Solstice blogging - a contrast in two styles - vivace versus con uno denialisto

I was reading Peter Gleick's anatomical dissection of the Uncle Lester Senator Rafael Edward "Ted" Cruz (Asshat-Texas) hearing (OnymousGuy wrote about it in Happer in the Hopper).

Peter was quite funny. Take the time to go read Everything Senator Ted Cruz said about climate change in this NPR interview was wrong, including the comments. You will feel refreshed.

Halfway through the comments, I saw this contribution from the Sage of Corbett. and then Peter Gleick's reply - that is the proper response. Note the contrasting styles. 

Gordon J. Fulks, PhD
Corbett, Oregon USA
December 10, 2015

Peter Gleick gives himself away by quoting the propaganda website “Skeptical Science.” Science is NOT a series of political talking points from Cook and Nuccitelli.

Science is likewise not a matter of what the scientific labor unions say. Does the US National Academy of Sciences have a policy that the Earth is round? Do they really get to dictate ANY science? Of course not! Science is the product of individual scientists, utilizing logic and evidence NOT consensus and authority. Glieck should understand that!

The first of the scientific societies, the Royal Society, has the motto “Take nobody’s word for it.” Today, they and Gleick would rather forget that, because they do not want to be questioned.

Yet we have to question Gleick’s use of evidence from propagandists and his inability to get to the real scientific issues. While the planet has warmed a little out of the depths of the Little Ice Age (from about 1830) and did warm a little since the end of WW2, none of this correlates with rising man-made CO2 except for the period from about 1977 to 1997. How can a little warming over two of the last seven decades when CO2 has been rising due to human activity be considered a definitive correlation? The real correlation is with ocean cycles.

And as Professor John Christy correctly pointed out at the Senate Hearing chaired by Senator Cruz on Tuesday, the Climate Models come nowhere close to matching the robust satellite and radiosonde data. Even Santer et al., PNAS 2012 admitted that there is an enormous difference between the Climate Models and reality. This is especially true in the tropical mid-troposphere where the predicted “Hot Spot” is missing.

In short, Senator Ted Cruz (a graduate of Princeton University) understands the science FAR BETTER than Peter Gleick.

Gordon J. Fulks, PhD (Physics)

And Gleick's response:

Peter Gleick
December 10, 2015

Thanks, Gordon. You always crack me up.
 

More from the mail bag - denialisti and incognoscenti

Jim Diamond gets mail. He shares. I am pretty sure that it had something to do with this: Guest commentary "Climate change is the world's most pressing issue".

  

Climate Change
From: Greg
Sent:     Saturday, November 21, 2015 5:55 PM
To:     Jim Diamond
      
There is no doubt that mans presence on Earth has affected the environment but it is also an environment that has been changing since creation.  Liberal climate criers refuse to debate facts when trends show temperature increases that have slowed or stopped, the fact Antarctica has added more ice than the Artic has lost, or better the fact climate activists do everything they can to silence scientists that offer opposing research.  Worse, are idiot liberals like yourself and Obama who say climate change is more dangerous than terrorist as the bodies pile up.  How sad but fitting that over one hundred people were killed by terrorists in Paris at the same time Al Gore, who flies around in a climate changing Jet, was there telling your story.  I hope you are never caught in a terrorist attack but if you are I suspect you will quickly decide that the terrorist event is far more life threatening than anything you have ever preached about climate.

GBrown

 There is nothing one can say in response that will change this person's mind, IMO.

RE: Did you get my latest Op-Ed?
Gordon Fulks
Sent:     Sunday, December 06, 2015 5:49 PM
To:    
JoLinn Kapstra ‎
Cc:     Jim Diamond; Thomas Hellie; global-warming-realists
     
Thanks JoLinn,

I appreciate the prominent placement on your first page no less!  Since the pdf file is too large to send to our Global Warming Realists Google Group, I will show where it can be found online:

http://nw-connection.com/blog1/wp-content/uploads/2015/12/NWConn_Dec_2015_.pdf

I will also copy Linfield Chemistry Professor Jim Diamond and Linfield President Thomas Hellie, because of the continuing challenge that I am presenting to them.  If they really believe the climate hysteria they are selling to unsuspecting students, they need to defend it.  They will not be able to duck accountability forever.  At least Professor Diamond should be able to understand the need to defend theses.  He certainly had to do so at least once in his life when he got his PhD.  A professorship is not a blanket license to pedal climate nonsense.

