1. RECENT STUDIES OF OXYGEN- IODINE LASER KINETICS Azyazov V.N. and Pichugin S.Yu. P.N. Lebedev Physical Institute,Samara Branch, Russia Heaven M.C. Emory University, Atlanta, USA

2. Chemical OIL (COIL) Cl 2 +НО 2 -  HCl + Cl - +О 2 ( 1  ) P О2  100 Тор,   =[О 2 ( 1  )]/[O 2 ]  50 % Discharge OIL (DOIL) О 2 (Х) + е  О 2 ( 1  ) + е P О2  10 Тор,    20 % O 3 -SF 6 -N 2 O О 2 (а 1  )-O( 1 D)-I 2 (или CH 3 I) UV photolysis Photolytic OIL (PhOIL) О 3 + hv  О 2 ( 1  ) + O( 1 D) P О2  1 Тор,    90 % О2О2 + - О 2 ( 1  ), О NO 2 I 2 Nozzle Resonator О2О2

3. ENERGY LEVELS OF I, O 2, I 2, H 2 O

4. List of reactions that of importance in the DOIL and PhOIL # ProcessRate constant, cm 3 s -1 O 2 ( 1  ) formation 1 O 2 ( 3  ) + e  O 2 ( 1  ) + e EE energy exchange 2323 O 2 ( 1  ) + I( 2 P 3/2 )  O 2 ( 3  ) + I( 2 P 1/2 ) O 2 ( 3  ) + I( 2 P 1/2 )  O 2 ( 1  ) + I( 2 P 3/2 ) 7.8×10 -11 2.6×10 -11 I atoms formation 4545 I 2 (X) + O( 3 P)  IO+ I( 2 P 3/2 ) IO + O( 3 P)  O 2 ( 3  ) + I( 2 P 3/2 ) 1.4×10 -10 1.5×10 -10 I( 2 P 1/2 ) quenching 6 7 8 9 10 11 I( 2 P 1/2 ) + O 2 ( 1  )  I( 2 P 3/2 ) + O 2 ( 1  ) I( 2 P 1/2 ) + I 2 (X)  I( 2 P 3/2 ) + I 2 (X) I( 2 P 1/2 )+ O( 3 P)  I( 2 P 3/2 ) + O( 3 P) I( 2 P 1/2 )+ O 3  products I( 2 P 1/2 )+ NO 2, N 2 O 4  I( 2 P 3/2 ) + NO 2, N 2 O 4 I( 2 P 1/2 )+ N 2 O  I( 2 P 3/2 ) + N 2 O 1.1×10 -13 3.8×10 -11 ? К(Т)? O 3 formation 12 13 14 O 2 + O 2 + O( 3 P)  O 3 + O 2 O( 3 P) + O( 3 P) + O 2  O 3 + O( 3 P) O( 3 P) + O 2 + Ar  O 3 + Ar 5.9×10 -34 cm 6 /s O 3 removal 15 16 17 I( 2 P 3/2 ) + O 3  IO + O 2 O 2 ( 1  ) + O 3  O 2 + O 2 + O( 3 P) O 2 ( 1  ) + O 3  O 2 ( 1  ) + O 3 1.2  10 -12 1.5  10 -11 3.3  10 -12 IO +IO reaction 18 19 IO + IO  O 2 + 2 I( 2 P 3/2 )  IO 2 + I( 2 P 3/2 ) IO + IO + M  I 2 O 2 + M 8×10 -12 3.2×10 -11 5.6×10 -30 cm 6 /s O 2 (a 1  ) quenching 20 O 2 ( 1  ) +O( 3 P) + O 2  2O 2 + O( 3 P) ? O( 3 P) scavenge 21 O( 3 P) + NO 2  O 2 + NO9.7  10 -12

5. The low-pressure flow cell apparatus with a jet-type SOG Dependence of the I* concentration on the distance along the flow for  w =3 %, O 2 :N 2 =1:1

6. Quenching of O 2 ( 1  ) has a minimal effect on the I 2 dissociation rate Reducing [O 2 ( 1  )] by an order of magnitude caused a slight increasing of the dissociation time O2(1)O2(1) I* Testing role of O 2 ( 1  ) by addition of CO 2

7. Role of I 2 (B) in the iodine dissociation Branching fraction  B =5  10 5 s -1,  b =0.08 s -1 I 2 (A, A') + O 2 (a)  I 2 ( 1 Π 1u ) + O 2 (X)  I + I + O 2 (X), approx=100 %  I 2 (B) + M  I + I + M, < 1 % COIL active medium luminescence spectra in the visible range recorded with a resolution of 1 nm at P c = 2.3 Torr,  I2 =0.5%, N 2 :O 2 =1:1

8. Estimation of excitation probabilities from Barnault et al. measurements I*+ I 2  I+I 2 (X,v)  v - excitation probability of v-th vibrational level  m≤v≤n =  v  25  0.1  10<v  23  0.9 (0 for dashed curve ) Standard dissociation model with  v  25  0.1 can not provide observed dissociation rates in COIL medium. About 20 molecules of O 2 (a) consumed to dissociate one I 2 molecule if standard model is predominant dissociation pathway.

