New Molecules for a Faster Internet

Roland Piquepaille writes "An international team of researchers has discovered a new generation of optical molecules which interact 50% more strongly with light than any molecules ever tested. These organic molecules, known as chromophores, have been theorized by physicists at Washington State University, synthesized by chemists in China and tested for their actual optical properties by chemists in Belgium. But if they're excellent candidates for being used in optical technologies such as optical switches and Internet connections, these new materials should not be used before several years — if ever. Read more for additional details and a picture of the physicist who broke a law he established in 1999."

Comments

Off Topic, No Guilt

[rohar]

I love love articles like this, submitted by the author as links to their own blog. I don't feel guilty about posting off-topic links to articles I wrote.

Some New Ideas in Indirect Solar Electrical Power Generation, Clean Water Capture and Seasonal Heat Storage

Re:Similarly confused...

[kebes]

The summary and Roland's article (not surprisingly?) get the details about these 'limits' somewhat wrong. If you read the intro to the arXiv article (warning: PDF), they say:

Quantum cal-culations using sum rules have been used to place an upper-bound on the molecular susceptibilities; [1, 2, 3, 4] but, the largest nonlinear susceptibilities of the best molecules fall short of the fundamental limit by a factor of 10^(3/2).[4, 5] A thorough analysis shows that there is no reason why the molecular hyperpolarizability can not exceed this apparent limit.[6] In this letter, we report on a novel set of molecules where the one with modulated conjugation[7] is found to have a hyperpolarizability that breaches the apparent limit.

If you look up reference [4], which you can find here, you see this is an "Erratum" (publication pointing out a mistake you made in a previous publication). In it, he shows (see graph), that what he previously plotted as the "limit" was a plotting mistake (not a theoretical mistake). So what he claims is that there is a fundamental (quantum) limit, but there is also an "apparent limit" based on the accumulated experimental data on chromophores so far.

Thus, this new paper is claiming to have broken through an "apparent limit" that existed before. Nothing fundamental about this limit, of course... it was merely that synthetic chemists had yet to be able to create molecules that good. This new report is a 'breakthrough' in the sense that they've made molecules with still higher nonlinear susceptibilities. (But still not violating the theories...)

Will this ever show up in real technology? Probably not. In 'real devices' of course having good optical response is only half the challenge. It must also be cheap enough, stable enough, easy to process, etc. So it's a step forward, but I would call it's more a 'pushing the edge of what can be synthesized' rather than a 'telecom breakthrough' as Roland tries to spin it.

Telescopes?

[AtariDatacenter]

I wonder... could this make a higher transmissive reflective coating for telescopes?

Re:Telescopes?

[Anonymous Coward]

You are correct that a molecule could be designed to emit light at one energy at the expense of transmission of light at another energy. However, optical coatings used for telescopes tend to be designed with materials which adhere well to the lens and can produce nearly atomically flat layers by processes such as sputtering or molecular beam epitaxy etc. (google epitaxial growth to read up on this). However, the quantum yield (efficiency) of many chromophores is fairly low (quantum dots are the leaders here) and application to glass would be difficult. As an aside, quantum dots tend to absorb a wide range of energy and emit at one wavelength, thus integrating a wide field of spectral energy which is emitted at a single primary energy. Since quantum dot emission is highly tunable by physical dimension alone, they might be a better candidate for some sort of novel application along the lines which you are thinking. Sure you could experiment with the referenced chromophores, but I would expect the optical clarity to be more adversely affected than any improvement that might be realized from optical activity, that is, unless you have a chromophore that absorbs/emits just where is needed. In my case, by analyzing the emitted light I am able to identify nearby molecules due to the specific changes in particular resonance modes which are perturbed by multi-molecular interactions between the chromophore and nearby adsorbate. Thus chromophores are useful for all sorts of things, such as molecular recognition. But honestly, I'm not waiting for Roland to opine on the subject. Let's hope that greasemonkey script mentioned below gets adopted into the slash code ASAP.

Greasemonkey script to remove piquepaille stories

[viking80]

Here is one of many scripts:
http://userscripts.org/scripts/show/5735/

Phenazopyridine

[MillionthMonkey]

I used to work as an analytical chemist in a place that made phenazopyridine tablets, which are sold under the brand name Pyridium. This stuff is prescribed for women with urinary tract infections, and acts as a urinary analgesic.

Phenazopyridine has an aromatic azo -N=N- bond in it that exists in resonant conformation between a benzene ring and a pyridine ring. Azo bonds impart strong red-orange-yellow colors, and in pure form phenazopyridine is a dark red powder. It's only slightly soluble in water, but it really likes alcohols and the standard solvent in most lab procedures was methanol. And you have to use alcohol for everything with this stuff- you'll end up spraying alcohol everywhere and wiping stuff down with alcohol multiple times. Saturated alcoholic solutions are dark reddish-orange, but in lower concentrations the color fades to dark orange and then light orange before settling on a powerful yellow at extremely low concentrations that gives everything a just-pissed-on look. The tiniest speck could probably turn an Olympic swimming pool a noticeable yellow. In alcohol the yellow stain is really mobile, and a major way it gets around is when people try to clean it. The alcohol turns into yellow ink that gets everywhere. But you can't use water because that will set the stain.

All the hallways had fuzzy yellow lines running down their centers because people were tracking phenazopyridine around. The copy machine, the doorknobs, the tables, the balances, books, papers, sinks, everything- it all picked up a faint yellow sheen. You'd see a yellow tinge along the edges of things, and soon stuff at your house would pick up a yellow tinge. I haven't worked at that place for over a decade and I still have a few yellow-tinged items around.

The major side effect when taken for urinary tract infections is dark orange urine. Make sure to close the lid when you flush or your house might turn yellow. For that matter, your blood is now a powerful yellow dye so be careful if you bleed in the house. You can't wear contact lenses either because your corneas will stain them yellow. And avoid Olympic swimming pools I guess.

I heard an interesting phenazopyridine story recently, from someone who had a friend taking it for a UTI. She thought her urine was so pretty that she decided to stain her hair orange for Halloween with one of her tablets. Which worked, until she tried to wash it out. I can't imagine what that scene must have been like, but without an alcoholic shower it sounds pretty hopeless. She ended up shaving her head.