AGW Observer

Observations of anthropogenic global warming

Papers on laboratory measurements of CO2 absorption properties

Posted by Ari Jokimäki on September 25, 2009

This is a list of papers on laboratory measurements of the absorption properties of carbon dioxide. In the context of these paperlists this is a difficult subject because only few of the papers are freely available online, so we have to settle on abstracts only (of course, interested reader can purchase the full texts for the papers from the linked abstract pages). However, I don’t think that matters that much because the main point of this list really is to show that the basic research on the subject exists. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (September 23, 2012): Burch & Gryvnak (1966) added.
UPDATE (February 6, 2011): Miller & Watts (1984) added.
UPDATE (July 25, 2010): I modified the introduction paragraph a little to reflect the current content of the list. The old text was a little outdated.
UPDATE (June 22, 2010): Lecher & Pernter (1881) added.
UPDATE (March 31, 2010): Tubbs & Williams (1972), Rubens & Aschkinass (1898) and Ångström (1900) added.
UPDATE (March 6, 2010): Barker (1922) added.
UPDATE (November 19, 2009): Predoi-Cross et al. (2007) added.
UPDATE (September 25, 2009): Miller & Brown (2004) added, thanks to John Cook for bringing it to my attention (see the discussion section below).

Spectroscopic database of CO2 line parameters: 4300–7000 cm−1 – Toth et al. (2008) “A new spectroscopic database for carbon dioxide in the near infrared is presented to support remote sensing of the terrestrial planets (Mars, Venus and the Earth). The compilation contains over 28,500 transitions of 210 bands from 4300 to 7000 cm−1…”

Line shape parameters measurement and computations for self-broadened carbon dioxide transitions in the 30012 ← 00001 and 30013 ← 00001 bands, line mixing, and speed dependence – Predoi-Cross et al. (2007) “Transitions of pure carbon dioxide have been measured using a Fourier transform spectrometer in the 30012 ← 00001 and 30013 ← 00001 vibrational bands. The room temperature spectra, recorded at a resolution of 0.008 cm−1, were analyzed using the Voigt model and a Speed Dependent Voigt line shape model that includes a pressure dependent narrowing parameter. Intensities, self-induced pressure broadening, shifts, and weak line mixing coefficients are determined. The results obtained are consistent with other studies in addition to the theoretically calculated values.” [Full text]

Spectroscopic challenges for high accuracy retrievals of atmospheric CO2 and the Orbiting Carbon Observatory (OCO) experiment – Miller et al. (2005) “The space-based Orbiting Carbon Observatory (OCO) mission will achieve global measurements needed to distinguish spatial and temporal gradients in the CO2 column. Scheduled by NASA to launch in 2008, the instrument will obtain averaged dry air mole fraction (XCO2) with a precision of 1 part per million (0.3%) in order to quantify the variation of CO2 sources and sinks and to improve future climate forecasts. Retrievals of XCO2 from ground-based measurements require even higher precisions to validate the satellite data and link them accurately and without bias to the World Meteorological Organization (WMO) standard for atmospheric CO2 observations. These retrievals will require CO2 spectroscopic parameters with unprecedented accuracy. Here we present the experimental and data analysis methods implemented in laboratory studies in order to achieve this challenging goal.”

Near infrared spectroscopy of carbon dioxide I. 16O12C16O line positions – Miller & Brown (2004) “High-resolution near-infrared (4000–9000 cm-1) spectra of carbon dioxide have been recorded using the McMath–Pierce Fourier transform spectrometer at the Kitt Peak National Solar Observatory. Some 2500 observed positions have been used to determine spectroscopic constants for 53 different vibrational states of the 16O12C16O isotopologue, including eight vibrational states for which laboratory spectra have not previously been reported. … This work reduces CO2 near-infrared line position uncertainties by a factor of 10 or more compared to the 2000 HITRAN line list, which has not been modified since the comprehensive work of Rothman et al. [J. Quant. Spectrosc. Rad. Transfer 48 (1992) 537].” [Full text]

Spectra calculations in central and wing regions of CO2 IR bands between 10 and 20 μm. I: model and laboratory measurements – Niro et al. (2004) “Temperature (200–300 K) and pressure (70–200 atm) dependent laboratory measurements of infrared transmission by CO2–N2 mixtures have been made. From these experiments the absorption coefficient is reconstructed, over a range of several orders of magnitude, between 600 and 1000 cm−1.”

