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1. Databases of Infrared Molecular Parameters for Astronomy 0.7 to 1000 μm (14000 to 10 cm -1 ) Linda R. Brown Jet Propulsion Laboratory California Institute.

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Presentation on theme: "1. Databases of Infrared Molecular Parameters for Astronomy 0.7 to 1000 μm (14000 to 10 cm -1 ) Linda R. Brown Jet Propulsion Laboratory California Institute."— Presentation transcript:

1 1. Databases of Infrared Molecular Parameters for Astronomy 0.7 to 1000 μm (14000 to 10 cm -1 ) Linda R. Brown Jet Propulsion Laboratory California Institute of Technology Pasadena, CA 91109 linda.brown@jpl.nasa.gov The research at the Jet Propulsion Laboratory (JPL), California Institute of Technology was performed under contracts with the National Aeronautics and Space Administration.

2 2 ASTRONOMICAL REMOTE SENSING

3 3 Basic transition line parameters: ● Line position (or center frequency) ● Line intensity @ 296 K ● Lower state energy (for temperature dependence) ● Vibrational - rotational quantum assignment Line shape parameters (Voigt) ● Pressure-broadened widths & temperature depend. ● Pressure-induced frequency shifts ● Self-broadened widths Line mixing (limited to CO 2 ; no temp. depend) (Other line shapes: none) ● Continua: collision-induced absorption (CIA) (given as cross section files)

4 4 Current Public Databases (via Web) Database Websites ( http://) Region cm -1 Num of Species Num of Transitions HITRAN 2004 cfa - www.harvard.edu (/hitran) terrestrial moleculeswww.harvard.edu 0.0 to 25233 37 1,734,469 GEISA 2003 ara.lmd.polytechnique.fr molecules planetary  terrestrial 0.0 to 35877 42 (98 iso) 1,668,371 JPL 2005 spec.jpl.nasa.gov spec.jpl.nasa.gov molecules,radicals,atoms astrophysics  terrestrial 0.0 to 100. (1314.) (340) 2,644,111 CMSD 2005 (Cologne) www.ph1.uni-koeln.de www.ph1.uni-koeln.de molecules,radicals,atoms astrophysics 0. to 300. (1134.) (300) 2 M?

5 5 Can’t find your molecule? Try semi-public customized collections DatabaseswebsitesRegion cm -1. Number of species Number of transitions PNNL Air pollution nwir.pnl.gov 600-6000 336 Cross sections only ($200) VPL Astrobiology vpl.ipac.caltech.edu vpl.ipac.caltech.edu /spectra/ 0.000001 –22000 ++ 62PNNL, HITRAN, ( team only) CDSD (CO 2 ) www.iao.ru www.iao.ru ftp://ftp.iao.ru/pub/ 0 – 70001 (CO 2 ) at 296K, 1000K Predictions based on modeled data custom SAO, HITEMP, ATMOS ….. Infrared - astronomy NONE 10 to 14000

6 6 File Structure of HITRAN Compilation (Java HAWKS) Software and Documentation Line- by-line Molecule- by-molecule IR Cross- sections Aerosol Refractive Indices HITRAN (line-transition parameters) UV Global Data Files, Tables, and References Line Coupling Supplemental Cross- sections Alternate CO 2 data Level 1 Level 2 Data Level 3

7 7 A water transition in 2004 HITRAN: 11 139.782604 3.822E-19 1.168E+00.0659.4228 446.69660.590.001970 0 0 0 0 0 0 7 1 7 6 0 6 555243332168510224* 15.0 13.0 Parameter Field size Definition MolI2Molecule number IsoI1Isotope number (1 = most abundant, 2 = 2nd most abundant,..) ν if F12.6Transition position in vacuum [cm -1 ] S if E10.3Intensity [cm -1 /(molecule∙cm -2 ) @ 296K] A if E10.3Einstein A-coefficient [s -1 ] γ air F5.4Air-broadened half-width (HWHM) [cm -1 /atm @ 296K] γ self F5.4Self-broadened half-width (HWHM) [cm -1 /atm @ 296K] E″F10.4Lower-state energy [cm -1 ] n air F4.2Temperature-dependence coefficient of air width δ air F8.6Air pressure-induced shift [cm -1 /atm @ 296K] v′, v″2A15Upper and Lower “global” quantum numbers q′, q″2A15Upper and Lower “local” quantum numbers ierr6I1Uncertainty indices for ν if, S if, γ air, γ self, n air, δ air iref6I2Reference pointers for ν if, S if, γ air, γ self, n air, δ air * A1Flag for line-coupling algorithm (line mixing) g′, g″2F7.1Upper and Lower statistical weights > 4 good < 3 bad 0 = old (1986)

8 8 CDMS main page "www.cdms.de"

