1. High-resolution Fourier transform emission spectroscopy of the A 2  + – X 2  transition of the BrCN + ion. June 20, 2005, Ohio state Univ. Yoshihiro Nakashima (a), Tomoki Ogawa, Maki Matsuo, and Keiichi Tanaka Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan (a) : Ozone Layer Research Project, National Institute for Environmental Studies (NIES), National Institute for Environmental Studies (NIES), Ibaraki, Japan Ibaraki, Japan

2. A =  1477 cm -1 1477cm -1 Introduction Influence of the large spin-orbit interaction large spin-orbit interaction on the Renner-Teller effect  2 = 287.24(20) cm -1 287.24 cm -1 BrCN + ion Renner-Teller effect Renner-Teller effect Large spin-orbit interaction Large spin-orbit interaction X 2  Electronic ground state : X 2 

3. Previous works 2. M. A. Hanratty et al. B 2  3/2  X 2  3/2 LIF spectra of the B 2  3/2  X 2  3/2 transition 4. C. Salud et al. Infrared diode laser spectroscopy of the 1 (CN str.) fundamental band 1 (CN str.) fundamental band X 2  3/2 of the X 2  3/2  state 1. J.Fulara et al. Low-resolution emission spectra B 2  3/2  X 2  3/2 of the B 2  3/2  X 2  3/2 and A 2    X 2  A 2    X 2  transitions A 2  + X 2   B 2   0 13,700 19,230 cm -1 (001) (002) (012) (100) 3. M. Rosslein et al. LIF spectra of the B 2  3/2  X 2  3/2 transition to determine the r s -structure r s -structure of BrCN +

4. Experimental He (1.0 Torr) BrCN (2-3 mTorr) resolution : 0.02 cm -1 spectral region : 11500 – 15000 cm -1 accumulation time : 40 hrs. Penning ionization He*(2 3 S) + BrCN BrCN + + He(1 1 S) (I.P.=12.08 eV)

5. Observed spectrum ( A 2  + - X 2   ) (010)-(000) (010)-(010) (000)-(000) (001)-(011) (010)-(001) (100)-(100) (001)-(001)  =3/2 (000)-(010) A 2  + -  2  (000)-(100)  =1/2 (000)-(000) (010)-(010) (001)-(001) (000)-(010) A 2  + -  2 

6. A 2  + (000) - X 2  3/2 (000) transition P1P1 R 21 P 21 + Q 1 R 1 + Q 21

7. A 2  + (000) - X 2  3/2 (000) transition P 1 branch 79 BrCN + J’’=35.5J’’=39.5 81 BrCN + J’’=35.5J’’=39.5

8. Molecular constants (unit : cm -1 ) state constant  =3/2  =1/2 D.L. (  =3/2) A 2  +  13697.1192(13) 12220.6523(46) B 0.1411698(51) 10 7 D 0.346(16)  0.017752(37) X 2   B  0.1414036(47) 0.1416173(62) 0.1413799(41) 10 7 D 0.307(15) 0.347(11) 0.158(23)  q + p/2  0.00600(11) eff A 2  + (000) – X 2   (000) transition of 79 BrCN + 79 B 000 = 0.1415105(32) cm -1 81 B 000 = 0.1406757(41) cm -1 Rotational constant B 000 B 3/2 = B 000 ( 1 + B 000 /A eff ) B 1/2 = B 000 ( 1  B 000 /A eff ) eff A eff = 1/2 – 3/2 79 A eff =  1476.4669(48) cm -1 81 A eff =  1476.4841(60) cm -1 Effective spin-orbit interaction constant A eff low resolution emission spectroscopy A =  1477 cm -1

9. r 0 -structure I =  m k z k 2 0 =  m k z k  I = z Br 2  m Br  m k  m Br +  m k BrCN × z Br zCzC zNzN G species electronic state r BrC r CN BrCN X 1  + 1.789 1.158 BrCN + X 2  1.788(54) 1.103(78) 1.745(7) a 1.195(8) a A 2  + 1.814(61) 1.064(90) unit : A a : The r s -structure determined by Rosslein et al.

