. We are indebted to Wolfgang Jabs (Giessen) who recorded all of the spectra used in this work. We are grateful to Ewa Bialkowska-Jaworska (Warszawa) for help with ab initio calculations.