Collisional effects on spectral line-shapes – Boulet (2004) “The growing concern of mankind for the understanding and preserving of its environment has stimulated great interest for the study of planetary atmospheres and, first of all, for that of the Earth. Onboard spectrometers now provide more and more precise information on the transmission and emission of radiation by these atmospheres. Its treatment by ‘retrieval’ technics, in order to extract vertical profiles (pressure, temperature, volume mixing ratios) requires precise modeling of infrared absorption spectra. Within this framework, accounting for the influence of pressure on the absorption shape is crucial. These effects of inter-molecular collisions between the optically active species and the ‘perturbers’ are complex and of various types depending mostly on the density of perturbers. The present paper attempts to review and illustrate, through a few examples, the state of the art in this field.”

On far-wing Raman profiles by CO2 – Benech et al. (2002) “Despite the excellent agreement observed in N2 here, a substantial inconsistency between theory and experiment was found in the wing of the spectrum. Although the influence of other missing processes or neighboring bands cannot be totally excluded, our findings rather suggest that highly anisotropic perturbers, such as CO2, are improperly described when they are handled as point-like molecules, a cornerstone hypothesis in the approach employed.”

Collision-induced scattering in CO2 gas – Teboul et al. (1995) “Carbon-dioxide gas rototranslational scattering has been measured at 294.5 K in the frequency range 10–1000 cm−1 at 23 amagat. The depolarization ratio of scattered intensities in the frequency range 10–1000 cm−1 is recorded. The theoretical and experimental spectra in the frequency range 10–470 cm−1 are compared.”

The HITRAN database: 1986 edition – Rothman et al. (1987) “A description and summary of the latest edition of the AFGL HITRAN molecular absorption parameters database are presented. This new database combines the information for the seven principal atmospheric absorbers and twenty-one additional molecular species previously contained on the AFGL atmospheric absorption line parameter compilation and on the trace gas compilation.”

Rotational structure in the infrared spectra of carbon dioxide and nitrous oxide dimers – Miller & Watts (1984) “High-resolution infrared predissociation spectra have been measured for dilute mixtures of CO2 and N2O in helium. Rotational fine structure is clearly resolved for both (CO2)2 and (N2O)2, the linewidths being instrument-limited. This establishes that predissociation lifetimes are longer than approximately 50 ns.”

Broadening of Infrared Absorption Lines at Reduced Temperatures: Carbon Dioxide – Tubbs & Williams (1972) “An evacuated high-resolution Czerny-Turner spectrograph, which is described in this paper, has been used to determine the strengths S and self-broadening parameters γ0 for lines in the R branch of the ν3 fundamental of 12C16O2 at 298 and at 207 K. The values of γ0 at 207 K are greater than those to be expected on the basis of a fixed collision cross section σ.”

Investigation of the Absorption of Infrared Radiation by Atmospheric Gases – Burch et al. (1970) “From spectral transmittance curves of very large samples of CO2 we have determined coefficients for intrinsic absorption and pressure-induced absorption from approximately 1130/cm to 1835/cm.”

Absorption of Infrared Radiant Energy by CO2 and H2O. IV. Shapes of Collision-Broadened CO2 Lines – Burch et al. (1969) “The shapes of the extreme wings of self-broadened CO2 lines have been investigated in three spectral regions near 7000, 3800, and 2400 cm−1. … New information has been obtained about the shapes of self-broadened CO2 lines as well as CO2 lines broadened by N2, O2, Ar, He, and H2.”

High-Temperature Spectral Emissivities and Total Intensities of the 15-µ Band System of CO2 – Ludwig et al. (1966) “Spectral-emissivity measurements of the 15-µ band of CO2 were made in the temperature range from 1000° to 2300°K.”

