1. Application of Time-Resolved Fourier-Transform Infrared Spectroscopy to Photodissociation Dynamics Application of Time-Resolved Fourier-Transform Infrared Spectroscopy to Photodissociation Dynamics Yuan-Pern Lee, Department of Applied Chemistry and Institute of Molecular Science National Chiao Tung University, Hsinchu, Taiwan

2. OutlineOutline Introduction of step-scan FTS Emission mode – slit-jet system Photolysis of Fluoro-compound Emission mode – flow system Cl + CH 3 SH, O( 1 D) + CO Absorption mode – White cell C 6 H 5 SO 2 and its reactions Introduction of step-scan FTS Emission mode – slit-jet system Photolysis of Fluoro-compound Emission mode – flow system Cl + CH 3 SH, O( 1 D) + CO Absorption mode – White cell C 6 H 5 SO 2 and its reactions

3. The Michelson Interferometer

4. Step-scan Data Acquisition t1t2t3t4t5t6 t1t2t3t4t5t6 x7x7 x1x1 x2x2 x3x3 x4x4 x5x5 x6x6 I time

5. Experimental Setup (Emission) 10 ns / 0.1  s 0.1 / 0.25 cm -1 10 ns / 0.1  s 0.1 / 0.25 cm -1

6. Photolysis of Vinyl Chloride HCCH + HCl (4-center) C Cl h h + Cl HCCH + H C 2 H 2 Cl + H HCCH + Cl HCCCl + H 2 :CC + H 2 :CCH 2 + HCl (3-center) H H Cl H H H H H H

7. Rotational Distribution of HCl (v)

8. HCl-elimination from C 2 H 3 Cl Bimodal rotational distribution of HCl(v) high J (3-center) low J (4-center) T rot  10,000 K T rot  500 K T vib  16,000 K peaked at v' = 2 ratio 83: 17 Evidence of “kick” from vinylidene  acetylene Vibrational adiabaticity? J. Chem. Phys. 114, 160 (2001)

9. C Cl h F FH FCCCl + HF (4-center) :CCF 2 + HCl (3-center) :CCF 2 FCCF X Photolysis of CF 2 CHCl at 193 nm J. Chem. Phys. 117, 9785 (2002)

10. Configuration of twin slit jets

11. TR-FTS with Twin Slit Jets Slit-Jet

12. Comparison of rot. distribution jet theory flow REMPI

13. Photolysis of Fluorobenzene at 193 nm

14. HF Emission from C 6 H 5 F (jet) at 248 nm

15. Rotational populations of HF after photolysis of C 6 H 5 F/He ~30 mTorr at 248 nm

16. Vibrational population of HF  

17. Photolysis of C 6 H 5 F at 193 nm Nascent internal energy of HF E rot = 15  2 kJ mol -1 (17  2 kJ mol -1 ) E vib = 34  4 kJ mol -1 (37  4 kJ mol -1 ) E ava = 284 kJ mol -1 ; E trans = 96 kJ mol -1 ; E HF = 48 kJ mol -1 (54  6 kJ mol -1 ) E C6H4 = 140 kJ mol -1 (134  8 kJ mol -1 ?) Nascent internal energy of HF E rot = 15  2 kJ mol -1 (17  2 kJ mol -1 ) E vib = 34  4 kJ mol -1 (37  4 kJ mol -1 ) E ava = 284 kJ mol -1 ; E trans = 96 kJ mol -1 ; E HF = 48 kJ mol -1 (54  6 kJ mol -1 ) E C6H4 = 140 kJ mol -1 (134  8 kJ mol -1 ?)

18. Photolysis of CH 3 (C 6 H 4 )F at 193 nm

19. 109.7 kcal mol -1 91.3 kcal mol -1 14.1 kcal mol -1 12.8 kcal mol -1

20. PES for HF-elimination of o-Fluorotoluene

21. Transition States of CH 3 (C 6 H 4 )F Species R HF /Å E vib /kJ mol -1 Angle E rot (expt) /kJ mol -1 E rot (impulse) /kJ mol -1 CH 2 CHF (528 kJ) 1.281 83±9 (0.157) 8.2  (219 kJ) 1-41-43.9 CF 2 CHCl (458 kJ) 1.176 46±6 (0.100) 17.0  (199 kJ) 20±416 C 6 H 5 F (284 kJ) 1.08 34±6 (0.120) 32.8  (56 kJ) 15±414 CH 3 C 6 H 4 F (251 kJ) 1.08 ~26±5 (0.103) 27.0  (59 kJ) ~10±211