9. Pump-probe technique used to study OIL kinetics Monochro mator Ge Digital Oscilloscope Nd/YAG Pumped Dye Laser Delay Generator Pump Fluorescence cell I 2 +Ar Light baffles Quenching gas Excimer laser Rate of I 2 (A') quenching (R q ) depends on CO 2 partial pressure Р СО2 at P Ar =50 Torr, Р I2 =0.013 Torr and T=300 K K CO2 = 8.5  10 -13 cm 3 /s K Ar = 2.7  10 -14 cm 3 /s K O2 = 6  10 -12 cm 3 /s K I2 = 4.8  10 -11 cm 3 /s

10. N 2 O,NO 2 or O 3 Pump 193 or 248 nm Power meter 1268 nm filter Ge photo- detector O 2 ( 1  ) formation: N 2 O +193 nm  O( 1 D) + N 2 O( 1 D) + N 2 O  N 2 + O 2 ( 1  ) ? O( 3 P) + NO 2  NO + O 2 ( 1  ) ? O 3 +248 nm  O( 1 D) + O 2 ( 1  ) O 2 ( 1  )  O 2 ( 3  )+1268 nm Branching fraction for O 2 ( 1  ) from O( 1 D)+N 2 O & O( 3 P)+N 2 O Typical temporal profiles of the 1268 nm emission intensities for the N 2 O photolysis experiment (I N2O ) – P N2O =207 Torr, P Ar =407 Torr and for the O 3 photolysis experiment (I O3 )- P N2 =755 Torr, P Ar =1.3 Torr # I N2O mV I O3 mV  E 193 mJ  E 248 mJ   a 1234512345 0.15 0.14 0.11 0.35 0.33 0.51 0.33 14.4 15.8 14.2 16 11 11.2 18.4 11.2 1.03 0.94 1.03 0.97 1.05 Yield O( 1 D) + N 2 O  N 2 + O 2 ( 1  ) 100 % O( 3 P) + NO 2  NO + O 2 ( 1  ) <10 %

11. Quenching I( 2 P 1/2 ) by О( 3 Р), О 3 N 2 O + 193 нм  N 2 + O( 1 D) O( 1 D) + N 2 O  N 2 + O 2 ( 1  )  NO + NO O 3 +248 nm  O( 1 D) + O 2 ( 1  ) O( 1 D) + CO 2 (N 2 )  O( 3 P) + CO 2 (N 2 ) I 2 (X) + O( 3 P)  IO+ I( 2 P 3/2 ) IO + O( 3 P)  O 2 ( 3  ) +I( 2 P 3/2 ) I( 2 P 3/2 ) + O 2 ( 1  )  I( 2 P 1/2 ) + O 2 ( 3  ) I( 2 P 1/2 ) + O( 3 P)  I( 2 P 3/2 ) +О( 3 P) I( 2 P 1/2 ) + O 3  products I( 2 P 1/2 )  I( 2 P 3/2 )+ h ( = 1315 nm) Dashed lines are calculations at K O =1.2  10 -11 cm 3 /s K O3 =1.8  10 -12 cm 3 /s

12. Quenching I( 2 P 1/2 ) by NO 2, N 2 O 4 & N 2 O CF 3 I + h (248 nm)  CF 3 + I( 2 P 1/2 )  NO2 =2.85x10 -19 cm 2 NO 2 + h (248 nm)  O + NO  NO2 =2x10 -20 cm 2 N 2 O 4 + h (248 nm)  NO 2 + NO 2  N2O4 = 80  NO2  O+ NO+NO 2 K N2O4 = (3.7  0.5)×10 -13 cm 3 /s K NO2 = (2.9  0.3)×10 -15 cm 3 /s K N2O = (1.3  0.1)×10 -15 cm 3 /s