10. Main electronic configuration (3  ) 2 (1  ) 4 (4  ) 2 (2  ) 4 : BrCN (X 1  + ) (3  ) 2 (1  ) 4 (4  ) 2 (2  ) 3 : BrCN + (X 2  ) (3  ) 2 (1  ) 4 (4  ) 1 (2  ) 4 : BrCN + (A 2  + ) 4p (Br) –  (CN) p z (N) (non-bonding) Geometrical change is small ! p (Br) (non-bonding)

11. A 2  + -  2  transition P2P2 R2R2 P 12 R 12

12. Molecular constants (unit : cm -1 ) state constant  2   2  A 2  + (000) 13410.1135(12) 11921.6949(21) B 0.14117 a 10 7 D 0.346 a  0.0178 a X 2  (010)  B 0.1419339(19) 0.1420853(25) 10 7 D 0.3165(60) 0.3035(58) p  0.020312(27)  0.018749(46) A 2  + (000) – X 2   (010) transition of 79 BrCN + Rotational constant B 010 79 B 010 = 0.1420111(23) cm -1 81 B 010 = 0.1412625(25) cm -1 B  = B 010  [ (B 010 –  /2) cos 2  ] 2 /2r B  = B 010  [ (B 010 –  /2) cos 2  ] 2 /2r a : Fixed to the values derived from the rotational analysis of the origin bands.

13. A 2  + (000) X 2  (010)  2 2  2 2 2r2r Energy difference between  2  and  2  Energy difference : 2r Energy difference : 2r 2r = [ A eff 2 + (2  2 ) 2 ] 1/2 =  -  2 79 r = 1488.4186(24) cm -1 2 81 r = 1488.4050(30) cm -1   2r > |A eff | (= 1476.47 cm -1 ) Small influence of the Renner-Teller effect on the X 2  state of BrCN +

14. Renner parameter  p = 4B 010  2 /2r p = 4B 010  2 /2r state constant 79 BrCN + 81 BrCN +  2  p  0.020312(27)  0.020187(32)  2  p  0.018749(46)  0.018563(52) B 010 0.1420111(23) 0.1412625(25) 2r 1488.4186(24) 1488.4050(30)  2 287.24(20) a 79  =  0.18529(27) 81  =  0.18512(32)  : Renner parameter p :  –  type doubling constant p :  –  type doubling constant BO 2 (X 2  )  =  0.19 CO 2 + (X 2  u )  =  0.190 a : Low resolution emission spectroscopy (Fulara et al.)

15. Wave functions for  2  and  2  Wave functions for  2  and  2  sin 2  =  2 /2 cos 2  = A eff /2 sin 2  : cos 2  = 0.0040 : 0.9959 Large spin-orbit interaction ! Influence of the Renner-Teller effect on the X 2  state of BrCN + is small !

16. Summary A 2  + - X 2  transition 1. Near-infrared emission spectrum of the A 2  + - X 2  transition of the BrCN + ionFT spectroscopy. BrCN + ion was observed by FT spectroscopy. Rotational analysis 2. Rotational analysis of the four bands, A 2  + (000) - X 2   (000) (  =3/2 and 1/2 ) A 2  + (000) -  2  and A 2  + (000) -  2 , A 2  + (000) -  2  and A 2  + (000) -  2 , was performed to determine the molecular constants. geometrical difference 3. The r 0 -structures of BrCN + were obtained and geometrical difference between BrCN and BrCN + was small. between BrCN and BrCN + was small. Renner parameter  =  0.185 4. Renner parameter was determined to be  =  0.185, and the influence of the Renner-Teller effect on X 2  was turned out large spin-orbit interaction to be small due to the large spin-orbit interaction.