Merry Christmas, Ho, Ho, Ho!

Gordon

Gordon J. Fulks, PhD (Physics)
Corbett, Oregon USA

Date: Mon, 7 Dec 2015 00:25:15 +0000
From: jolinn
To: gordonfulks
Subject: Re: Did you get my latest Op-Ed?

Hi Gordon,

You made the cover! Attached is a pdf of the December issue.
Merry Christmas!
JoLinn

JoLinn Kampstra, Publisher
The Northwest Connection

From: Gordon Fulks
To: JoLinn Kapstra
Sent: Sunday, December 6, 2015 2:56 PM
Subject: Did you get my latest Op-Ed?

Hi JoLinn,

Since I have not heard from you in response to the Op-Ed I submitted about November 24, could you tell me if it was received and what you thought of it?

I've been too busy to follow up until now.

Hope you had a Happy Thanksgiving.  We drove to Walla Walla to celebrate with my 92+ year old aunt and managed to get there and back before a winter storm made the Gorge dangerous.

Gordon

There is nothing one can say in response that will change this person's mind, IMO.

Diamonds - and CO2 - are forever II (wonkish and long)

I have been thinking a lot about David Archer's models for the long-timescale chemical reactions of CO₂ and the its radiative forcing integrated over its entire lifetime. In particular, I was interested in the dynamics described in this figure reproduced from his book, The Long Thaw.

 The caption says a great deal: "Model simulation of atmospheric CO₂ concentration for 40,000 years following after a large CO₂ release from combustion of fossil fuels. Different fractions of the released gas recover on different timescales."

In the original Archer model[1-4], an instantaneous pulse of CO₂ is injected into the atmosphere at time t₀ and is chemically removed through interactions with the oceans, silicate rocks, and igneous rocks; each of these reactions is modeled with first-order kinetics but with different lifetimes.

This model can be used to address two questions:
(1) What is the ratio of the total accumulated energy due to global warming to the energy of combustion?

ΔF = α ln(C/C_o) [see, for example, NOAA AGGI]

[The time required for this energy to equal the heat of coumbustion combustion [OG: Maybe someday I will start believing that spell checker] for a given fossil fuel was discussed in Onymous Guy's earlier post, Diamonds - and CO2 - are forever]
  
(2) What is the effect of the logarithmic nature of the forcing function on the amount of total accumulated energy due to global warming added to the earth's energy budget, in particular, does it level off?

Here is the mathematical development:
(Apologies ahead of time, but these are not text, but images from a Mathematica notebook obtained via Grab. I am open to suggestions on improvements in capturing these sorts of images.)

Let's take a look at this pulse function when atmospheric CO₂ is instantly doubled:

The different decay processes are a little more visible in a plot logarithmic in time.

This plot covers a million years; clearly, if this model is at all accurate, one must conclude that although most CO₂ is removed from the atmosphere within a few hundred years, a significant fraction persists in the atmosphere for times that are long on the geological time scale.

Additional Questions
What about the lifetime integrated radiative forcings as the magnitude of the initial CO₂ pulse is increased? What effect will dominate, the very long lifetime of 25% of atmospheric CO₂, or the plateau due to the logarithmic increase in forcing?

Let's compare the exact (equation (9) ) and approximate (linearized, as in equation (12) ) lifetime integrated radiative forcings:

As you can see, there is little difference between the exact and linearized forcings, suggesting that the effect of the logartihmic function is negated by the fraction of atmospheric CO₂ which persists on the geological time scale.

The ratio of the approximate forcing to the exact term is shown in the next graph.

We observe that radiative forcing is very nearly linear in terms of the magnitude of the initial pulse of CO₂; furthermore, the logarithmic term reduces radiative forcing by less than 6% relative to the linear term even up to a pulse above ambient pressure up to 800 ppmv CO₂, a net amount nearly three times the amount in the atmosphere today.

The orange curve in the above figure has a slight curvature, so we investigated the effect of linear, quadratic, and cubic fits to a sequence of data separated by 10 ppmv.

Here is a graphical comparison of all three models with the exact result.