9 9 Properties of the CDMS Catalog  (Mostly) rotational transitions of species for astrophysics and astrochemistry  Molecules detected or detectable in inter/circumstellar medium  Emphasis on Submillimeter and TeraHertz regions  Predictions based on modeling experimental frequencies via Hamiltonians  Separate entries for rarer isotopomers or excited vibrational states (1-1)  Recent entries include – light hydrides and deuterated species: HD 2 +, NH, ND, CH 2 D +, NH 2 D, NHD 2, ND 3 – molecules in excited vibrational states: HCN, HNC, HC 3 N, HC 5 N, CS, SiO – complex species: ethylene glycol  Format identical to that of JPL catalog Holger Muller: private communication  > 300 entries as of April 2005

10 10 CDMS: SELECTED ENTRIES out of 300 species CDMS: SELECTED ENTRIES out of 300 species

11 11 MASTER: Millimeterwave Acquisitions for Stratospheric/Tropospheric Exchange Research Target molecules HOCL HOBr COF 2 H 2 O 2 HO 2 H 2 CO OCS SO 2 NO 2 HCN H2O O3 HNO3 O 2 N2O HCl CO CH3Cl ClO BrO + Interfering species Initial Source of Line Parameters Positions: JPL (almost always) Intensities: JPL or HITRAN or new calculations line broadening: literature or new measurements or HITRAN line shift: literature or new measurements

12 12 Line-by-line parameters should be COMPLETE and ACCURATE (ENOUGH) ACCURACIES REQUIRED FOR MANY APPLICATIONS ν Positions & δ pressure-induced shifts: 0.000001 - 1.0 cm -1 S Line intensities:1 to 10% E″ Lower states energies:  ½% γ Pressure-broadening widths: 1 to 20 % η Temperature dependence of widths:10 to 40%

13 13 METHODS TO OBTAIN SPECTROSCOPIC PARAMETERS ● Calculations based on successful theoretical modeling (good for positions and intensities, but not line shapes) ● Predictions based on limited data and/or poorer theoretical modeling (warning: extrapolations very poor ! ) ● Empirical data retrieved line-by-line with some known assignments (warning: no weak lines, larger uncertainties ! ) ● Absorption cross sections from lab spectra, sometimes at different temperatures (for unresolved heavy species and continua)

14 14 Near-IR (0.7 – 2.5 μm) Parameters for earth SPECIES (HITRAN#) GENERAL COMMENT STATUS OF HITRAN 2000/04 CO (5)BEST CASE Complete Better intensities and broadening available N 2 O (4)BEST CASE Almost complete ( a few bands missing ) CO 2 (2) GOOD Better accuracies needed; line shape?? Almost complete intensities and positions often inaccurate O 2 (7) FAIR Models good; too much scatter in lab measurements; line shape?? Almost complete intensities and pressure broadening uncertain H 2 O (1) FAIR Hamiltonian models fail in NIR; empirical linelists available Incomplete weak lines missing; some better accuracies needed O 3 (3) FAIR Theory may work well enough; some measurements exists Incomplete atmospheric bands missing at 2.2 μm CH 4 (6)WORST CASE No Models for NIR; very few measurements available Incomplete Missing bands: Few assignments (no E″)

15 15 Near-IR Methane Positions and Intensities: Difficult to model because energy levels perturb each other. Triacontad: intractable: Cross sections or empirical linelist with 1% assignments. Icosad: almost intractable, but one strong band being studied. Tetradecad: region largely unassigned; no public prediction. Empirical linelist has strongest lines. Octad: poorer prediction overwritten by some empirical results for main isotope. Pentad fundamentals and overtones modeled in 3 isotopes; Hot bands intensities are estimated. Dyad and CH 3 D fundamentals good. Hot bands intensities modeled to 8%. GS predicted using measured frequencies. Intensities are uncertain and not validated! cm -1

16 16 Far-IR CH 4 Intensities for ground state transitions in HITRAN and GEISA low by 16%? HITRAN intensities for Far IR set by one “indirect method”, (calc.) [Hilico et al., J Mol Spec, 122, 381(1987)] with claim of accuracy of ± 30%. Cassam-Chenai, [JQSRT, 82,251(2003)] predicts ab initio Q branch based on Stark measurements [Ozier et al. Phys Rev Lett, 27,1329, (1971)]. The intensities are 16% higher than HITRAN values. Lab data (left) confirms a higher value for R branch manifolds. Lab Spectra of Far-IR CH4 (Wishnow) hitran fit from Orton

