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High Precision Mid-IR Spectroscopy of 12 C 16 O 2 Near 4.3 μm Speaker: Wei-Jo Ting Department of Physics, National Tsing Hua University, Hsinchu, Taiwan.

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Presentation on theme: "High Precision Mid-IR Spectroscopy of 12 C 16 O 2 Near 4.3 μm Speaker: Wei-Jo Ting Department of Physics, National Tsing Hua University, Hsinchu, Taiwan."— Presentation transcript:

1 High Precision Mid-IR Spectroscopy of 12 C 16 O 2 Near 4.3 μm Speaker: Wei-Jo Ting Department of Physics, National Tsing Hua University, Hsinchu, Taiwan June 23, 2009

2 Motivation Continue our previous study : absolute frequencies of fundamental band transitions with J up to 60 (accuracy < 30 kHz). Fewer high J frequency data in HITRAN database..

3 Experimental Set-up (1) Ti:Sapphire Nd:YAG laser MgO 2 :PPLN Temperature stability < 0.005 ℃ Ge plate 1 W tunable: 760 ~870 nm 1 W 1064nm DFG radiation 55 μW 50 mm

4 Experimental Set-up (2) Temperature~ 500 ℃ Pressure @ 31mm torr CaF 2 window InSb detector DFG Hot CO 2 cell Lock-in amplifier Lock point

5 Frequency Calibration Ti:Sapphire laser (f TiS ) Locked onto the CO 2 3rd derivative signal Optical Frequency Comb Accuracy~ 30 kHz Nd:YAG laser (f YAG ) Offset locked to iodine-stabilized Nd:YAG laser 127 I 2 R(56)32-0 a 10 hyperfine transition f TiS - f YAG =f DFG absolute frequency

6 Frequency Calibration Ti:Sapphire laser (f TiS ) Locked onto the CO 2 3rd derivative signal Optical Frequency Comb Accuracy~ 30 kHz Nd:YAG laser (f YAG ) Offset locked to iodine-stabilized Nd:YAG laser 127 I 2 R(56)32-0 a 10 hyperfine transition f TiS - f YAG =f DFG absolute frequency

7 Frequency Calibration Ti:Sapphire laser (f TiS ) Locked onto the CO 2 3rd derivative signal Optical Frequency Comb Accuracy~ 30 kHz Nd:YAG laser (f YAG ) Offset locked to an iodine-stabilized Nd:YAG laser 127 I 2 R(56)32-0 a 10 hyperfine transition f TiS - f YAG =f DFG absolute frequency

8 Frequency Calibration Ti:Sapphire laser (f TiS ) Locked onto the CO 2 3rd derivative signal Optical Frequency Comb Accuracy~ 30 kHz Nd:YAG laser (f YAG ) Offset locked to an iodine-stabilized Nd:YAG laser 127 I 2 R(56)32-0 a 10 hyperfine transition f TiS - f YAG =f DFG absolute frequency

9 Signal Enhancement (1) R(60) 10 times enhanced from 27 ℃ to 600 ℃ R(100) 30000 times enhanced from 27 ℃ to 600 ℃ R(60) 10 times enhanced from 27 ℃ to 600 ℃ R(100) 30000 times enhanced from 27 ℃ to 600 ℃ Line strength versus temperature, R(60) and R(100) Temperature ( ℃ ) Line Strength (cm -1 /(molecule × cm -2 ))

10 Signal Enhancement (1) R(60) 10 times enhanced from 27 ℃ to 600 ℃ R(100) 30000 times enhanced from 27 ℃ to 600 ℃ R(60) 10 times enhanced from 27 ℃ to 600 ℃ R(100) 30000 times enhanced from 27 ℃ to 600 ℃ Quartz glass tube Total Cell length: 60 cm Nickel-Chromium wire heater wind over the cell Quartz glass tube Total Cell length: 60 cm Nickel-Chromium wire heater wind over the cell Line strength versus temperature, R(60) and R(100) Temperature ( ℃ ) Line Strength (cm -1 /(molecule × cm -2 ))

11 Signal Enhancement (2) 1 st derivative signal Doppler width S: line strength T: temperature 1 st derivative signal strength of the Doppler broadened profile versus temperature Prediction Experimental results agree with predictions.

12 Typical Spectrum R(70) Pressure @ 31 m torr Temperature @ 487 °C S/N ratio : 110 R(70) Pressure @ 31 m torr Temperature @ 487 °C S/N ratio : 110

13 Uncertainty

14 OFC 5 kHz

15 Uncertainty OFC 5 kHz Iodine stabilized Nd:YAG laser 4 kHz

16 Uncertainty OFC 5 kHz Iodine stabilized Nd:YAG laser 4 kHz Nd:YAG laser offset locking 30 kHz

17 Uncertainty OFC 5 kHz Iodine stabilized Nd:YAG laser 4 kHz Nd:YAG laser offset locking 30 kHz Ti:sapphire laser locking 33 kHz

18 Uncertainty OFC 5 kHz Iodine stabilized Nd:YAG laser 4 kHz Nd:YAG laser offset locking 30 kHz Ti:sapphire laser locking 33 kHz The worst case, uncertainty = 72 kHz