It is difficult to distinguish the exact result from the quadratic model except for points well away from the center of the fitting region.

A Final Remark
The integrated "pulse function" g(t) (equation (11) above) provides an effective lifetime for atmospheric CO₂ of 17303.3 yrs - as far as radiative forcing is concerned. This allows one to explicitly compare the total energy added to the atmosphere from the enthalpy of combustion of a fossil fuel with the accumulated energy due to global warming arising from the CO₂ added to the atmosphere through combustion. The following table summarizes, by fuel type, the ratio of lifetime-accumulated radiative forcing to the enthalpy of combustion; this ratio is dimensionless.

Conclusions
(1) As one can see from the above table, the effects of global warming are ten thousand times larger than that of combustion, and twice that for coal and coal products such as coke.
(2) The effects of global warming over the lifetime of CO₂ are very nearly linear in the amount of CO₂ added to the atmosphere.

The effects of carbon combustion are nearly eternal, as David Archer put it. And the addition of carbon dioxide to the atmosphere is an unforgiving and relentless burden, with no cushion at all. The more carbon that is burnt, the worse off we will be.

I would call this a very strong argument for decarbonization of the economy.

On Models
The Archer model is just that and the conclusions discussed above should not be oversold; I think this quote from his 2005 work is quite relevant:

However, the 300 year simplification misses the

immense longevity of the tail on the CO₂ lifetime, and

hence its interaction with major ice sheets, ocean methane

clathrate deposits, and future glacial/interglacial cycles. One

could sensibly argue that public discussion should focus on

a time frame within which we live our lives, rather than

concern ourselves with climate impacts tens of thousands of

years in the future. On the other hand, the 10 kyr lifetime of

nuclear waste seems quite relevant to public perception

of nuclear energy decisions today. A better approximation

of the lifetime of fossil fuel CO₂ for public discussion might

be ‘‘300 years, plus 25% that lasts forever.’’

References
[1] Multiple timescales for neutralization of fossil fuel CO₂
Archer, David;  Kheshgi, Haroon;  Maier-Reimer, Ernst (1997),
Geophysical Research Letters,vol. 24 (4) p. 405-408, doi:10.1029/97GL00168.

[2] Archer, D. (2005), Fate of fossil fuel CO₂  in geologic time, J. Geophys. Res., 110, C09S05, doi:10.1029/2004JC002625.

[3] Archer, D. The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate (Princeton Univ. Press, 2008).

[4] Inman, M. (2008), Carbon is Forever, Nature Climate Change, 2008(12), doi:10.1038/climate.2008.122.

Supplement

Onymous Guy supposedly features "The odd ejecta from around the world". In that spirit, here is the lurid cover to "Diamonds are Forever", a slogan that Onymous Guy hopes surely galls The Sage of Corbett. And here are two other lurid covers, because Kurt Vonnegut, Jr. - who almost certainly would have had no patience with the denialisti - used this device in his novels. The Sirens of Titan remains one of my favorite novels. This novel also introduced me to that Vonnegut character, Winston Niles Rumfoord. Venus On The Half Shell acquired a life of its own outside of Vonnegut's novels, although it was supposedly one of Kilgore Trout's novels, and was actually written by Phillip Jose Farmer, another author I admired.

From Wikipedia

Trout, who has supposedly written over 117 novels and over 2000 short stories, is usually described as an unappreciated science fiction writer whose works are used only as filler material in pornographic magazines.

Hence the lurid covers.

One data point does not a trend make, but ...

Today's report from the Japan Metoreological Agency caught my eye.

The monthly anomaly of the global average surface temperature in November 2015 (i.e. the average of the near-surface air temperature over land and the SST) was +0.54°C above the 1981-2010 average (+0.88°C above the 20th century average), and was the warmest since 1891. On a longer time scale, global average surface temperatures have risen at a rate of about 0.71°C per century.

 Five Warmest Years (Anomalies)

1st. 2015 (+0.54°C), 2nd. 2013 (+0.31°C), 3rd. 2001 (+0.26°C), 4th. 2012 (+0.25°C), 5th. 2014, 2006, 2004, 1997 (+0.24°C)

This November anomaly is +0.23°C warmer than the second warmest November, two years ago.

