Highresolution Fourier transform emission spectroscopy of the A

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High-resolution Fourier transform emission spectroscopy of the A 2 S+ – X 2 P

High-resolution Fourier transform emission spectroscopy of the A 2 S+ – X 2 P transition of the Br. CN+ ion. 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), Ibaraki, Japan June 20, 2005, Ohio state Univ.

Introduction Br. CN+ ion Electronic ground state : X 2 P • Renner-Teller effect

Introduction Br. CN+ ion Electronic ground state : X 2 P • Renner-Teller effect • Large spin-orbit interaction A = -1477 cm-1 w 2 = 287. 24(20) cm-1 Influence of the large spin-orbit interaction on the Renner-Teller effect 287. 24 cm-1 1477 cm-1

Previous works 1. J. Fulara et al. Low-resolution emission spectra 2 2 of the

Previous works 1. J. Fulara et al. Low-resolution emission spectra 2 2 of the B P 3/2 - X P 3/2 and A 2 S+- X 2 P transitions 2. M. A. Hanratty et al. 2 2 LIF spectra of the B P 3/2 - X P 3/2 transition 3. M. Rosslein et al. LIF spectra of the B 2 P 3/2 - X 2 P 3/2 transition to determine the rs-structure of Br. CN+ cm-1 (012) 19, 230 B 2 P 3/2 13, 700 A 2 S + (100) 4. C. Salud et al. Infrared diode laser spectroscopy of the n 1 (CN str. ) fundamental band 2 of the X P 3/2 state (002) (001) 0 X 2 P 3/2

Experimental He (1. 0 Torr) Penning ionization He*(23 S) + Br. CN (I. P.

Experimental He (1. 0 Torr) Penning ionization He*(23 S) + Br. CN (I. P. =12. 08 e. V) Br. CN (2 -3 m. Torr) resolution : 0. 02 cm-1 spectral region : 11500 – 15000 cm-1 accumulation time : 40 hrs. Br. CN+ + He(11 S)

Observed spectrum ( A W=3/2 A 2 S+ - m 2 S A 2

Observed spectrum ( A W=3/2 A 2 S+ - m 2 S A 2 S+ - k 2 S (000)-(100) (000)-(010) X 2 P W ) (000)-(000) (100)-(100) (010)-(001) (000)-(010) (001)-(001)-(011) W=1/2 2 S + - (010)-(010)-(000) (001)-(001) (010)-(010)

A 2 S+ (000) - X 2 P 3/2 (000) transition P 21 +

A 2 S+ (000) - X 2 P 3/2 (000) transition P 21 + Q 1 P 1 R 1 + Q 21 R 21

A 2 S+ (000) P 1 branch J’’=39. 5 - X 2 P 3/2

A 2 S+ (000) P 1 branch J’’=39. 5 - X 2 P 3/2 (000) transition 79 Br. CN+ 81 Br. CN+ J’’=35. 5

Molecular constants (unit : cm-1) A 2 S+(000) – X 2 PW(000) transition of

Molecular constants (unit : cm-1) A 2 S+(000) – X 2 PW(000) transition of 79 Br. CN+ state constant A 2 S+ n. W B 107 D g X 2 PW BWeff 107 D q + p/2 W=3/2 W=1/2 D. L. (W=3/2) 13697. 1192(13) 12220. 6523(46) 0. 1411698(51) 0. 346(16) - 0. 017752(37) 0. 1414036(47) 0. 307(15) 0. 1416173(62) 0. 347(11) 0. 00600(11) 0. 1413799(41) 0. 158(23) Rotational constant B 000 eff B 3/2 = B 000 ( 1 + B 000 /Aeff ) 79 B 000 = 0. 1415105(32) cm-1 eff B 1/2 = B 000 ( 1 - B 000 /Aeff ) 81 B 000 = 0. 1406757(41) cm-1 79 A eff = -1476. 4669(48) cm-1 81 A eff = -1476. 4841(60) cm-1 Effective spin-orbit interaction constant Aeff = n 1/2 – n 3/2 low resolution emission spectroscopy A = - 1477 cm-1

r 0 -structure z. C Dm. Br S mk DI= z. Br 2 Dm.

r 0 -structure z. C Dm. Br S mk DI= z. Br 2 Dm. Br + S mk Br × G C N I = S m k zk 2 z. Br 0 = S m k zk species electronic state r. Br. C z. N r. CN Br. CN X 1 S+ 1. 789 1. 158 Br. CN+ X 2 P 1. 788(54) 1. 745(7)a 1. 103(78) 1. 195(8)a 1. 814(61) 1. 064(90) A 2 S+ unit : A a : The rs-structure determined by Rosslein et al.

