64 th OSU International Symposium on Molecular Spectroscopy

5 atoms, 9 normal modes μ a = (40) D, μ c = (33) D Inversion transitions ( ) due to tunneling protons through low potential barrier ( 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 cm D Kisiel,Krasnicki,2  Winnewisser, 63 rd OSU, WK08, (2008) astrophysical:Turner et al., Astrophys. J. 201, L149 (1975) Lines emission in Sgr B2

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

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

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

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 : C abundance 1.07%

15 ND 2 CN Relative intensity: ND 2 CN : NHDCN : NH 2 CN 1 : 1 : 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

Blue – 0 + White – 0 - Blue – 0 + White – 0 -

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

F bc term used only for the HDNCN species

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

ΔE isot. - ΔE ND 2 CN ND 2 13 CNND 2 C 15 N 15 ND 2 CN obs. / cm calc./ cm ΔE( )ND 2 CN obs. / cm (9) calc./ cm ΔE( )NHDCN obs. / cm (4) calc./ cm ΔE isot. - ΔE NHDCN NHD 13 CNNHDC 15 N 15 NHDCN obs. / cm calc./ cm ΔE( )NH 2 CN obs. / cm (4) calc./ cm ΔE isot. - ΔE NH 2 CN NH 2 13 CN obs. / cm calc./ cm 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

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.

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.