22. IR emission from C 6 H 5 F irradiation at 248 nm

23. Dynamics in Bimolecular Reactions

24. Products are not produced instantly –Needs collisions –Depends on rate coefficients Rotational quenching might be substantial –Non-negligible after 1  s Nascent vibrational populations –Less affected by quenching –Extrapolation to t = 0 might have errors Products are not produced instantly –Needs collisions –Depends on rate coefficients Rotational quenching might be substantial –Non-negligible after 1  s Nascent vibrational populations –Less affected by quenching –Extrapolation to t = 0 might have errors

25. Previous Derivation of Rot. Distrib.

26. Rotational Temperatures of HCl (v = 1) from Cl + H 2 S J. Chem. Phys. 119, 4229 (2003)

27. Temporal Profiles of HCl (v = 1, 2) Model of fitting Cl + H 2 S  HCl (v = 2) + HS k 2 Cl + H 2 S  HCl (v = 1) + HS k 1 HCl (v = 2)  HCl (v = 1) k q2 HCl (v = 1)  HCl (v = 0) k q1 Model of fitting Cl + H 2 S  HCl (v = 2) + HS k 2 Cl + H 2 S  HCl (v = 1) + HS k 1 HCl (v = 2)  HCl (v = 1) k q2 HCl (v = 1)  HCl (v = 0) k q1

28. Comparison of Cl + H 2 S and Cl +CH 3 SH Cl + H 2 SCl + CH 3 SH frfr 0.12  0.020.10  0.02 fvfv 0.33  0.070.49  0.10 H...Cl1.619 Å1.675 Å D-effectrate ~0.50little effect TS (adduct)longershort-lived J. Chem. Phys. 120, 1792 (2004)

29. Transition States of Cl + CH 3 SH

30. Dynamics of the O( 1 D) +CO reaction

31. E-V energy transfer Long-lived CO 2 * collision complex Harding/Weston.Flynn JCP 88, 3590 (1988)

32. Comparison of Literature Values on Efficiency E-V energy transfer efficiency E-V energy transfer efficiency 40 % Slanger et al. (1974) Expt. 40 % Slanger et al. (1974) Expt. 21 % Shortridge et al. (1976) Expt. 21 % Shortridge et al. (1976) Expt. 25 % Harding et al. (1988) Expt. 25 % Harding et al. (1988) Expt. 31 % Matsumi et al. (1994) Expt. 31 % Matsumi et al. (1994) Expt. 29 % Makoto et al. (1994) Expt. 29 % Makoto et al. (1994) Expt. 29 % Tully (1974) Theor. 29 % Tully (1974) Theor. 21 % Kinnersly (1979) Theor. 21 % Kinnersly (1979) Theor.

33. ( ● ) experimental work; ( ○ ) trajectory calculation; (Δ) Harding et al. ( □ ) Shortridge et al. Comparison of CO Vibrational Distribution J. P. C. 1994, 98, 12641-12645 Makoto Abe, Yousuke Inagaki, Larry L. Springsteen, Yutaka Matsumi, and Masahiro Kawasaki, Hiroto Tachikawa J. P. C. 1994, 98, 12641-12645 Makoto Abe, Yousuke Inagaki, Larry L. Springsteen, Yutaka Matsumi, Masahiro Kawasaki, Hiroto Tachikawa

34. J. P. C. 1994, 98, 12641-12645 Makoto Abe, Yousuke Inagaki, Larry L. Springsteen, Yutaka Matsumi, Masahiro Kawasaki, Hiroto Tachikawa CO Rotational Distribution

35. Infrared emission spectra of CO

36. Comparison with Abe et al.

38. Detection of Intermediates TR-FTS in absorption mode

39. Experimental Setup for TRS-Absorption

41. Absorption of Cl 2 SO irradiated at 248 nm resolution = 1.5 cm -1 ; laser fluence = 100 mJ cm -2 Cl 2 SO = 0.35, Ar = 24.4 TorrCl 2 SO = 0.35, Ar = 1.5 Torr J. Chem. Phys. 120, 3179 (2004)