Laboratory investigation of the absorption and emission of infrared radiation – Burch & Gryvnak (1966) “Extensive measurements of the absorption by H2O and CO2 have been made in the region from 0·6 to 5·5 microm. Two different multiple-pass absorption cells provided path lengths from 2 to 933 m, and sample pressures were varied from a few μHg to 15 atm. Approximately thirty new CO2 bands were observed and identified, and the strengths of the important bands determined. The H2O data provide enough information for the determination of the strengths and widths of several hundred of the more important lines. The wings of CO2absorption lines were found to be sub-Lorentzian, with the shapes depending on temperature, broadening gas, and wavelength in ways which cannot be explained by present theories. The absorption by H2O and CO2 samples at temperatures up to 1800°K has been studied from 1 to 5 microm. The transmission of radiation from hot CO2 through cold CO2 and from hot H2O through cold H2O has been investigated to determine the effect of the coincidence of emission lines with absorption lines.” Darrell E. Burch, David A. Gryvnak, Journal of Quantitative Spectroscopy and Radiative Transfer, Volume 6, Issue 3, May–June 1966, Pages 229–240, http://dx.doi.org/10.1016/0022-4073(66)90072-0.

Line shape in the wing beyond the band head of the 4·3 μ band of CO2 – Winters et al. (1964) “Quantitative absorpance measurements have been made in pure CO2 and mixtures of CO2 with N2 and O2 in a 10 m White Perkin-Elmer cell. With absorbing paths up to 50 m-atm, results have been obtained from the band head at 2397 cm−1 to 2575 cm−1.”

Emissivity of Carbon Dioxide at 4.3 µ – Davies (1964) “The emissivity of carbon dioxide has been measured for temperatures from 1500° to 3000°K over the wavelength range from 4.40 to 5.30 µ.”

Absorption Line Broadening in the Infrared – Burch et al. (1962) “The effects of various gases on the absorption bands of nitrous oxide, carbon monoxide, methane, carbon dioxide, and water vapor have been investigated.”

Total Absorptance of Carbon Dioxide in the Infrared – Burch et al. (1962) “Total absorptance… has been determined as a function of absorber concentration w and equivalent pressure Pe for the major infrared absorption bands of carbon dioxide with centers at 3716, 3609, 2350, 1064, and 961 cm−1.”

Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths – Herzberg & Herzberg (1953) “The spectrum of CO2 in the photographic infrared has been studied with absorbing paths up to 5500 m. Thirteen absorption bands were found of which eleven have been analyzed in detail.”

The Infrared Absorption Spectrum of Carbon Dioxide – Martin & Barker (1932) “The complete infrared spectrum of CO2 may consistently be explained in terms of a linear symmetrical model, making use of the selection rules developed by Dennison and the resonance interaction introduced by Fermi. The inactive fundamental ν1 appears only in combination bands, but ν2 at 15μ and ν3 at 4.3μ absorb intensely.”

Carbon Dioxide Absorption in the Near Infra-Red – Barker (1922) “Infra-red absorption bands of CO2 at 2.7 and 4.3 μ. – New absorption curves have been obtained, using a special prism-grating double spectrometer of higher resolution (Figs. 1-3). The 2.7 μ region, heretofore considered to be a doublet, proves to be a pair of doublets, with centers at approximately 2.694 μ and 2.767 μ. The 4.3 μ band appears as a single doublet with center at 4.253 μ. The frequency difference between maxima is nearly the same for each of the three doublets, and equal to 4.5 x 1011. Complete resolution of the band series was not effected, even though the slit included only 12 A for the 2.7 μ region, but there is evidently a complicated structure, with a “head” in each case on the side of shorter wave-lengths. The existence of this head for the 4.3 μ band is also indicated by a comparison with the emission spectrum from a bunsen flame, and the difference in wave-length of the maxima of emission and absorption is explained as a temperature effect similar to that observed with other doublets.” [For free full text, click PDF or GIF links in the linked abstract page]

Ueber die Bedeutung des Wasserdampfes und der Kohlensäure bei der Absorption der Erdatmosphäre – Ångström (1900)

Observations on the Absorption and Emission of Aqueous Vapor and Carbon Dioxide in the Infra-Red Spectrum – Rubens & Aschkinass (1898) “Our experiments carried out as described above on the absorption spectrum carbon dioxide very soon showed that we were dealing with a single absorption band whose maximum lies near λ = 14.7 μ. … The whole region of absorption is limited to the interval from 12.5 μ to 16 μ, with the maximum at 14.7 μ.” [For free full text, click PDF or GIF links in the linked abstract page]

On the absorption of dark heat-rays by gases and vapours – Lecher & Pernter (1881) Svante Arrhenius wrote in his famous 1897 paper: “Tyndall held the opinion that the water-vapour has the greatest influence, whilst other authors, for instance Lecher and Pernter, are inclined to think that the carbonic acid plays the more important part.”.

