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DIODE- AND DIFFERENCE-FREQUENCY LASER STUDIES OF ATMOSPHERIC MOLECULES IN THE NEAR- AND MID-INFRARED: H 2 O, NH 3, and NO 2 Johannes ORPHAL, Pascale CHELIN,

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Presentation on theme: "DIODE- AND DIFFERENCE-FREQUENCY LASER STUDIES OF ATMOSPHERIC MOLECULES IN THE NEAR- AND MID-INFRARED: H 2 O, NH 3, and NO 2 Johannes ORPHAL, Pascale CHELIN,"— Presentation transcript:

1 DIODE- AND DIFFERENCE-FREQUENCY LASER STUDIES OF ATMOSPHERIC MOLECULES IN THE NEAR- AND MID-INFRARED: H 2 O, NH 3, and NO 2 Johannes ORPHAL, Pascale CHELIN, Nofal IBRAHIM, and Pierre-Marie FLAUD Laboratoire Interuniversitaire des Systèmes Atmosphériques Université de Paris-12, Créteil, France

2 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Tunable diode-lasers are available in the near-infrared region: 0.7 – 2.0 m (optical telecommunication) Extremely useful for quantitative spectroscopy of atmospheric molecules (many studies in the last 5 years) Very high-resolution (less than cm -1 ) with external cavities Many photons (at least a few mW) on output High signal/noise ratio (a few 1000) in short measurement time Single wavelength, tunable over several 10 nms (a few 100 cm -1 ) A laser based on difference-frequency generation can transport these properties into the mid-infrared (3 – 5 m) This talk: applications to H 2 O, NH 3, NO 2 This talk: applications to H 2 O, NH 3, NO 2 Quantitative Spectroscopy Using IR Lasers Quantitative Spectroscopy Using IR Lasers

3 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Toptica DL-100 (Littrow configuration) External Cavity Diode-Lasers External Cavity Diode-Lasers grating forms part of the cavity linewidth 1 MHz ( cm -1 ) output power up to 30 mW spectral range: 810 – 880 nm (11360 – cm -1 ) 1535 – 1565 nm (6390 – 6515 cm -1 ) tunable range (single mode) at least GHz ( cm -1 ) relatively small beam divergence

4 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, H 2 O absorption line around 830 nm External Cavity Diode-Lasers External Cavity Diode-Lasers

5 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, White-type absorption cell L = 1 m, maximum path length 100 m, CaF 2 windows 3 MKS Baratrons Water sample Thermometer

6 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, The H 2 O band around 822 nm

7 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, R. A. Toth, J. Mol. Spectrosc., 166, (1994) J.-M. Flaud et al., J. Mol. Spectrosc., 185, (1997) P. L. Ponsardin et al., J. Mol. Spectrosc., 185, (1997) A. Lucchesini et al., Eur. Phys. J. D., 8, (2000) R. Schermaul et al, J. Mol. Spectrosc. 208, (2001) A. Ray et al., Appl. Phys. B, 79, (2004) Previous measurements of H 2 O around 822 nm Example: line intensities ( S /cm molecule -1 ) position (cm -1 )HITRAN04PonsardinSchermaulRay ! Differences between different authors exceed stated accuracy (up to 30%) need for more measurements

8 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Experimental Precautions H 2 O samples: distilled, cleaned by ultrasonic procedure Calibrating the MKS Baratron heads Validation of detector linearity using neutral density filters Linearization of the wavenumber axis: FP etalon (1 MHz) Simultaneous recording of HDO lines (in the mid-IR using a DFG laser) to validate H 2 O pressure values (assumption: natural HDO abundance); result: less than 2 % deviations Background emission of the ECDL narrow spectral filter Validate analysis software with synthetic lines

9 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Results from LISA Example 1: Self-broadening of the line at cm -1 High S/N ratio( >1000) Experimental lines well reproduced using Voigt profile Weak residuals due to Dicke narrowing

10 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Results from LISA Example 2: Air-broadening of the line at cm -1 Again: weak residuals due to Dicke narrowing (even at 200 Torr)

11 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Results from LISA Example 3: Self-broadening of 3 lines near cm -1 Note: the Dicke-narrowing also affects the baseline between the lines

12 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Line intensities Note: Straight lines (1-2 %) Up to 10 % difference between fixed and free D in the Voigt profile MEAN value (!) 15 % above HITRAN2004 Good agreement (5 %) with Ponsardin and Browell, JMS 1997 Difference can not be explained by line profile Fixed Free

13 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Self-broadeningSelf-broadening Note: Straight line (1 %) BUT: 10 % lower than HITRAN2004

14 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Air-broadeningAir-broadening Note: Straight line (< 1 %) Good agreement with HITRAN2004 (< 5 %)

