MK10 HCl Overtone Lineshapes 1

DETERMINATION OF PRESSURE BROADENING AND SHIFTS FOR THE FIRST OVERTONE

2←0 OF HCL

Brennan M. Coffey, Brian J. Drouin, Timothy J. Crawford

Jet Propulsion Laboratory, California Institute of Technology

6/16/2014

MK10 HCl Overtone Lineshapes 2

Motivation• Textbook case

– but precision is not up to modern standards– Last Investigation into the line centers of HCl in the MIR was done by

Guelachvili Opt. Comm. 19(1) 150-154, 1976 line positions to ~2x10-4 cm-1

• Laboratory calibration– Wavenumber calibration for 6000 cm-1 region– Dual scan experiment has allowed transfer of CH4 standard to HCl– Positions may be improved to ~1x10-5 cm-1

• No (bandwide) self broadening or self shift parameters – TCCON calibration, common calibration for networked measurement system– Remote sensing for Venusian / Jovian / Saturnian chemistry

• LabFit exercise– Multispectrum lineshape fitting

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MK10 HCl Overtone Lineshapes 3

Band Selectionhttp://hitran.iao.ru/survey/spectr

4800 5200 5600 6000 cm -1

Pubchemcommons.wikimedia.orghalo.wikia.com

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MK10 HCl Overtone Lineshapes 4

TCCON network

• The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier Transform Spectrometers that record direct solar spectra in the near-infrared. From these spectra, accurate and precise column-averaged abundances of atmospheric constituents including CO2, CH4, N2O, HF, CO, H2O, and HDO, are retrieved.

• Calibrations are performed with sealed 10 cm 5mb HCl cells inside each interferometer

• Hase, F., B.J. Drouin, C.M. Roehl, G.C. Toon, P.O. Wennberg, D. Wunch, T. Blumenstock, F. Desmet, D.G. Feist, P. Heikkinen, M. De Maziere, M. Rettinger, J. Robinson, M. Schneider, V. Sherlock, R. Sussmann, Y. Te, T. Warneke, C. Weinzierl, Calibration of sealed HCl cells used for TCCON instrumental line shape monitoring, Atmos. Meas. Tech. 6(12), 3527-3537, 2013.

• ‘Narrowing’ effect is evident in Hase et al.

http://www.tccon.caltech.edu/site-locations/index.htmlhttps://tccon-wiki.caltech.edu/

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MK10 HCl Overtone Lineshapes 5

Remote Sensing of HCl

Venus, solar occultation spectra, http://venus.aeronomie.be/en/soir/hcl.htm

Goto et al.Earth Science:HALOE, ACE, MLS, Odin, ATMOSMk IV, FIRS-2, SLS, (ALIAS in-situ)

Also astronomy with: Spitzer, ISO, ATMOS, Odin, Herschel6/16/2014

MK10 HCl Overtone Lineshapes 6

IFS-125HR

Bruker IFS-125HR at JPL▪ The entire FTS enclousure evacuated to ~10 mTorr▪ Maximum resolution, 0.0011 cm-1

▪ Detectors and beamsplitters covering 20 - 15800 cm-1

▪ Gas handling system with a 6″ Varian Turbo pump▪ MKS Baratron pressure gauges up to 6.5 bar▪ Hart Scientific PRT temperature sensors

Various absorption gas cells▪ Multipass White cell of (variable path length up to 32.5 m)▪ Cryogenic cell (0.2 m long, developed by Dr. Arlan Mantz) ▪ Various single pass custom cells (from 2 cm to 26.5 cm)▪ Very long path multipass White cell (~200 m) on the way

Pressure scans in a joint

tandem cell at 8 different pressures

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MK10 HCl Overtone Lineshapes 7

Experimental• Two cells were used• Long Path length (3.84 m)• Short Path length (0.0614 m and 0.1526 m)

(This goes inside the FTS)6/16/2014

MK10 HCl Overtone Lineshapes 8

Calibration strategy• Recent improvements in the metrology of CH4 and C2H2 have made the

desired precision and accuracy attainable• Absolute positions were determined with femtosecond laser spectroscopy

Zolot, 2013

σ (MHz) σ (cm-1)

2.3 7.6E-05

1.0 3.3E-05

1.7 5.6E-05

2.5 8.3E-05

2.4 8.0E-05

1.2 4.0E-05

7.8 2.6E-04

1.3 4.3E-05

0.5 1.6E-05

1.2 4.0E-05

1.5 5.0E-05

0.8 2.6E-05

… …Zolot et al. JQSRT 118 (2013) 26-39

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MK10 HCl Overtone Lineshapes 9

Position• Algorithm Information

– Code in Matlab was written to analyze the spectra for line centers– Thresholding based on a ratio of intensity at the base of the peak and intensity at the

peak was used as filtering criteria• <5% of max intensity was not considered a peak