Distribution of Anomalies

The cold spot in the  USA west of the Rockies will undoubtedly give birth to a chorus of "No warming" from the usual denialisti and incognoscenti.

Happer in the hopper

Dr. William Happer, Cyrus Fogg Bracket Professor of Physics, Princeton University, and buddy of Gordon Fulks, local incognoscento, ...

"I again ask whether or not Linfield College will permit any debate of this topic between knowledgeable proponents on both sides of the issue. After they invited Professor Michael Mann to make the case for climate alarmism (via his infamous ‘Hockey Stick’ graph) several years ago, they refused to consider any counter presentation, even from Princeton Professor of Physics, William Happer, a member of the US National Academy of Sciences." 

(OnymousGuy replies with a mordant snicker, and quite possible other sorts of snickers as well).
[Happer] ... has been in the news in the last day. He does not seem very happy about it.

My guess is that it had something to do with that headline in the Guardian.

Or it might have been the headline in the New York Times.

Or it might have been the headline in The Nation.

Or it just might have been the very fun event at the circus maximus known as the U.S. Senate Committee on Commerce, Science, & Transportation, Senator John Thune. (R-StateOfIgnorance) Chairman,

starring Uncle Lester Senator Rafael Edward "Ted" Cruz (R-WoefulStateOfIgnorance) and candidate for the Grand Old Party's nomination for President.

You can read for yourself the testimony of the Cyrus Fogg Bracket Professor of Physics, Princeton University. Better yet, read Eli's live-blogging of the event.

Please, no snickering.

Even ExxonMobil says climate change is real

From today's Washington Post.

Even ExxonMobil says climate change is real. So why won’t the GOP?
By Fred Hiatt Editorial page editor December 6 at 6:59 PM

To understand how dangerously extreme the Republican Party has become on climate change, compare its stance to that of ExxonMobil.

… With no government action, Exxon experts told us during a visit to The Post last week, average temperatures are likely to rise by a catastrophic (my word, not theirs) 5 degrees Celsius, with rises of 6, 7 or even more quite possible.

What then explains the know-nothingism of today’s Republicans? Some of them see scientists as part of a left-wing cabal; many of them doubt government’s ability to do anything, let alone something as big as redirecting the economy’s energy use. Almost all of them, along with quite a few Democrats, would rather not tell voters that energy prices need to rise for the sake of the environment.

 I think it is fair to repeat Fred Hiatt's question.

Even ExxonMobil says climate change is real. So why won’t the Oregonian?

Diamonds - and CO2 - are forever

Skeptical Science has addressed a related question,

Climate Myth...
It's waste heat
"Global warming is mostly due to heat production by human industry since the 1800s, from nuclear power and fossil fuels, better termed hydrocarbons, – coal, oil, natural gas. Greenhouse gases such as carbon dioxide (CO2 play a minor role even though they are widely claimed the cause." (Morton Skorodin)

Gordon Fulks has repeated assertions that CO2 doesn't matter. Here is his latest:

Unfortunately, proponents of Catastrophic Anthropogenic Global Warming continually sidestep all such tests, arguing as Diamond does, that CO2 is a greenhouse gas and adding more to the atmosphere has to warm the planet. That may be trivially true but numerically insignificant.

This last bit - "CO2 play a minor role even though they are widely claimed the cause" is a favorite "fulks-tale" that percolates through the nutosphere. Боже мой, it is good that real scientists call him out.

Being Onymous Guy, I felt I had to do my own calculation: I used data from controversial sources like NIST, NOAA, EIA, the usual rogue’s gallery.

The answer depends on the carbon source, but it boils down to this: within a year or so, regardless of source, the energy added to the planet through increased radiative forcings - the $25 term for the effects of global warming - exceed the enthalpy of combustion of that source.

The really bad news is that, once added the atmosphere, CO2 and its effects persist, not for millenia, but for hundreds of thousands of years, so the energy of combustion is extremely small compared to the lifetime accumulated radiative forcings from that added CO2.

As David Archer wrote,

The notion is pervasive in the popular and scientific literature that the lifetime of anthropogenic CO₂ released to the atmosphere is some fuzzy number measured most conveniently in decades or centuries. The reality is that the CO₂ from a gallon out of every tank of gas will continue to affect climate for tens and even hundreds of thousands of years into the future.