15 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Conclusions for H 2 O around 822 nm 40 different H 2 O lines measured between 815 and 835 nm. Intensities in the 830 nm band 15% higher than HITRAN2004. Self-broadening coefficients 10% lower than HITRAN2004. Air-broadening coefficients in good agreement (< 5%) with HITRAN2004. Dicke-narrowing although weak, check impact on line intensities using other profiles (Galatry, Rautian,…) Perform new, independent experiments (FTS?) Strategies for H 2 O broadening in HITRAN

16 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Toptica DL-100 (Littrow configuration) External Cavity Diode-Lasers External Cavity Diode-Lasers grating as part of the cavity linewidth 1 MHz ( cm -1 ) output power up to 30 mW spectral range: 810 – 880 nm (11360 – cm -1 ) 1535 – 1565 nm (6390 – 6515 cm -1 ) tunable range (single mode) at least GHz ( cm -1 ) relatively low beam divergence

17 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Toptica DL-100 (Littrow configuration) External Cavity Diode-Lasers External Cavity Diode-Lasers output power up to 30 mW Photo-acoustic spectroscopy (PAS)

18 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Reminder: How works PAS Thanks to Prof. Th. Huet, University of Lille, France Photoacoustic effect: Collisional energy transfer Laser tuned to a molecular transition: Excited molecules Partly, non radiative de-excitation Temperature changes Pressure changes Acoustic wave Detection by microphone Photoacoustic Spectroscopy of NH 3 around 1.5 m Photoacoustic Spectroscopy of NH 3 around 1.5 m

19 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Simultaneous direct absorption measurements using a White-type multiple-pass cell Photoacoustic Spectroscopy of NH 3 around 1.5 m Photoacoustic Spectroscopy of NH 3 around 1.5 m

20 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Simultaneous direct absorption measurements using a White-type multiple-pass cell Photoacoustic Spectroscopy of NH 3 around 1.5 m Photoacoustic Spectroscopy of NH 3 around 1.5 m

21 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Photoacoustic Spectroscopy of NH 3 around 1.5 m Photoacoustic Spectroscopy of NH 3 around 1.5 m Spectral calibration using the FTS line positions of Lundsberg-Nielsen et al. (1993)

22 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Problem: The relative line intensities seem to be incorrect: Lines No. 2 and 3 should be very similar, about 60 % of the line No. 1 Check with direct absorption spectra Photoacoustic Spectroscopy of NH 3 around 1.5 m Photoacoustic Spectroscopy of NH 3 around 1.5 m 1 2 3

23 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Absorption Spectroscopy of NH 3 around 1.5 m Absorption Spectroscopy of NH 3 around 1.5 m Spectral calibration using the FTS line positions of Lundsberg-Nielsen et al. (1993)

24 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Absorption Spectroscopy of NH 3 around 1.5 m Absorption Spectroscopy of NH 3 around 1.5 m

25 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Problem: The relative line intensities seem to be incorrect: Lines No. 2 and 3 should be very similar, about 60 % of the line No. 1 The fitted Doppler widths are not equal ! Absorption Spectroscopy of NH 3 around 1.5 m Absorption Spectroscopy of NH 3 around 1.5 m Spectral calibration using the FTS line positions of Lundsberg-Nielsen et al. (1993)

26 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, New absorption spectra using FTS: Bruker IFS 120 HR Fourier spectrometer (Orsay) Absorption cell 25 cm, CaF 2 windows NH 3 pressure 30 mbar Spectral range 5950 – 7850 cm -1 Spectral resolution 0.02 cm -1 Absorption Spectroscopy of NH 3 around 1.5 m Absorption Spectroscopy of NH 3 around 1.5 m

27 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, NH 3 15 NH 3 Absorption Spectroscopy of NH 3 around 1.5 m Absorption Spectroscopy of NH 3 around 1.5 m

28 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, NH 3 15 NH 3 Line No. Lundsberg-Nielsen et al. JMS 162 (1993) This work (FTS) (*) Difference in cm (*) calibrated using the IUPAC recommended standard: H 2 O lines of Toth, accuracy (RMS) cm -1 The new NH 3 linelist is available in digital format upon request to the authors. Absorption Spectroscopy of NH 3 around 1.5 m Absorption Spectroscopy of NH 3 around 1.5 m Comparison of the NH 3 line positions (example)

29 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Chopper Wavemeter DFG DFG (Difference Frequency Generation) Laser) Mid-IR NO 2 line intensities using a DFG laser Mid IR ECDL: 30 mW nm Linewidth 1 MHz DFG µm Linewidth 1MHz Lock-in detection LabView acquisition S/N>1000 Measurement time: few minutes

30 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, ECDL: 30 mW nm Linewidth 1 MHz DFG µm Linewidth 1MHz Lock-in detection LabView acquisition S/N>1000 Measurement time: few minutes DFG DFG (Difference Frequency Generation) Laser) Mid-IR NO 2 line intensities using a DFG laser