The Bakerian Lecture – On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction – Tyndall (1861) 150 years ago John Tyndall already showed that carbon dioxide absorbs infrared radiation. [Full text] [Wikipedia: John Tyndall]

Closely related

The HITRAN Database – The laboratory work results on the absorption properties of carbon dioxide (and many other molecules) is contained in this database.

25 Responses to “Papers on laboratory measurements of CO2 absorption properties”

  1. John Cook said

    Here’s another one (luckily a PDF is available online also): Near infrared spectroscopy of carbon dioxide I. 16O12C16O line positions – Miller (2004) “High-resolution near-infrared (4000–9000 cm-1) spectra of carbon dioxide have been recorded using the McMath–Pierce Fourier transform spectrometer at the Kitt Peak National Solar Observatory. Some 2500 observed positions have been used to determine spectroscopic constants for 53 different vibrational states of the 16O12C16O
    isotopologue, including eight vibrational states for which
    laboratory spectra have not previously been reported. Calibration by simultaneous use of CO near 4200 cm-1 and C2H2 near 6500 cm-1 provides absolute line position accuracies of 6.0×10-5 cm-1 (RMS) for strong, isolated transitions throughout the observed range. Fits with RMS errors <3.8×10-5 cm-1 have been obtained for the 20013 00001, 20012 00001, and 20011 00001 bands, RMS errors <6×10-5 cm-1 have been obtained for the 30014 00001, 30013 00001, 30012 00001, and 00031 00001 bands, and RMS errors <5×10-4 cm-1 for even the weakest fitted bands. This work reduces CO2 near-infrared line position uncertainties by a factor of 10 or more compared to the 2000 HITRAN line list, which has not been modified since the comprehensive work of Rothman et al. [J. Quant. Spectrosc. Rad. Transfer 48 (1992) 537]. The new line list satisfies the line position accuracies required for the next generation of CO2 remote sensing instruments, improves the capability of solar-viewing spectrometers to retrieve precise column CO2 measurements, and provides a secondary frequency standard in the near-infrared.”

  2. Ari Jokimäki said

    Well, I hoped that someone would come along and point out a paper that also has PDF freely online, and you delivered immediately, thanks!

  3. Ari Jokimäki said

    I added Predoi-Cross et al. (2007), see above.

  4. [...] Originally Posted by radioprius1 I'm asking for someone to explain how CO2 traps heat resulting in global warming. Ok, I wasn't sure if you meant the basic mechanism behind it or it. Carbon dioxide (CO2) consits of a single carbon atom and two hyrdogen atoms bonded to it, one on each side. Because greenhouse gasses are comprised of 3 or more atoms, they are loosely bonded and have a certain freedom of movement and thus are affected by longwave radiation in the form of vibrations. The carbon dioxide molecule can absorb infrared radiation and the molecule will vibrate. As molecules return to a ground state the molecule will release radiation which will likely be picked up by another molecule. This keeps the outgoing longwave radiation (OLR) close to the earth instead of being radiated out into space. The more greenhouse gas molecules you have the more this effect is intensified. Water vapor is the biggest contributor to the greenhouse affect and generally speaking, higher temperatures cause more evaporation which puts more water vapor into the atmosphere. Since the role of water vapor and it's myriad forms is still a bit confusing that is all I will say about that but there are plenty of papers on the subject. The rest starts getting confusing when you start arguing limits to infared radiation absorbtion and water vapor effects, Linzden's "iris hypothesis", feedbacks, and forcings but this give you the general idea. My best advice is to stay away from the alarmist and skeptic sites. They will only serve to confuse and polarize you. Links to papers on the study of CO2 and its interactions with longwave radiation [...]

  5. Anonymous said

    [...] fraction", has hovered around 43% since 1958. CO2 traps heat According to radiative physics and decades of laboratory measurements, increased CO2 in the atmosphere is expected to absorb more infrared radiation as it escapes back [...]

  6. Ari Jokimäki said

    I added full text link to Tyndall (1861).