Source: Nature Climate Change

Those fun moments of hardware gltitches

Onymous Guy has been very edgy at the computer, because Mathematica seemed to be consuming enormous resources, overall response times were unusually slow, and the iBook Pro cursor had developed a mind of its own, exploring all quadrants of screen as if guided by Nemesis herself, exacting retribution for all of Onymous Guy's intemperate moments.

So after using The Google, as our unelected president C-Plus Augustus called it, we tried this.

Portable Macs with non-removable batteries:

• Make sure the Mac is plugged in to AC power.
• On the built-in keyboard, press and hold the Shift, Option, and Control keys on the left side and press the power button. 
• Release all the keys at once, and then turn the Mac on normally.

As always, we get very excited whenever we get to push four buttons at once, but Time Machine, which has disappointed us badly once, seems to be working.

Nemesis seems to have left us, at least for now.

Bullshit!

There is a new gauntlet thrown to the ground, an academic challenge to the greatly under-appreciated Sokal paper, Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity, that appears in the latest issue of the hitherto relatively still waters of the open-access journal, Judgment and Decision Making:

We can't tell if this is bullshit or not, but it declares itself (in fifteen journal pages), to be an academic study of bullshit.

The primary author, Gordon Pennycook, a Ph.D. candidate in Cognitive Psychology at the University of Waterloo, appears to have already published over two dozen articles.

We thank Bernard Cleyet for bringing this to the attention of the Phys-L community.

Our personal opinion is that the trail-blazing work of Sokal has set a standard that will be extremely difficult to match, let alone exceed, despite the many noble attempts reported in the invaluable Journal of Improbable Research.

I, for one, am always appreciate of these cross-disciplinary opportunities. With due consideration after  years of penal servitude on promotion and tenure committees, Onymous Guy thinks that, regardless of the academic merits of this publication, mastery of bullshit will advance one's career in academia a great deal.

That darn coal lobby!

I read with interest the letter from Robert M. Duncan (Affordable, Reliable Coal, Dec. 2, 2015).

Is this the same Robert M. “Mike” Duncan who chaired the Republican National Committee at the end of the 2nd George W. Bush administration? The same “Mike” Duncan who as late as 1996 was still defending the tobacco industry?

His position is odd, because on this same day, I read the abstract of a study released the same day by George D. Thurston et al., New York University School of Medicine, Departments of Environmental Medicine and Population Health,“Ischemic Heart Disease (IHD) Mortality and Long-Term Exposure to Source-Related Components of U.S. Fine Particle Air Pollution”.

Dr. Thurston and his colleagues studied risk factor data “for 445,860 adults in 100 U.S. metropolitan areas followed from 1982 to 2004 for vital status and cause of death”. They concluded “Long-term PM2.5 exposures from fossil fuel combustion, especially coal burning, but also from diesel traffic, were associated with increases in IHD mortality in this nationwide population.” As the Washington Post put it on the same day,”Coal is king among pollution that causes heart disease, study says”.

To Mr. “Mike” Duncan, who seems to have a connection with the aptly named American Crossroads, I say, “Thank you for smoking.”

The real FTIR spectrum of CO2 (wonkish)

I was reading through the comments on "Climate change is the world's most pressing problem"
and came across this bit of swill from one Chuck Wiese, Meteorologist - who also seems to have impressed the folks at Skeptical Science:

1/22/2015 7:16 PM

"Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth's atmosphere." Yes, water vapor is a greenhouse gas, but water vapor is limited to its equilibrium vapor pressure at a given temperature. Any more, and it condenses — a phenomenon we know well in the Northwest. Direct measurement of infrared absorption by CO2 — an experiment I have repeated many times with my chemistry students — is not affected by the presence of water vapor."

This statement by Jim Diamond is demonstrably false and as a chemistry professor, he ought to know better. Water vapor bands in the infrared are shared with CO2 in up to 37% of the absorption wavelengths from CO2, and CO2 IS NOT the "single most important climate- relevant greenhouse gas in the earth's atmosphere." The cross absorption and emission between these gases is very significant."

So I thought I would dig into the archives and see what I had on the infrared spectrum of CO₂. Here's a little bit of background on this type of experiment.