42. Simulated spectrum of ClSO at 300 K - Simulated - Experiment Resolution = 0.3cm -1; A’/A”, B’/B”, C’/C” = 0.9906, 0.9993, 0.9982 a-type/b-type = 1/0.2; J max =120; temp. = 350 K

43. Photolysis of C 6 H 5 SO 2 Cl

44. C 6 H 5 SO 2 Cl irradiated at 248 nm in a static cell C 6 H 5 SO 2 Cl = ~140 mTorr after 248 nm irradiating for 2 min at 10 Hz R = 0.5 cm -1

45. Transient absorption upon photolysis of C 6 H 5 SO 2 Cl at 248 nm P : 1453.5, 1403.5, 1196.4, 1088.7 cm -1 A1 : 1278.2 cm -1 A2 : 1087.7 cm -1 S : 1361.8 cm -1 (SO 2 s-str.) Temp.= 80  C R = 2 cm -1 7 expt. ave. 0-7  s static C 6 H 5 SO 2 Cl C 6 H 5 SO 2 Cl / N 2 = 1 / 240 at P = 72 Torr

46. Photolysis of C 6 H 5 SO 2 Cl  C 6 H 5 SO 2 Photolysis of C 6 H 5 SO 2 Cl  C 6 H 5 SO 2 Reaction of C 6 H 5 with SO 2  C 6 H 5 SO 2 Reaction of C 6 H 5 with SO 2  C 6 H 5 SO 2 C 6 H 5 Cl  C 6 H 5 + Cl C 6 H 5 Br  C 6 H 5 + Br C 6 H 5 Cl  C 6 H 5 + Cl C 6 H 5 Br  C 6 H 5 + Br

47. Reaction of C 6 H 5 and SO 2 A1 : 1278.2 cm -1 ; A2 : 1087.7 cm -1 B1 : 1391.6 / 1408.6 cm -1 ; B2 : 1203.4 cm -1 C 6 H 5 SO 2 Cl / N 2 C 6 H 5 Cl / SO 2 / N 2 = 1 / 14 / 100 at P = 59 Torr C 6 H 5 Br / SO 2 / N 2 = 1 / 10 / 150 at P = 63 Torr T= 80  C R = 2 cm -1 7 expt. Ave. 0 - 7  s T = 25  C R = 4 cm -1 22 - 52  s T = 25  C R = 1.5 cm -1 8 expt. ave. 17 - 47  s

48. Possible products: C 6 H 5 SO 2 C 6 H 5 OSO C 6 H 4 SO 2 Possible products: C 6 H 5 SO 2 C 6 H 5 OSO C 6 H 4 SO 2

49. Prediction of harmonic frequencies by DFT calculation C 6 H 5 SO 2 C 6 H 5 OSOC 6 H 4 SO 2 Exp. harmonic frequencies 1014.7 (5.0) / 1014.9 (13.6)986.5 (0.2)963.6 (0.03) 1017.8 (1.4) / 1023.6 (0.6)1003.0 (0.1)1012.9 (0.9) 1044.9 (8.3) / 1031.6 (24)1022.1 (0.9)1017.9 (1.7) 1063.5 (16) / 1048.6 (21.4)1052.4 (9.8)1053.9 (9.1) 1092.2 (93) / 1071.6 (56.8)1103.4 (9.4)1146.9 (0.5)1087.7 1101.2 (7.9) / 1099.6 (7.2)1153.2 (170.9)1166.5 (328)1203.4 1181.1 (0.1) / 1185.3 (0.2)1175.9 (1.8)1193.1 (33.8) 1194.8 (1.3) / 1199.1 (2.0)1187.4 (14.0)1278.4 (0.9) 1264.1 (111) / 1226.8 (106)1216.1 (121.7)1325.9 (203)1278.2 1333.4 (0.2) / 1330.0 (0.5)1336.0 (0.2)1366.3 (20.5)1391.6 ?? 1364.4 (2.5) / 1347.6 (2.8)1364.9 (0.8)1448.1 (20.8) 1481.1 (12.2) / 1479.9 (10.8)1491.0 (2.6)1482.5 (23.3) B3P86 / P3LYP with aug-cc-pVTZB3P86 with aug-cc-pVTZB3P86 with 6- 311G** C 6 H 5 SO 2 C 6 H 5 OSO C 6 H 4 SO 2 Exp. 1044.9 (8.3) / 1031.6 (24) 1022.1 (0.9)1017.9 (1.7) 1063.5 (16) / 1048.6 (21.4) 1052.4 (9.8)1053.9 (9.1) 1092.2 (93) / 1071.6 (56.8) 1103.4 (9.4)1146.9 (0.5)1087.7 1101.2 (7.9) / 1099.6 (7.2) 1153.2 (170.9)1166.5 (328)1203.4 1181.1 (0.1) / 1185.3 (0.2) 1175.9 (1.8)1193.1 (33.8) 1194.8 (1.3) / 1199.1 (2.0) 1187.4 (14.0)1278.4 (0.9) 1264.1 (111)/ 1226.8 (106) 1216.1 (121.7)1325.9 (203)1278.2 1333.4 (0.2) / 1330.0 (0.5) 1336.0 (0.2)1366.3 (20.5)1391.6 ? 1364.4 (2.5) / 1347.6 (2.8) 1364.9 (0.8)1448.1 (20.8) 1481.1 (12) / 1479.9 (10.8) 1491.0 (2.6)1482.5 (23.3) B3P86 / P3LYP B3P86 B3P86 with aug-cc-pVTZ with aug-cc-pVTZ with 6-311G**