  7. [...] Originally Posted by gordonleslie the real reason for growing scepticism? as time progresses the alarmist theories unravel as we can empirically measure prediction (theory) versus actual. Empirical measurements all appear to be backing up the science: CO2 has been confirmed as a greenhouse gase (Herzberg 1953, Burch 1962, Burch 1970, etc). [...]

  8. [...] first proposed by the French scientist Joseph Fourier in 1824. Greenhouses gases, such as carbon, help trap heat in our atmosphere. No one disputes that our planet is subject to a natural greenhouse effect – not even so [...]

  9. Ari Jokimäki said

    I added Barker (1922).

  10. Ari Jokimäki said

    I added Tubbs & Williams (1972), Rubens & Aschkinass (1898) and Ångström (1900).

  11. Ari Jokimäki said

    I added Lecher & Pernter (1881).

  12. [...] [...]

  13. Ari Jokimäki said

    I modified the introduction paragraph a little to reflect the current content of the list. The old text was a little outdated.

  14. Ari Jokimäki said

    I added Miller & Watts (1984).

  15. [...] to read up on the scientific basis for classifying carbon dioxide as a greenhouse gas, start with this list of 25 peer-reviewed scientific studies on the topic. For a description of the various human sources of carbon dioxide emissions within the [...]

  16. I have no problem accepting that CO2 absorbs IR frequencies better than O2 or N2. I question how much heat is absorbed by 390 ppm. Since I contend that the sensible heat released by our energy usage is the cause of global warming, I would like to see a model based on data which has no humanly induced heat effects. Data for the previous 400,000 years shows five temperature/CO2 cycles. Temperature and CO2 rose together but temperature fell much sooner and faster than CO2. This indicates that CO2 is not supporting Temperature in the absence of heat input.. It also suggests that temperature rise is the cause of rising CO2,(where solar heat is the only input. These data also a “climate sensitivity” 10 times greater than we currently experience. If these data are being used to project a CO2/ temperature correlation, they cannot be relied on to establish a cause/effect relationship under today’s situation where sensible heat alone can account for the rise in temperature. Some have tried to claim that sensible heat is immediately radiated to outer space and has no influence on global warming. If heat is really the problem, we should not even consider nuclear power. In support of Doug’s explanation of why removing CO2 by photosynthesis is effective, when CO2, H2O, and sunlight are converted to cellulose (trees) 4841 BTUs are absorbed by this endothermic reaction. CO2 is beneficial and until I hear a convincing explanation why sensible heat does not cause global warming, I will continue to say that blaming CO2 for global warming is rubbish.

  17. Ari Jokimäki said

    I have no problem accepting that CO2 absorbs IR frequencies better than O2 or N2. I question how much heat is absorbed by 390 ppm.

    You only need to look at scientific observations to get an answer to your question:

    http://agwobserver.wordpress.com/2010/02/08/observations-of-anthropogenic-global-warming/

    In summary, we measure directly from atmosphere just the amount of absorption that theories say carbon dioxide should absorb. We actually can measure carbon dioxide concentration of the atmosphere based on the carbon dioxide IR frequency absorption.

    Since I contend that the sensible heat released by our energy usage is the cause of global warming, I would like to see a model based on data which has no humanly induced heat effects.

    It is common practise to run climate models both with and without anthropogenic forcing. You can see some such studies here:

    http://agwobserver.wordpress.com/2009/10/23/papers-on-models-vs-observations/

    Data for the previous 400,000 years shows five temperature/CO2 cycles. Temperature and CO2 rose together but temperature fell much sooner and faster than CO2.

    It’s quite well known that timings of the past climate changes have been generally dictated by changes in Earth’s orbit parameters. It is also quite well known that the greenhouse gases are very important factor dictating the amplitude of the climate changes:

    http://agwobserver.wordpress.com/2009/08/15/papers-on-ghg-role-in-historical-climate-changes/

    Whenever something causes atmospheric greenhouse concentrations to rise, temperature also rises. We can’t explain the amplitude of those past changes without greenhouse gases (at least without huge climate sensitivity).

    CO2 is beneficial and until I hear a convincing explanation why sensible heat does not cause global warming, I will continue to say that blaming CO2 for global warming is rubbish.