– Peak picker uses zero filling, apodization, then spline interpolation between the bottom 3 points

– Peak minimum finder based on 5 smoothing points and first and second derivative tests

Position (cm-1)

Resi

dual

s (c

m-1

)

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MK10 HCl Overtone Lineshapes 10

Line CentersNumber Matched Match Threshold Standard Deviation Cal Factor

46 0.00221 0.00007009 1.00000093

40 0.00057 0.00003566 1.00000010

20 0.00012 0.00001120 1.00000003

8 0.00010 0.00000819 1.00000009

• Matched values to the Zolot lines, goal was to improve the calibration error to be <2x10-4 cm-1

• We can get 1x10-5 cm-1, sufficient precision and accuracy for use in OCO spectral analyses

• Precision was verified with quantum mechanical prediction software and had an RMS of ~7x10-6 cm-1

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MK10 HCl Overtone Lineshapes 11

Pressure Broadening• 1st Pressure broadening

and pressure shifts for entire v = 2-0 band

• Spectra taken in a dual chamber cell were used with CH4 in one chamber as the calibrant and HCl in the other

• Pressures investigated were 10,15, 20, 25, 30, 40, 50 and 60 Torr

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MK10 HCl Overtone Lineshapes 12

Spectral Fitting no constraints• Full Physics fits with LabFit to get pressure broadening and pressure shift

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MK10 HCl Overtone Lineshapes 13

Fitting Spectra with constraintsIntensities with Honl-London Factors, exp(hv/kT), positions with B0,B2, D0,D2, H0, H2

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MK10 HCl Overtone Lineshapes 14

Linestrength – HITRAN• On average 2.6%

higher than HITRAN

• Both intensity and pressure broadening are consistently higher than HITRAN

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MK10 HCl Overtone Lineshapes 15

Isotopologues Comparison – Self Broadening

0 2 4 6 8 100

0.05

0.1

0.15

0.2

0.25

0.3

|m|

self

broa

dene

d ha

lfwid

th (c

m-1

/atm

)

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MK10 HCl Overtone Lineshapes 16

Isotopologues Comparison – Self Shift

-7 -5 -3 -1 1 3 5 7 9 11-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

mse

lf sh

ift (c

m-1

/atm

)

0 2 4 6 8 10-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

|m|

self

shift

(cm

-1/a

tm)

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The self-shift is not reported in HITRAN, nor any literature, yet it iscritical to precisely calibrate the wavenumber of a spectrometer

using typical HCl absorption pressure-pathlengths.

MK10 HCl Overtone Lineshapes 17

Isotopologues Comparison – Dicke

0 2 4 6 8 100

0.01

0.02

0.03

0.04

0.05

0.06

|m|

Dick

e pa

ram

eter

-7 -5 -3 -1 1 3 5 7 9 110

0.01

0.02

0.03

0.04

0.05

0.06

m

Dick

e pa

ram

eter

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The narrowing phenomenon is correlated with instrument variables such asresolution and aperture. The multispectrum fitting method allows a consistent

retrieval over many pressures with these instrument variables fixed. The isotopologue comparison highlights the reproducible trend that has been separated

from instrument variables.

MK10 HCl Overtone Lineshapes 18

Hamiltonian Parameters from constrained fit

G(H35Cl) 5667.9824970 0.31266838505E-05 G(H37Cl) 5663.9268346 0.57468641899E-05 B"(H35Cl) 10.440189334 0.47834078032E-06 B"(H37Cl) 10.424502872 0.10281972891E-05 D"(H35Cl) 0.52805708530D-03 0.12479988598E-07 D"(H37Cl) 0.52645439847D-03 0.39573635036E-07 H"(H35Cl) 0.16600000000D-07 Fixed H"(H37Cl) 0.22900000000D-07 Fixed B'(H35Cl) 9.8345885033D+01 0.43757773938E-06 B'(H37Cl) 9.8202784918D+01 0.10900827192E-05 D'(H35Cl) 0.51541494165D-03 0.87793443626E-08 D'(H37Cl) 0.51416332228D-03 0.29243450328E-07 H'(H35Cl) 0.15400000000D-07 Fixed H'(H37Cl) 0.21300000000D-07 Fixed

SQ/nu(H35Cl) 0.10469429511D-23 0.11154688922E-27 SQ/nu(H37Cl) 0.33157419710D-24 0.57034946781E-28 c1 (H35Cl) -.22686827401D-02 0.10987143469E-04 c1 (H37Cl) -.22476757421D-02 0.21406525775E-04

Guelachvili Opt. Comm. 19(1) 150-154, 1976

C01 = -2.60(27)x10-3, c0

2 = -0.86(57)x10-3

Tipping & Ogilvie JMS. 96 442-450, 1982Toth et al. JMS. 35, 110-126, 1970

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MK10 HCl Overtone Lineshapes 19

Summary and Future Directions• HCl spectra at multiple pressures have been

analyzed simultaneously for lineshape parameters

• Low pressure scan has intensity issues, but should improve accuracy of positions

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MK10 HCl Overtone Lineshapes 20

Acknowledgements

• NASA ACLR• OCO-2 ABSCO• Linda Brown• Keeyoon Sung• Malathy Devi• D. Chris Benner

6/16/2014

© 2014 California Institute of Technology. Government sponsorship acknowledged.