17 17 HITRAN 2004 Far-IR Water Positions (frequencies) well-studied

18 18 H 2 O Line Intensities All isotopologues important but not validated

19 19 Warnng! Warning! Far-IR Water Intensities are not measured Isotope Intensity accuracy and source 11 139.782604 3.822E-19 1.168E+00.0659.4228 446.69660.590.001970 0 0 0 0 0 0 7 1 7 6 0 6 55524333216851 224 15.0 13.0 13 139.997467 1.344E-22 6.538E-01.0919.4389 275.13050.690.004310 0 0 0 0 0 0 5 2 4 4 1 3 50524334226851 224 66.0 54.0 15 140.235360 8.173E-27 1.485E-01.0668.3300 801.35910.490.000000 0 0 0 0 0 0 9 4 6 8 4 5 50554032227 5 2 0 114.0 102.0 14 140.252640 1.725E-24 1.225E-01.0648.3080 942.53220.490.000000 0 0 0 0 0 0 9 5 5 8 5 4 405540 02227 5 2 0 114.0 102.0 12 140.709305 1.269E-24 7.733E-01.0643.2600 1990.85690.41-.010400 0 0 0 0 0 0 11 6 5 11 5 6 40324334222951 2 8 69.0 69.0

20 20 Pressure-broadened Widths ( HWHM ) are independent of vibration in some molecules. Coefficients for these widths temperature dependence also are independent of vibration. Pressured-induced frequency shifts depend on vibration (or position): larger magnitude in Near-IR Pressure Broadening 1-0 2-03-0 1-0 2-03-0

21 21 Variation of widths by vibrational quanta Methods a. Predict from the Complex Robert-Bonamy equations. b. Estimate widths vs quanta by applying the expected theoretical vibrational dependence to empirical widths at different wavelengths. Left: The estimation method is applied to air-broadened widths of H 2 O. □ HITRAN 2000 widths ▲Measured widths

22 22 Self-broadened CH 4 widths in near-IR bands Self-broadened CH 4 widths in near-IR bands Widths vary as a function of quanta and band. ν 1 +ν 4 at 4220 cm -1 : Widths like those of a 3-fold degenerate (F2) fundamental. These widths are within 4% of ν 3 values (at 3020 cm -1 ) and other bands with a 3- fold vibrational symmetry (F2). ν 3 +ν 4 at 4310 cm -1 : 9-fold degenerate band: variation of widths at each J is much greater. ν 2 +ν 3 at 4530 cm -1 : 6-fold degenerate band: some variation of widths at each J. Predoi-Cross et al. Multispectrum analysis of 12 CH 4 from 4100 to 4635 cm- 1 : 1. self-broadening coefficients (widths and shifts) – in press J. Mol. Spectrosc.

23 23 Line mixing (line coupling) in water u Eight laboratory spectra of water at 6 μm fitted together in order to retrieve the line positions, intensities and line shape coefficients. u The maximum pressure of hydrogen is 1.3 bar at 296 K. Top: observed-calculated residuals with line mixing Middle: observed-calculated residuals without line mixing Bottom: H 2 -Broadened H 2 O spectra of two pairs of P and R branch transitions at 1539.5 and 1653 cm -1 in the ν 2 band

24 24 Line shape study of pure CO (2 – band) Residuals differences between observed and synthetic spectra are offset by -0.1 and -0.2 (Brault et al. 2003). sdVoigt: speed-dependent Voigt profile with line mixing. sVoigt : speed-dependent “ “ without line mixing. Line shape study of pure CO (2 – band) Residuals differences between observed and synthetic spectra are offset by -0.1 and -0.2 (Brault et al. 2003). sdVoigt: speed-dependent Voigt profile with line mixing. sVoigt : speed-dependent “ “ without line mixing.

25 25 Line mixing observed in CO 2 in P and R branches Top: observed-calculated differences between observed and synthetic spectra for 8 lab scans without line mixing Middle: observed-calculated residuals with line mixing between P and R branch lines Bottom: Eight lab spectra of self- Broadened CO 2 in the near –IR. Resolution: 0.011 cm -1. Signal to noise: 2000:1. Max. pressure: 1.3 bar (at 296K).

26 26 Models for Collision-Induced Continua u http://www.astro.ku.dk/~aborysow/programs/ http://www.astro.ku.dk/~aborysow/programs/ A. Borysow, L. Frommhold calculate collision-induced spectra at different temperatures and then form model spectra of cross sections. u Very useful models and software available for generating synthetic spectra H 2 -H 2, H 2 -He, H 2 -CH 4, H 2 -Ar, N 2 -N 2, CH 4 -CH 4, N 2 -CH 4, CH 4 -Ar, CO 2 -CO 2

27 27 Low temperature spectrum of methane absorption coefficient= -ln(transmission)/(density^2 * path) First observation of R(3)-R(7) lines measurements at 0.24 and 0.06 cm-1 spectral resolution Centrifugal distortion dipole lines superposed on collision-induced spectrum. Dashed line: CH 4 Collision-Induced Absorption (CIA) from A. Borysow. Wishnow, Leung, Gush, Rev. Sci. Inst., 70, 23 (1999)

28 28 CONCLUSIONS u No public infrared database tailored for astronomy u Astronomers use their own private (undocumented) collections u Basic molecular parameters (positions, intensities) available for dozens, not hundreds, of species u Near – IR: parameters missing and inaccurate u Far-IR Insufficient attention to line-by-line intensities u Pressure broadening coefficients needed (models and meas.) u CIA models need to be validated.


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