    Whether the “sensible heat” causes global warming or not does not change anything in carbon dioxide’s greenhouse effect. You cannot handwave some climate forcing away by suggesting that there’s another climate forcing. And really, “rubbish”? Is Newton’s theory of gravity rubbish just because Einstein’s theory of gravity is more correct? Get real.

  18. [...] Exhibit B: CO2 is Known To Trap Infrared Radiation (Can call it “Heat”)  [...]

  19. barry said

    Ari, I wonder if you know of any studies concenred empirical laboratory tests of changes in heat of a volume of air when CO2 is added? To many skeptics, this test is the missing link – the “empirical” link, if you like. You can talk about radiative absorption to these people and they won’t accept it. Point out Tyndall and they’ll quote some half-baked critic and ask to see evidence of anyone else doing physical tests of the greenhouse effect in the lab.

    Any ideas?

  20. Ari Jokimäki said

    As one partial answer to your question, I added Burch & Gryvnak (1966) to above list. It doesn’t measure heat but it does seem to measure both absorption and emission of carbon dioxide (and water vapor).

    I remember vaguely seeing some webpage giving kind of demonstration you are asking.

    There are also the measurements of carbon dioxide radiating IR radiation back to surface of the Earth (you can find some papers from my DLR list). That is quite certain sign of carbon dioxide heating effect (how could Earth’s surface possibly receive this thermal radiation from atmospheric carbon dioxide and not experience heating effect?).

    And at any case, measurement of absorption means that part of the thermal radiation that Earth’s surface radiated went missing. Energy doesn’t disappear and energy does have a habbit to warm things up, and here some of energy Earth tried to send to space disappeared in the way. Some place got warmer or more energetic.

  21. barry said

    Thanks Ari, I looked through those paper lists here before I put my question. I begin to wonder if there are so few or no papers because this effect is as controversial as boiling a kettle, but it does seem odd that empirical testing of the effect of raised levels of CO2 on the temperature of a volume of air in the laboratory doesn’t appear to be a solid part of the literature – or at least, I don’t know why it should be so difficult to find. I checked all citations for Tyndall’s papers – nothing there. Tried various search terms in google scholar. Zip. I’ve seen the experiment done on youtube, but not anywhere can I find a peer-reviewed example. It would be great to have a fistful of these to show critics that this has ben done; a useful stepping stone between spectroscopic analysis in the lab and measurements of radiance changes from above the earth.

    We can tell them that it would violate the laws of physics for there NOT to be atmospheric warming from observed ‘darkening’ of radiance bands, but that is pie in the sky for a good number ‘skeptics’ compared to good old meat and potatoes lab tests of the enhanced greenhouse effect.

  22. barry said

    Just noticed we were born in the same year (June 4, me). Cheers, cousin.

  23. Ari Jokimäki said

    It seems that I’m few months older than you…

  24. Dan Alter said

    The only relevant measurement for CO2 greenhouse effect is the Beer-Lambert equation which describes how much doubling CO2 levels affects infrared absorption.
    CO2 absorbs 50% infrared at 30ppm, double the ppm to 60 and it absorbs half more or 75% of the infrared, double again to 120ppm and it absorbs half more of the infrared not yet absorbed or 87.5%.

    At 240ppm = 94.75% of infrared absorbed.

    Obviously at 400ppm we are 97%.

    Ergo above 400ppm any remaining infrared absorption by CO2 is negligible. However we do get that lovely plant fertilization effect.

    Notice changing the initial 30 ppm observation doesn’t change the argument. We could start at 200ppm and we would be at 75% absorption.

    I will also point out that planet temperatures have not risen for 17 years, taking all warmist models well below their predicted temperatures. This result would be expected by
    the fact that CO2 greenhouse effect has stopped. It has always been, even while rising to its maximum possible effect at 400ppm, a very small part of all greenhouse gasses effect on Earth.

    Show me that the Beer-Lambert equation does not hold for CO2 infrared absorption, or admit your arguments for CO2 caused global warming are rubbish.

  25. Ari Jokimäki said

    Your argument has been addressed here:

    http://agwobserver.wordpress.com/2010/03/18/when-carbon-dioxide-didnt-affect-climate/

    And here:

    http://www.skepticalscience.com/saturated-co2-effect.htm

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