50. Simulated spectrum of C 6 H 5 SO 2 simulation parameters A  = 0.11579 cm -1 B  = 0.03369 cm -1 C  = 0.02645 cm -1 A/A  = 1.007 B/B  = 0.997 C/C  = 0.997 Temp. = 300K J max =130 b-type:c-type = 1 : 0.3 T 0 = 1279.3 cm -1

51. Reaction of C 6 H 5 Br + SO 2 + 248 nm Reaction of C 6 H 5 Cl + SO 2 + 248 nm C 6 H 5 + SO 2  (C 6 H 5 OSO)  C 6 H 4 OSOH  C 6 H 5 SO 2  C 6 H 5 SO 2 Br C 6 H 5 + SO 2  (C 6 H 5 OSO)  C 6 H 4 OSOH  C 6 H 5 SO 2  C 6 H 5 SO 2 Cl

52.  =4.6  10 3 s -1 3619-3586 cm -1 Bn(3700) temporal profile of C 6 H 5 Br + SO 2 at 248 nm  =4.4  10 3 s -1 Bn  =1.3  10 4 s -1 An  =3.1  10 3 s -1 Cn C 6 H 5 SO 2 C 6 H 4 OSOH C 6 H 5 SO 2 B r

53. Summary Transient absorption bands at 1278 and 1088 cm -1, observed upon photolysis of C 6 H 5 SO 2 Cl at 248 nm, are assigned as the SO 2 stretching modes of C 6 H 5 SO 2. Same bands were observed from reactions of C 6 H 5 with SO 2 using C 6 H 5 Cl and C 6 H 5 Br as precursors. Additional transient absorption bands at 1203, 1408, and 3607 cm -1, observed upon reaction of C 6 H 5 with SO 2, might be due to C 6 H 4 SOH. Kinetics for formation of C 6 H 5 SO 2 and C 6 H 4 SOH are discussed.

54. SUMMARY Applications of Time-resolved FTIR Dynamics in Photolysis 4-center molecular elimination of HF Dynamics in Bimolecular Reactions Cl + H 2 S/CH 3 SH, O( 1 D) + CO Detection of Intermediates (absorption) ClSO, ClCS, C 6 H 5 SO 2 Multiplex advantage Applications of Time-resolved FTIR Dynamics in Photolysis 4-center molecular elimination of HF Dynamics in Bimolecular Reactions Cl + H 2 S/CH 3 SH, O( 1 D) + CO Detection of Intermediates (absorption) ClSO, ClCS, C 6 H 5 SO 2 Multiplex advantage

55. Chia-Yan Wu, Li-Kang Chu Sherry Liao, Shen-Kai Yang Chia-Yan Wu, Li-Kang Chu Sherry Liao, Shen-Kai Yang Ministry of Education National Science Council IAMS, Academia Sinica Ministry of Education National Science Council IAMS, Academia Sinica