MK10 HCl Overtone Lineshapes 21

Pressure Broadening – HITRAN

m Self WidthSelf Width

ErrorHITRAN Self

Width

Percent Difference

from HITRAN

-5 0.2088 0.0001 0.213 1.9336

-4 0.2346 0.0001 0.238 1.4042

-3 0.2439 0.0001 0.242 0.7758

-2 0.2366 0.0001 0.229 3.2751

-1 0.22 0.0001 0.213 3.2442

1 0.2131 0.0001 0.201 5.9173

2 0.2246 0.0001 0.215 4.3936

3 0.2299 0.0001 0.224 2.6022

4 0.2223 0.0001 0.218 1.9253

5 0.2016 0.0001 0.197 2.2703

6 0.1752 0.0001 0.169 3.6236

7 0.1484 0.0001 0.139 6.6191

8 0.1269 0.0001 0.111 14.05379 0.108 0.0002 0.096 12.2358

H35Cl

m Self WidthSelf Width

ErrorHITRAN Self

Width

Percent Difference

from HITRAN

-4 0.2323 0.0002 0.238 2.3542

-3 0.2420 0.0002 0.242 0.0041

-2 0.2350 0.0002 0.229 2.5926

-1 0.2178 0.0003 0.213 2.2151

1 0.2109 0.0003 0.201 4.8610

2 0.2229 0.0002 0.215 3.6072

3 0.2277 0.0002 0.224 1.6368

4 0.2200 0.0002 0.218 0.8793

5 0.1994 0.0002 0.197 1.1825

6 0.1733 0.0002 0.169 2.5010

7 0.1469 0.0003 0.139 5.5937

8 0.1254 0.0004 0.111 12.7785

9 0.1082 0.0006 0.096 12.4713

H37Cl

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MK10 HCl Overtone Lineshapes 22

Linestrength – HITRANm Intensity

HITRAN intensity Difference

percent difference

-5 6.66E-21 6.38E-21 2.83E-22 4.44

-4 8.83E-21 8.44E-21 3.93E-22 4.66

-3 9.90E-21 9.46E-21 4.47E-22 4.73

-2 8.93E-21 8.53E-21 4.05E-22 4.74

-1 5.46E-21 5.21E-21 2.45E-22 4.71

1 6.02E-21 5.75E-21 2.71E-22 4.71

2 1.09E-20 1.04E-20 4.84E-22 4.66

3 1.33E-20 1.27E-20 5.95E-22 4.69

4 1.31E-20 1.25E-20 5.78E-22 4.62

5 1.09E-20 1.04E-20 4.80E-22 4.61

6 7.90E-21 7.54E-21 3.54E-22 4.70

7 5.02E-21 4.80E-21 2.20E-22 4.59

8 2.83E-21 2.71E-21 1.20E-22 4.42

9 1.42E-21 1.37E-21 5.99E-23 4.39

m IntensityHITRAN intensity Difference

percent difference

-4 2.79E-21 2.69E-21 1.02E-22 3.79

-3 3.13E-21 3.02E-21 1.19E-22 3.93

-2 2.83E-21 2.72E-21 1.11E-22 4.08

-1 1.72E-21 1.66E-21 6.32E-23 3.81

1 1.90E-21 1.83E-21 7.17E-23 3.92

2 3.44E-21 3.31E-21 1.36E-22 4.12

3 4.21E-21 4.05E-21 1.60E-22 3.94

4 4.14E-21 3.98E-21 1.56E-22 3.90

5 3.46E-21 3.32E-21 1.31E-22 3.95

6 2.50E-21 2.41E-21 8.77E-23 3.64

7 1.59E-21 1.54E-21 5.39E-23 3.51

8 8.96E-22 8.68E-22 2.83E-23 3.26

9 4.55E-22 4.37E-22 1.81E-23 4.15

H35Cl H37Cl

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MK10 HCl Overtone Lineshapes 23

Isotopologues Comparison – Line strengthsPoint Ratio

2 3.16

3 3.16

4 3.16

5 3.17

6 3.16

7 3.17

8 3.16

9 3.16

10 3.15

11 3.17

12 3.16

13 3.16

14 3.12

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