31 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, ECDL: 30 mW nm Linewidth 1 MHz DFG µm Linewidth 1MHz Lock-in detection LabView acquisition S/N>1000 Measurement time: few minutes DFG DFG (Difference Frequency Generation) Laser) Mid-IR NO 2 line intensities using a DFG laser

32 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, P N2O = mbar II.1. Caractérisation instrumentale: spectroscopie de N 2 O. Interféromètre de Fabry Pérot, Validation avec N 2 O. Validation of the DFG using N 2 O, CH 4 and HI Validation of the DFG using N 2 O, CH 4 and HI Mid-IR NO 2 line intensities using a DFG laser

33 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, P N2O = 7, mbar II.1. Caractérisation instrumentale: spectroscopie de N 2 O. Interféromètre de Fabry Pérot, Validation avec N 2 O. Validation of the DFG using N 2 O, CH 4 and HI Validation of the DFG using N 2 O, CH 4 and HI Mid-IR NO 2 line intensities using a DFG laser RMS deviation cm -1

34 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.1. Caractérisation instrumentale: spectroscopie de N 2 O. Interféromètre de Fabry Pérot, Validation avec N 2 O. Validation of the DFG using N 2 O, CH 4 and HI Validation of the DFG using N 2 O, CH 4 and HI Mid-IR NO 2 line intensities using a DFG laser RMS deviation 0.7 %

35 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Spectre dabsorption de la bande fondamentale de HI. Bande dabsorption υ 1 Validation of the DFG using N 2 O, CH 4 and HI Validation of the DFG using N 2 O, CH 4 and HI Mid-IR NO 2 line intensities using a DFG laser R(0)

36 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Spectre dabsorption de la bande fondamentale de HI. Bande dabsorption υ 1 Validation of the DFG using N 2 O, CH 4 and HI Validation of the DFG using N 2 O, CH 4 and HI Mid-IR NO 2 line intensities using a DFG laser

37 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.2. Intensités de raies de NO 2. Motivations NO 2 concentrations determined using the VIS NO 2 concentrations determined using the VIS Mid-IR NO 2 line intensities using a DFG laser

38 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.2. Intensités de raies de NO 2. Motivations NO 2 concentrations determined using the VIS NO 2 concentrations determined using the VIS Mid-IR NO 2 line intensities using a DFG laser

39 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.2. Intensités de raies de NO 2. Motivations NO 2 concentrations determined using the VIS NO 2 concentrations determined using the VIS Mid-IR NO 2 line intensities using a DFG laser

40 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.2. Intensités de raies de NO 2. Motivations Typical mid-IR spectrum and fit (residuals × 25) Typical mid-IR spectrum and fit (residuals × 25) Mid-IR NO 2 line intensities using a DFG laser résidu x 25 υ 1 + υ 3 (υ 1 + υ 2 + υ 3 )- υ 2 P NO2 = 2 mbar

41 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.2. Intensités de raies de NO 2. Motivations Mid-IR NO 2 line intensities using a DFG laser

42 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, II.2. Intensités de raies de NO 2. Motivations Results for the cold band Results for the cold band lines measured 27 lines measured Mean deviation wrt. HITRAN2004: % ± 1.2 % Mean deviation wrt. HITRAN2004: % ± 1.2 % Results for the hot band ( ) - 2 Results for the hot band ( ) lines measured (many lines are blended) 8 lines measured (many lines are blended) Mean deviation wrt. HITRAN2004: % ± 1.2 % Mean deviation wrt. HITRAN2004: % ± 1.2 % Line positions of the hot band ( ) - 2 slightly shifted (see also Perrin et al., 1997) Line positions of the hot band ( ) - 2 slightly shifted (see also Perrin et al., 1997) Mid-IR NO 2 line intensities using a DFG laser

43 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Using ECDL for studying line intensities and shapes in the near- and mid-IR, at very high S/N and spectral resolution DFG lasers can transport these properties into the mid- infrared (3 – 5 m) and possibly at longer wavelengths H 2 O: line intensities of the 822 nm band 15 % too low H 2 O: line intensities of the 822 nm band 15 % too low NH 3 : new NIR line list recorded using FTS NH 3 : new NIR line list recorded using FTS NO 2 : very good agreement between UV and IR at 3 m NO 2 : very good agreement between UV and IR at 3 m Further studies: H 2 CO, O 3, HO 2 … Further studies: H 2 CO, O 3, HO 2 … Conclusions Conclusions

44 Quantitative Spectroscopy Using Diode- and DFG Lasers in the IR 9th International HITRAN Conference, Cambridge, June 26, Pierre-Marie Flaud (PhD, ) Nofal Ibrahim (PhD, ) Acknowledgements Acknowledgements CNRS Department Sciences Physique et Mathématiques University of Paris-12 Créteil


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