A Classic Physical Chemistry Experiment

The difference between adjacent vibrational states of a molecule usually lies in the infrared (IR) portion of the electromagnetic spectrum.
These energy differences can be related to physical properties of the molecule, such as the distance between atoms (bond length), the masses of the atoms, and properties related to the molecular potential energy surface.

These energy differences are measured by comparing the transmission of electromagnetic radiation through a region between a source and a detector, first, without a sample present, and second, with a sample present. The ratio of the latter to the former is called the the transmission coefficient, T. The differences are due to the presence of the sample.

Most modern IR instruments are Fourier-Transform (FT) rather than dispersive spectrometers. In either instrument, it is sometimes more convenient to determine the absorbance A of the species, rather than the transmission T. These are related through the Beer-Lambert equation:

• A₁₀ = - log₁₀ T 
• T = 10^-A₁₀

Although FT instruments are much less expensive and faster that dispersive instruments of the same precision, they have their own set of problems. Here's some information from the CH362 course Experimental Chemistry I at Oregon State:

The one minor drawback is that the FT instrument is inherently a single-beam instrument; it cannot use the "channel ratio" trick used in CW operation.  One result is that IR-active atmospheric components (CO2, H2O) will appear in the spectrum.  Usually, a "Background" spectrum is run, then automatically subtracted from every spectrum.  The spectrum... [above] is such a background scan.

You can see CO2 as the strong doublet [OG - due to the 'asymmetric stretch' mode] at around 2300 cm-1, and water as the "spiky" peaks in the 3800 and 1600 cm-1.  The "bell curve" shape of the spectrum reflects the output spectrum of the source:  strong in the middle, but falling off at the ends. [OG - The downward spike at about 670 cm^-1 is due to the bending mode of CO₂; notice that there is no overlap with the absorption due to water vapor in either the bending mode band or the asymmetric stretch band, so apparently Jim Diamond's assertion is demonstrably correct!]

This bending mode absorbance, although it looks insignificant in the background spectrum above, is responsible for the greenhouse gas properties of CO₂.

Outgoing spectral radiance at the top of Earth's atmosphere showing the absorption at specific frequencies and the principle absorber. For comparison, the red curve shows the flux from a classic "blackbody" at 294°K (≈21°C ≈ 69.5°F).  

It is possible, in a single measurement of the IR spectrum, to observe the rotational-vibrational spectra of all four isotopes of hydrogen chloride - ¹H³⁵Cl, ¹H³⁷Cl,²H³⁵Cl, ²H³⁷Cl. Under suitable conditions, one can see not only the rotational fine structure in the fundamental band,

but that in the first overtone as well - EIGHT different bands  - so that one can determine with great accuracy and precision five different molecular parameters for each of the four molecular isotopes:

• the harmonic vibrational frequency
• the vibrational anharmonicity - which also provides a crude estimate of the dissociation energy
• the rotational constant - from which one can determine the bond length
• the rotational-vibrational coupling constant
• the centrifugal distortion constant

For about $300, one can acquire a small (5L) lecture bottle of 99% DCl which contains both ²H³⁵Cl and ²H³⁷Cl, as well as smaller amounts of the more strongly absorbing ¹H³⁵Cl and ¹H³⁷Cl.

Problems with HCl/DCl

HCl/DCl is corrosive, so it must be shipped on land.

Packaging
5 L in steel cylinder
Shipping of this product by air freight is forbidden.
Outside of the U.S., ocean freight shipment is required and will result in substantial additional expense.
Standard 5 L quantity is packaged in a 450 mL carbon steel lecture bottle with stainless steel CGA 110/180 valve. Nominal gas pressure at 21ºC is 150 psig for 5 L . This pressure is slightly above atmospheric pressure. Care must be taken when extracting this product from the cylinder.

In addition, the empty gas cylinder must be treated as hazardous waste! This greatly inflates the cost of the experiment.

I seem to remember a couple of poster presentations about alternatives.

• Constructing a green alternative to a traditional physical chemistry experiment, the moderate-resolution infrared spectra of carbon dioxide: Analysis of weak absorption bands  

CHED 1382
Catherine Marie Clark,  and Christopher Robert Braden. Department of Chemistry, Linfield College,  McMinnville, OR 97128

In order to demonstrate the potential for CO₂ gas to replace HCl gas in a common physical chemistry experiment, FTIR spectroscopy was performed on CO₂. Techniques such as the inclusion of P₂O₅ in the gas cell were applied to reduce interference by water. This allowed for the resolution of bands resulting from rotational-vibrational coupling, which are necessary in determining molecular constants.