13. Temporal emission intensity of O 2 ( 1  ) at P O3 =2.4 Torr, P tot =773 Torr. Dashed lines are calculations at K=1.1x10 -31 cm 6 /s. NO 2 emission intensity near to 600 nm at P O3 =2.4 Torr, P N2O =2.8 Torr, P tot =762 Torr Quenching of O 2 (a 1  ) in the presence О 2 and O( 3 P) O 3 +h (248 nm)  O( 1 D) + O 2 ( 1  )  O( 3 P) + O 2 (X) O 2 ( 1  )  O 2 ( 3  )+ h (1268 nm) O( 3 P) + O 2 ( 1  ) + O 2  O( 3 P) + 2O 2

14. Conclusions Standard dissociation model with  v  25  0.1 can not provide observed dissociation rates in COIL medium. About 20 molecules of O 2 (a) consumed to dissociate one I 2 molecule if standard model is predominant dissociation pathway. The total excitation probabilities of I 2 (X,v) in reaction I* + I 2  I + I 2 (X,v>10) are  v  25  0.1 and  10<v<25  0.9 I 2 (B) and takes a minor part in iodine dissociation and O 2 (b) does not play a noticeable role in I 2 (B) formation I 2 dissociation pathway involving O 2 (b) state is not major channel

15.  Measured kinetic constants : I 2 (A) + CO 2  I 2 (X) + CO 2 (8.5  0.9)  10 -13 cm 3 /s I 2 (A) + O 2  I 2 (X) + O 2 (6.0  0.6)  10 -12 cm 3 /s I 2 (A) + I 2  I 2 (X) + I 2 (4.8  0.9)  10 -11 cm 3 /s I 2 (A) + Ar  I 2 (X) + Ar(2.7  0.3)  10 -14 cm 3 /s О 2 (b) + CO 2  О 2 (а) + CO 2 (6.1  0.5)  10 -13 cm 3 /s О 2 (b) + O 3  products(1.9  0.2)  10 -11 cm 3 /s I( 2 P 1/2 ) + O( 3 P)  I + O( 3 P) (1.2±0.1)  10 -11 cm 3 /s I( 2 P 1/2 ) + O 3  products(1.8±0.4)  10 -12 cm 3 /s I( 2 P 1/2 ) + NO 2  I + NO 2 (2.9±0.3)  10 -15 cm 3 /s I( 2 P 1/2 ) + N 2 O 4  I + N 2 O 4 (3.7±0.5)  10 -13 cm 3 /s I( 2 P 1/2 ) + N 2 O  I + N 2 O(1.3±0.1)  10 -15 cm 3 /s O 2 (a 1  ) + O( 3 P) + O 2  O( 3 P) + 2O 2 (1.1±0.2)  10 -31 cm 6 /s  Yield of O 2 (a 1  ) in reactions O( 1 D) + N 2 O  N 2 + O 2 ( 3  ) or O 2 ( 1  ) - 1±0.12 O( 3 P or 1 D) + NO 2  NО + O 2 ( 3  ) or O 2 ( 1  ) - < 0.1 Conclusions

16. O 2 (a,v=3)+I 2 (X)  O 2 (X)+2I (97) O 2 (a,v=1)+I 2 (X,v  15)  O 2 (X)+2I (102) O 2 (a,v=2)+I 2 (X,v  8)  O 2 (X)+2I (103) O 2 (b) + I 2 (X)  O 2 (X) + 2I (21) Developed I 2 dissociation model I* + I 2  I + I 2 (10<v<25) (33) I 2 (10<v<25)+O 2 (a)  O 2 (X)+I 2 (A’,A) (101) O 2 (a,v=1)+I 2 (X)  O 2 (X)+I 2 (A’) (95) O 2 (a,v=2)+I 2 (X)  O 2 (X)+I 2 (A) (96) O 2 (a)+I 2 (A’,A)  O 2 (X)+2I (25) Potential energy curves of I 2. The red and blue arrows show the excitation pathways of energy states lying bellow and above the I 2 dissociation limit, respectively. The inscriptions above arrows denote the reaction producing excitation Heidner et al. model O 2 (a)+I 2 (X)  O 2 (X)+ I 2 (20<v<45) (32) I 2 (20<v<45)+O 2 (a)  O 2 (X)+2I (34) I* + I 2  I + I 2 (25<v<45) (33)

17. Conclusions A model that involves excitation of I 2 (A’,A) by reactions O 2 (a,v=1)+I 2 (X)  O 2 (X)+I 2 (A’) (95) O 2 (a,v=2)+I 2 (X)  O 2 (X)+I 2 (A) (96) O 2 (a)+I 2 (A’,A)  O 2 (X)+2I (25) I* + I 2  I + I 2 (10<v<25) (33) I 2 (10<v<25)+O 2 (a)  O 2 (X)+I 2 (A’,A) (101) yields results that are in reasonable agreement with the flow tube experiments.