17. Observed spectrum Nine vibronic bands of the A 2  + - X 2   transition Four vibronic bands of the A 2  + - X 2   transition A 2  + X 2  (000) (100) (010) (001) (100) (010) (001) 22 22 2   2   0 1,000 2,000 3,000 13,697 cm -1

18. BrCN + ion Renner-Teller effect Splitting of the vibronic state by the excitation of the bending vibration X 2  Electronic ground state : X 2  spin-orbit interaction Introduction Vibronic interaction

19. V + = a ( 1 +  ) (  r) 2 + … V - = a ( 1 –  ) (  r) 2 + … |  |<1|  |>1 NCO, N 2 O + ( X 2  ) NH 2 ( X 2 B 1, A 2  )  : Renner parameter Bending potential function

20. Molecular constants (unit : cm -1 ) state constant FT + D.L. D.L. LIF A 2  + 3/2 13697.1192(13) B 0.1411698(51) 10 7 D 0.346(16)  0.017752(37) X 2   B 3/2 0.1414036(47) 0.1413799(41) 0.141536(47) 10 7 D 0.307(15) 0.158(23) 0.86(28) state constant FT + D.L. D.L. LIF A 2  + 3/2 13697.1613(13) B 0.1403581(50) 10 7 D 0.299(16)  0.017672(37) X 2   B 3/2 0.1405939(47) 0.140582(11) 0.140859(86) 10 7 D 0.262(14) 0.147(60) 1.5(56) 79 BrCN + 81 BrCN + eff A 2  + (000) – X 2  3/2 (000) transition

21. Molecular constants (unit : cm -1 ) state constant 79 BrCN + 81 BrCN + A 2  + 1/2 12220.6523(46) 12220.6762(59) B 0.14117 a 0.14036 a 10 7 D 0.346 a 0.299 a  0.0178 a  0.0177 a X 2   B 1/2 0.1416173(62) 0.1407575(67) 10 7 D 0.347(11) 0.214(16) p/2 + q 0.00600(11) 0.00501(15) eff 79 B 000 = 0.1415105(32) cm -1 81 B 000 = 0.1406757(41) cm -1 Rotational constant B 000 B 3/2 = B 000 ( 1 + B 000 /A ) B 1/2 = B 000 ( 1  B 000 /A ) eff A 2  + (000) – X 2  1/2 (000) transition

22. Molecular constants (unit : cm -1 ) state constant 79 BrCN + 81 BrCN + A 2  +  13410.1135(12) 13410.2424(17) B 0.14117 a 0.14036 a 10 7 D 0.346 a 0.299 a  0.0178 a  0.0177 a  2  B  0.1419339(19) 0.1411504(26) 10 7 D 0.3165(60) 0.3493(79) p  0.020312(27)  0.020187(32) A 2  + -  2  state constant 79 BrCN + 81 BrCN + A 2  +  11921.6949(21) 11921.8374(25) B 0.14117 a 0.14036 a 10 7 D 0.346 a 0.299 a  0.0178 a  0.0177 a  2  B  0.1420853(25) 0.1412934(28) 10 7 D 0.3035(58) 0.3139(66) p  0.018749(46)  0.018563(52) A 2  + -  2 

23. Spin-orbit interaction constant A = 1/2 – 3/2 79 A =  1476.4669(48) cm -1 81 A =  1476.4841(60) cm -1 X 2  (000) A 2  + (000) X 2   X 2   3/2 1/2 A low resolution emission spectroscopy A =  1477 cm -1

24. A 2  + (000) - X 2  1/2 (000) transition P 2 + Q 12 R 12 + Q 2 P 12 R2R2

25. A 2  + -  2  transition P1P1 R1R1 P 21 R 21

26. Renner parameter species A eff  2  79 BrCN +  1497.42  53.223(70)  0.18529(27) BO 2  148.6  86.4  0.19 CNC 26.41 176 0.55 CO 2 +  161.02  96.8  0.190 NCO  95.58  76  0.14 N 2 O +  133.40  79.7  0.1762