DETERMINATION OF PRESSURE BROADENING AND SHIFTS FOR THE FIRST OVERTONE 2←0 OF HCL Brennan M....
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Transcript of DETERMINATION OF PRESSURE BROADENING AND SHIFTS FOR THE FIRST OVERTONE 2←0 OF HCL Brennan M....
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
6/16/2014
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/
6/16/2014
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
6/16/2014
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
6/16/2014
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
)
6/16/2014
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
6/16/2014
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
6/16/2014
MK10 HCl Overtone Lineshapes 12
Spectral Fitting no constraints• Full Physics fits with LabFit to get pressure broadening and pressure shift
6/16/2014
MK10 HCl Overtone Lineshapes 13
Fitting Spectra with constraintsIntensities with Honl-London Factors, exp(hv/kT), positions with B0,B2, D0,D2, H0, H2
6/16/2014
MK10 HCl Overtone Lineshapes 14
Linestrength – HITRAN• On average 2.6%
higher than HITRAN
• Both intensity and pressure broadening are consistently higher than HITRAN
6/16/2014
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
)
6/16/2014
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)
6/16/2014
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
6/16/2014
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
6/16/2014
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
6/16/2014
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
6/16/2014
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
6/16/2014
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
6/16/2014