Main electronic configuration (3 s)2 (1 p)4 (4 s)2 (2 p)4 : Br. CN

Main electronic configuration (3 s)2 (1 p)4 (4 s)2 (2 p)4 : Br. CN (X 1 S+) (3 s)2 (1 p)4 (4 s)2 (2 p)3 : Br. CN+ (X 2 P) 4 p (Br) – p(CN) (3 s)2 (1 p)4 (4 s)1 (2 p)4 : p (Br) (non-bonding) Br. CN+ (A 2 S+) pz (N) (non-bonding) Geometrical change is small !

A 2 S+ - m 2 S transition P 12 R 12 P 2

A 2 S+ - m 2 S transition P 12 R 12 P 2 R 2

Molecular constants (unit : cm-1) A 2 S+(000) – X 2 PW(010) transition of

Molecular constants (unit : cm-1) A 2 S+(000) – X 2 PW(010) transition of 79 Br. CN+ state m 2 S k 2 S 13410. 1135(12) 11921. 6949(21) constant A 2 S+ (000) X 2 P (010) n B 107 D g B 107 D p 0. 14117 a 0. 346 a -0. 0178 a 0. 1419339(19) 0. 3165(60) -0. 020312(27) 0. 1420853(25) 0. 3035(58) -0. 018749(46) a : Fixed to the values derived from the rotational analysis of the origin bands. Rotational constant B 010 Bk = B 010 + [ (B 010 – g/2) cos 2 b ]2/2 r Bm = B 010 - [ (B 010 – g/2) cos 2 b ]2/2 r 79 B = 0. 1420111(23) cm-1 81 B -1 010 = 0. 1412625(25) cm 010

Energy difference between m 2 S and k 2 S Energy difference : 2

Energy difference between m 2 S and k 2 S Energy difference : 2 r A 2 S+(000) 2 r = [ Aeff 2 + (2 ew 2)2 ]1/2 = nm - nk 279 r nm k 2 S = 1488. 4186(24) 281 r = 1488. 4050(30) cm-1 2 r > |Aeff| (= 1476. 47 cm-1) nk 2 r X 2 P(010) Small influence of the Renner-Teller effect on the X 2 P state of Br. CN+ m 2 S

Renner parameter e p : W – type doubling constant p = 4 B

Renner parameter e p : W – type doubling constant p = 4 B 010 ew 2/2 r state constant m 2 S k 2 S p p B 010 2 r w 2 e : Renner parameter 79 Br. CN+ 81 Br. CN+ -0. 020312(27) -0. 018749(46) -0. 020187(32) -0. 018563(52) 0. 1420111(23) 0. 1412625(25) 1488. 4186(24) 1488. 4050(30) 287. 24(20)a a : Low resolution emission spectroscopy (Fulara et al. ) 79 e 81 e = -0. 18529(27) BO 2 (X 2 P) = -0. 18512(32) CO 2+ (X 2 Pu) e = -0. 190 e = -0. 19

Wave functions for m 2 S and k 2 S sin 2 b =

Wave functions for m 2 S and k 2 S sin 2 b = ew 2/2 cos 2 b = Aeff/2 sin 2 b : cos 2 b = 0. 0040 : 0. 9959 Influence of the Renner-Teller effect on the X 2 P state of Br. CN+ is small ! Large spin-orbit interaction !

Summary 1. Near-infrared emission spectrum of the A 2 S+ - X 2 P

Summary 1. Near-infrared emission spectrum of the A 2 S+ - X 2 P transition of the Br. CN+ ion was observed by FT spectroscopy. 2. Rotational analysis of the four bands, A 2 S+ (000) - X 2 PW (000) ( W=3/2 and 1/2 ) A 2 S+ (000) - m 2 S and A 2 S+ (000) - k 2 S, was performed to determine the molecular constants. 3. The r 0 -structures of Br. CN+ were obtained and geometrical difference between Br. CN and Br. CN+ was small. 4. Renner parameter was determined to be e = -0. 185, 0. 185 and the influence of the Renner-Teller effect on X 2 P was turned out to be small due to the large spin-orbit interaction