19 Observed Transitions Transition Measured Frequency (kHz) Prediction from our previous laboratory data Prediction from HITRAN04 Frequency (kHz)Difference (kHz) Frequency (kHz)Difference (kHz) R6471 546 328 918 (48)71 546 328 8738171 546 328 9171 R6671 568 188 557 (31)71 568 188 42213571 568 187 984572 R6871 589 286 873 (31)71 589 286 60327171 589 285 4291 444 R7071 609 623 152 (33)71 609 622 75839471 609 620 5912 561 R7271 629 196 831 (30)71 629 196 26956271 629 192 8423 989 R7871 683 336 284 (34)71 683 334 8081 47671 683 325 40610 877 R8271 715 605 364 (35)71 715 602 7662 59871 715 587 09218 271 R8471 730 590 975 (36)71 730 587 6153 36071 730 567 96123 014 R8671 744 809 909 (39)71 744 805 5804 32971 744 781 30128 608 R8871 758 261 568 (32)71 758 256 0655 50371 758 226 45435 114 R9071 770 945 409 (72)71 770 938 4726 93771 770 902 75842 651

20 Molecular Constants Fitting 4.3 μm 9.4 μm 10.4 μm 00 0 0 00 0 1 [10 0 0, 02 0 0] I,II

21 Molecular Constants Fitting 4.3 μm 9.4 μm 10.4 μm 00 0 0 00 0 1 [10 0 0, 02 0 0] I,II Precise molecular constants of 00 0 1 state By Amy-Klein et al.

22 Molecular Constants Fitting 4.3 μm 9.4 μm 10.4 μm 00 0 0 00 0 1 [10 0 0, 02 0 0] I,II Precise molecular constants of 00 0 1 state By Amy-Klein et al. This work: Refine 00 0 0 state

23 Molecular Constants Fitting 4.3 μm 9.4 μm 10.4 μm 00 0 0 00 0 1 [10 0 0, 02 0 0] I,II Precise molecular constants of 00 0 1 state By Amy-Klein et al. This work: Refine 00 0 0 state Fitting formula: F(J) is rotational energy F v (J) = B v J(J +1)−D v J 2 (J +1) 2 +H v J 3 (J +1) 3 +L v J 4 (J +1) 4 +· · ·

24 Molecular Constants (1) ConstantsThis Work Amy et.al. b 00 0 1←00 0 0 ν0ν0 2349.142 788 683 (92) B(00 0 1)0.387 141 391 966 D(00 0 1) ×10 7 1.330 275 6 H(00 0 1) ×10 13 0.152 7 L(00 0 1) ×10 19 2.30 B(00 0 0)0.390 218 955 5 (3) D(00 0 0) ×10 7 1.333 799 4 (22) H(00 0 0) ×10 13 0.141 87 (55) L(00 0 0) ×10 19 -2.450 (42) a. All values in cm −1. 1 σ uncertainty given in the last digit is given in parentheses. b. A. Amy-Klein, H. Vigue, C. Chardonnet, J. Mol. Spectros. 228, 206-212 (2004).

25 Molecular Constants (2) ConstantsThis Work Previous work in lab b Miller et al. c ν0ν0 2349.142 788 683 (92) 2349.142 787 992 (303) 2349.142 683 4 (117) B(00 0 0) 0.390 218 955 5 (3) 0.390 218 954 8 (11) 0.390 218 949 (36) D(00 0 0) ×10 7 1.333 799 4 (22) 1.333 785 9 (92) 1.334 088 (186) H(00 0 0) ×10 13 0.141 87 (55) 0.134 79 (275) 0.191 8 (250) L(00 0 0) ×10 19 -2.450 (42) -1.135 (257)─ The accuracy of molecular constants have been improved 3 times. a. All values in cm −1. 1 σ uncertainty given in the last digit is given in parentheses. b. Previous study from our laboratory in fundamental band transitions with J < 60 c. C. E. Miller et al., J. Mol. Spectrosc. 228, 329-354 (2004).

26 Summary Heating CO 2 to ~ 500 ℃ to enhance the line strength of J > 60 transitions. The absolute frequencies of 10 R-branch transitions (J = 66, 68, 70, 72, 78, 82, 84, 86, 88, 90) with uncertainty < 72 kHz. Combining with our previous measurements to refine the molecular constants of the ground vibrational level and the vibrational energy of 00 0 1 level.

27 Summary Heating CO 2 to ~ 500 ℃ to enhance the line strength of J > 60 transitions. The absolute frequencies of 10 R-branch transitions (J = 66, 68, 70, 72, 78, 82, 84, 86, 88, 90) with uncertainty < 72 kHz. Combining with our previous measurements to refine the molecular constants of the ground vibrational level and the vibrational energy of 00 0 1 level.

28 Summary Heating CO 2 to ~ 500 ℃ to enhance the line strength of J > 60 transitions. The absolute frequencies of 10 R-branch transitions (J = 66, 68, 70, 72, 78, 82, 84, 86, 88, 90) with uncertainty < 72 kHz. Combining with our previous measurements to refine the molecular constants of the ground vibrational level and the vibrational energy of 00 0 1 level.

29 Summary Heating CO 2 to ~ 500 ℃ to enhance the line strength of J > 60 transitions. The absolute frequencies of 10 R-branch transitions (J = 66, 68, 70, 72, 78, 82, 84, 86, 88, 90) with uncertainty < 72 kHz. Combining with our previous measurements to refine the molecular constants of the ground vibrational level and the vibrational energy of 00 0 1 level.

30 Future Works 01 1 1← 01 1 0 band Hot band transitions 30 times weaker. Increase DFG power. Heating CO 2 gas, increase population. Molecular const. fitting. 01 1 1← 01 1 0 band Hot band transitions 30 times weaker. Increase DFG power. Heating CO 2 gas, increase population. Molecular const. fitting.

31 Acknowledgement DFG group: Chieh-Hsing Chung, Pei-Ling Luo OFC group: Hshan-Chen Chen, Dr. Yu-Hung Lien Professor Jow-Tsong Shy $$ NSC & MOE of Taiwan

32 Thank you!


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