Presentation is loading. Please wait.

Presentation is loading. Please wait.

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.

Similar presentations


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 < ℃ Ge plate 1 W tunable: 760 ~870 nm 1 W 1064nm DFG radiation 55 μW 50 mm

4 Experimental Set-up (2) Temperature~ 500 ℃ 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) times enhanced from 27 ℃ to 600 ℃ R(60) 10 times enhanced from 27 ℃ to 600 ℃ R(100) 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) times enhanced from 27 ℃ to 600 ℃ R(60) 10 times enhanced from 27 ℃ to 600 ℃ R(100) 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) 31 m torr 487 °C S/N ratio : 110 R(70) 31 m torr 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) R (48) R (31) R (31) R (33) R (30) R (34) R (35) R (36) R (39) R (32) R (72)

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

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

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

23 Molecular Constants Fitting 4.3 μm 9.4 μm 10.4 μm [10 0 0, ] I,II Precise molecular constants of state By Amy-Klein et al. This work: Refine 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 ← ν0ν (92) B(00 0 1) D(00 0 1) × H(00 0 1) × L(00 0 1) × B(00 0 0) (3) D(00 0 0) × (22) H(00 0 0) × (55) L(00 0 0) × (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, (2004).

25 Molecular Constants (2) ConstantsThis Work Previous work in lab b Miller et al. c ν0ν (92) (303) (117) B(00 0 0) (3) (11) (36) D(00 0 0) × (22) (92) (186) H(00 0 0) × (55) (275) (250) L(00 0 0) × (42) (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, (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 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 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 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 level.

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


Download ppt "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."

Similar presentations


Ads by Google