• Developing a green physical chemistry experiment 

I&EC 136
Christopher Robert Braden, Catherine Marie Clark, and Jim Diamond. Department of Chemistry, Linfield College, McMinnville, OR 97128

We investigated the use of CO₂ as a substitute in order to find a green alternative to a common physical chemistry experiment, the analysis of the rotational fine structure in the IR spectrum of a hydrogen halide. While HCl provides an easily analyzed spectrum with clear overtones and readily obtained isotopes, it is a corrosive substance that requires disposal as hazardous waste regardless of the method of preparation. CO₂ can be easily obtained from the atmosphere, and isotopically enriched samples are easily obtained as well. The CO₂ spectrum requires little effort to resolve and shows overtones and combination bands at moderate pressure. Though the spectrum is more complex than HCl, it is no more difficult to analyze, and the experiment provides a richer experience for undergraduates. Overall, our findings indicate that CO₂ is a safe and satisfactory substitute for HCl.

The Green Chemistry Alternative to HCl/DCl: The Rotational Fine Structure in the Fundamental Bending Mode Band of CO₂

We tried FTIR measurement of CO₂ with various methods of sample preparation, looking for a fast, easy, green alternative to HCl/DCl.

• CO₂ in the atmosphere (about 400 ppm);
• CO₂ in respired breath (about 4% by volume);
• CO₂ obtained from sublimation of dry ice pumped into an evacuated 10 cm gas cell with KBr windows at various pressures after being dried with P₂O₅.
• CO₂ obtained from sublimation of dry ice pumped into an evacuated 10 cm gas cell with KBr windows at various pressures without drying.
•  CO₂ obtained from sublimation of dry ice directly in the FTIR sample chamber without use of a cell.

The last method was easiest but the partial pressure of CO₂ was unknown. Given the lack of overlap between water vapor and CO₂ absorption bands [see above],we settled on measuring CO₂ obtained from sublimation of dry ice pumped into an evacuated 10 cm gas cell with KBr windows at various pressures without drying. A partial pressure of 100 torr provided strong, sharp spectra.

The FTIR Spectrum of CO₂

Here are the actual results of a set of experiments from 2007.

FTIR Spectrum of CO₂(g) from 370 cm^-1 to 7000 cm^-1

All of the "negative" absorbances represent absorption of water vapor in the background spectrum, weaker stronger than absorption of water vapor in the sample spectrum. From right to left, the observed bands represent:

1. poor transmission of the KBr windows below 400 1/cm
2. water vapor absorption between 400 and 500 1/cm
3. the bending mode band,between 500 and 750 1/cm
4. water vapor absorption, between 1300 and 2000 1/cm 
5. the asymmetric stretch band, between 2200 and 2400 1/cm
6. the only overlapping band in this spectrum, showing both  CO2 absorption and water vapor,  between 3400 and 4000 1/cm
7. a very weak combination band of CO2 between 4800 1/cm to 5200 1/cm
8. weak water vapor absorption, between 5200 and 5600 1/cm
9. gradual attenuation of the signal above 6000 1/cm due to both windows and detector.

Some of the features in the bending mode band are visible only with higher resolution.





Bending mode band, from 500 cm^-1 to 750 cm^-1

Besides the prominent Q band in the center, the other features are: a Fermi resonance to the high-energy (left) side of the Q band; the weaker (1.1%) 13CO2 Q band; the low-energy component of the Fermi resonance in the CO2 band; and emergence of the the low-energy component of the Fermi resonance in 13CO2. There are many lines present in the rotational fine-structure.

Here is an interesting zoom into the combination band, show the absorption spectrum (in black), and its second derivative (in blue). Note that absorption maxima correspond to minima in the second derivative. 

 

A linear regression of peak position versus a cubic function of an index related to the rotational quantum number is sufficient to determine the molecular parameters described above with a great deal of precision. There is about a 1/3 chance that there is a significant difference in B0 and r0 between this result and that of Herzberg. The band origins are, on the other hand, significantly different, but we had a laser.

Not too bad, considering we were working with data that is demonstrably false!