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High Precision Mid-IR Spectroscopy of 12 C 16 O 2 [10 0 1,02 0 1] I ← 00 0 0 Band Near 2.7 µm Jow-Tsong Shy Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
![High Precision Mid-IR Spectroscopy of 12 C 16 O 2 [10 0 1,02 0 1] I ← Band Near 2.7 µm Jow-Tsong Shy Department of Physics, National Tsing Hua University, Hsinchu, Taiwan](http://images.slideplayer.com./29/9430622/slides/slide_1.jpg "High Precision Mid-IR Spectroscopy of 12 C 16 O 2 [10 0 1,02 0 1] I ← Band Near 2.7 µm Jow-Tsong Shy Department of Physics, National Tsing Hua University, Hsinchu, Taiwan")
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Motivation and Goal [10 0 1,02 0 1] I ← 00 0 0 and [10 0 1,02 0 1] II ← 00 0 0 bands near 2.7 µm are two important absorption bands in atmosphere Urban’s group has made heterodyne frequency measurements for 9 transitions with an accuracy of 600 kHz in 1991. Our goal is to provide more accurate measurements
![Motivation and Goal [10 0 1,02 0 1] I ← and [10 0 1,02 0 1] II ← bands near 2.7 µm are two important absorption bands in atmosphere Urban’s group has made heterodyne frequency measurements for 9 transitions with an accuracy of 600 kHz in 1991.](http://images.slideplayer.com./29/9430622/slides/slide_2.jpg "Our goal is to provide more accurate measurements.")
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Experimental Set-up
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Experimental Scheme
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Ti:sapphire Laser Side Fringe Locking to a Stable Cavity Frequency stability: 10 kHz; Frequency drift <100 kHz/hr
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Offset Locking of Nd:YAG Laser U. Shunemann et al., Rev. Sci. Instrum. 70, 242 (1999)
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Saturated 4.3 μm Fluorescence
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Longitudinal Fluorescence Cell Used in frequency stabilization of CO 2 laser previously
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Direct Detection vs. Fluorescence Detection Direct Detection Fluorescence Detection
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Advantages of Saturated Fluorescence Detection Zero background Higher S/N No interference fringes
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Second Harmonic Demodulated Spectrum P = 20 mTorr FWHM = 1.5 MHz
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Urban’s Spectrum
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Uncertainty OFC 5 kHz Iodine stabilized of Nd:YAG laser 10 kHz Nd:YAG laser offset locking 10kHz Ti:sapphire laser locking 10 kHz Fitting error 5 kHz Uncertainty 40 kHz
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Observed Transitions – P lines
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Observed Transitions – R lines 19 transitions measured to 40 kHz accuracy
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Molecular Constants
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Molecular Constants Comparison
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Comparison between observed and calculated frequencies Standard deviation = 46 kHz
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Summary 19 transitions have been measured to an accuracy of 40 kHz Accurate molecular constants of the [10 0 1,02 0 1] I vibrational level have been determined
![Summary 19 transitions have been measured to an accuracy of 40 kHz Accurate molecular constants of the [10 0 1,02 0 1] I vibrational level have been determined](http://images.slideplayer.com./29/9430622/slides/slide_19.jpg "Summary 19 transitions have been measured to an accuracy of 40 kHz Accurate molecular constants of the [10 0 1,02 0 1] I vibrational level have been determined")
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Future Works Improve the collection efficiency of the longitudinal florescence cell (X 10) More measurements on [10 0 1,02 0 1] I ← 00 0 0 band New measurements on [10 0 1,02 0 1] II ← 00 0 0 band
![Future Works Improve the collection efficiency of the longitudinal florescence cell (X 10) More measurements on [10 0 1,02 0 1] I ← band New measurements on [10 0 1,02 0 1] II ← band](http://images.slideplayer.com./29/9430622/slides/slide_20.jpg "Future Works Improve the collection efficiency of the longitudinal florescence cell (X 10) More measurements on [10 0 1,02 0 1] I ← band New measurements on [10 0 1,02 0 1] II ← band")
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Acknowledgement Chun-Chieh Liao Kuo-Yu Wu Yu-Hung Lien Che-Chung Chou $$ NSC & MOE of Taiwan DFG and OFC systems Carry out all measurements Molecular constants fitting
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