LASER-INDUCED FLUORESCENCE STUDIES OF THE JET-COOLED CARBON DIOXIDE AND NITROUS OXIDE CATIONS June Mohammed A. Gharaibeh and Dennis J. Clouthier Department of Chemistry, University of Kentucky, Lexington, KY

Introduction Astronomical importance: the emission bands of CO 2 + have been found in the Martian dayglow and aurora, and in the tails of comets. Play a role in the operation of high power carbon dioxide lasers. CO 2 Plays an important role in the ionosphere, as it is the intermediate in the reaction of O + and N 2. N2O+N2O+ +

L  S  Spin orbit coupling and Renner-Teller effect in triatomic 2  systems uu A   3/2   1/2  2  1/2 2  5/2 2  3/2  2  1/ uu A

CO 2 MO diagram +     uu gg SHOMO HOMO

Splitting of the degenerate levels ( 2  ) A=0,  =0 A  0,  0 2  1/2 2  3/2  2  1/2 2  5/2 2  3/2  2  1/2  2  3/2  2  7/2  2  5/2  2  1/2 2  1/2 2  3/2  2  3/2  2  1/2 2  1/2 2  3/2 V”= V’=0 A2A2 X2X2 l =1 l =0,2 2S+1 K P K=| ±  ± l | P=| ±  ± l |=| ±  ±  ± l | Selection Rules:  K=  = 0  P=0 ~ ~

Production of jet-cooled cations Pulsed valve Ring electrodes Reheat tube Vacuum (~10 -5 torr) 50 psi of 5% CO 2 in Ar CO psi of 10% N2O in Ar N2O+N2O+ HV

Wavenumber (cm -1 ) Low resolution LIF spectrum of 12 CO 2 2  3/2 2  1/2 2  3/2 2  1/2 X 2  A 2  ~ ~ + 1

Q(1.5) Q(0.5) A 2  3/2 ← X 2  3/2 A 2  1/2 ←X 2  1/2 Rotationally-resolved spectrum Experimental Simulated ~ ~ ~ ~

Single vibronic level emission spectra of 13 CO 2 Displacement (cm -1 ) Selection Rules:  K=  = 0  P=0 +

Parameter A 2  12 COA 2  13 COX 2  13 CO  (19) (25)1265.6(12)  (14)452.32(18)499.70(75)  (36) (22)…  (2) (4) (8) A (29)-95.25(34) (35) W (53)19.64(15)26.69(34) g k 1.89(25)1.23(29)…    2.02(50)1.23(34)… x (30)-3.329(44)-9.59(36) x (36)-17.15(13)… N RMS ~ ~ ~ Vibronic parameters (cm −1 ) for the A 2  and X 2  states of 12 CO 2 and 13 CO ~ ~

Parameter A 2  12 COA 2  13 CO  (19) (25)  (14)452.32(18)  (36) (22)  (2) (4) A (29)-95.25(34) ~ ~ Checking the validity of the results Teller–Redlich product rule

       N 2 O + MO diagram SHOMO HOMO

Potential-energy curves of N 2 O + Energy R (N-NO + ) X 2  u ~ AA ~    (NO + +N) B 2  u ~

Wavenumber(cm -1 ) Low resolution LIF spectrum of N 2 O + A2A2 X 2   X 2   ~ ~ ~

A=0,  =0 A  0,  0 X2X2 2S+1 K P  2  1/2 2  5/2 2  3/2  2  1/2  2  3/2  2  7/2  2  5/2  2  1/2 2  1/2 2  3/2  2  3/2  2  1/2 2  1/2 2  3/ V”= V’=0 l =0,2 l =1 A2A2  2  2  2  l =0,2 l =1 ~ ~ Renner-Teller Analysis ( 2  ) K=| ±  ± l | P=| ±  ± l |=| ±  ±  ± l | Selection Rules:  K=  = 0

3n3n 3n113n Displacement (cm -1 ) N 2 O + Emission spectrum A2A2 X 2   X 2   ~ ~ ~

ParameterCurrent work Theory* 1 (64) 2 (40) (496.5) 3 (13) A (54)  (10) W1W1 9.25(41) N48 RMS1.53 Vibronic parameters (in cm -1 ) for the X 2  state of N 2 O + * H. Gritli, Z. Benlakhdar, G. Chambaud, and P. Rosmus, Chemical Physics 178 (1-3), 223 (1993). ~

Summary 1- Low resolution LIF spectra have been obtained for A 2  state of 12 CO 2 + and 13 CO 2 + and the A 2  state of N 2 O Emission spectra has been obtained from several vibronic levels of the A 2  state of 13 CO 2 + and the A 2  state of N 2 O Vibronic energy levels of the A 2  state of 12 CO 2 + and 13 CO 2 +, X 2  state of 13 CO 2 + and the X 2  state of N 2 O + have been satisfactorily fitted to a Renner–Teller model including spin-orbit and Fermi resonance. ~ ~ ~ ~ ~ ~ ~