The discussion centers on the feasibility of using resonance to dissociate carbon dioxide (CO2) into carbon and oxygen. Participants clarify that sound waves, which operate at frequencies up to a few MHz, cannot achieve the necessary energy levels for molecular bond dissociation, which requires optical frequencies in the terahertz range. The conversation highlights that while laser light can effectively break molecular bonds, achieving this requires precise frequency control and understanding of molecular vibrations. Resources such as the infrared spectrum and literature on atomic and molecular physics are recommended for further exploration.
PREREQUISITESChemists, physicists, and researchers interested in molecular dissociation techniques, particularly those exploring the use of laser technology for bond breaking in chemical compounds.
Yes, exactly. I`m thinking about the dissociation of the nucleus of, for example, CO2 into Carbon and oxygen. Hope it makes senseDrClaude said:You mean to dissociate a molecule?
If so, what resonance are you thinking about?
You mean, how I intend to create the resonance itself? Sound, very high frequency.DrClaude said:You haven't said what resonance you are thinking about.
If the input frequency matches the frequency of self-oscillation of the bond between C and O, then, why not? Any ideas as to, where to find the frequencies of bonds between certain elements or how to calculate them?DrClaude said:You can't use sound to break a molecule like CO2.
Same idea:DrClaude said:You can't use sound to break a molecule like CO2.
Even if you could do that in theory, molecular vibrations are highly non-linear, so there isn't a single frequency you could excite at. And the link you gave talks about using laser light, which is not the same thing! Even then, simply vibrationally exciting a molecule at a single frequency won't work, but time-varying frequencies are needed.Sveral said:If the input frequency matches the frequency of self-oscillation of the bond between C and O, then, why not? Any ideas as to, where to find the frequencies of bonds between certain elements or how to calculate them?
Sveral said:If the input frequency matches the frequency of self-oscillation of the bond between C and O, then, why not? Any ideas as to, where to find the frequencies of bonds between certain elements or how to calculate them?
That is a point even one with my...knowledge can understand, well put.f95toli said:Also, just think of the wavelength of sound compared to the size of the molecule.
Ok, but what about the link I posted? It should mean, that it is doable with light...f95toli said:There are several reasons. One is that frequencies involved in molecules are optical, i.e. a few THz at the very least. "Sound" in the usual sense of the word only goes up to a few MHz at most (for ultrasound).
Much appreciated for the information. Thank you.DrClaude said:Even then, simply vibrationally exciting a molecule at a single frequency won't work, but time-varying frequencies are needed.
It is done all the time with light. People have been working for decades now on breaking specific bonds in molecules.Sveral said:Ok, but what about the link I posted? It should mean, that it is doable with light...
Ok, but any ideas as to how to calculate the resonant frequency of a bond of C-O? Also are there any DIY verions of wideband light generation chips or something?DrClaude said:It is done all the time with light. People have been working for decades now on breaking specific bonds in molecules.
Sveral said:Ok, but any ideas as to how to calculate the resonant frequency of a bond of C-O?
I don't think that the equipment needed to do this is within reach of a layman.Sveral said:Also are there any DIY verions of wideband light generation chips or something?
Thank you for all of the useful information.DrClaude said:The easiest is to look at the infrared spectrum http://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Type=IR-SPEC&Index=1I don't think that the equipment needed to do this is within reach of a layman.
easier to measure it by observing the color of the laser light. Or more quantitatively, measuring the distance between fringes in an interference patternSveral said:Any ideas as to, how one can calculate the output frequency of a laser diode by knowing the type of semiconductors used?
Solid answer, but seems like I need to specify the question. If I know everything about every component that`ll be used for the building of the laser, how can I calculate the frequency using those numbers?Ben Wilson said:easier to measure it by observing the color of the laser light. Or more quantitatively, measuring the distance between fringes in an interference pattern
Buy a laser where they tell you the frequency on the box. I think the calculations you want to do are very complex. But there may be simpler method that I've missed.Sveral said:Solid answer, but seems like I need to specify the question. If I know everything about every component that`ll be used for the building of the laser, how can I calculate the frequency using those numbers?
Sveral said:Any ideas as to, how one can calculate the output frequency of a laser diode by knowing the type of semiconductors used?
A. K. A. It's far from simple or DIY...f95toli said:You can't. The laser frequency will depend on the details of the device design and the choice of material is only one of several factors. Laser diodes are complex devices built up of many semiconductor layers with different composition; there are also many different ways to make a laser diode (a InGaAs based VCSEL is very different from the "classical" red Si based diode).
Hence, you need to either measure it or just read the datasheet.
I would like to point out that in this case, the molecule dissociates due to electronic excitation, not vibrational excitation.Nino MMP said:You might enjoy looking up the HCl canon. It's a physical chemistry experiment with H2 and Cl2 in a container; it demonstres how a certain wavelength is needed to break a bond of diatomic chloride, forming HCl and a 'canon' effect.
This will be covered in some books on atomic and molecular physics, but it is getting closer to chemistry than to physics.Nino MMP said:Oh okay, thank you for the correction DrClaude! Would atomic/optical books be best to read into this more? I am intrigued.
Ok, will do, thanks.Nino MMP said:You might enjoy looking up the HCl canon. It's a physical chemistry experiment with H2 and Cl2 in a container; it demonstres how a certain wavelength is needed to break a bond of diatomic chloride, forming HCl and a 'canon' effect.
E=h (nu) where nu is frequency and nu or sometimes f=v/lambda where v here would be the speed of light. Play with these and the energy of a CO2 bond (typically in kJ/mol - there's tables for it anywhere from google). That paired with the typical wavelength for sound help explain why that wouldn't really work. There are plenty of E/M wavelengths that will break the bond in question, though.
Actually useful, not too late.blue_leaf77 said:May be too late to reply but as I recall to reach the first dissociation limit of CO2 to become CO and O, you need around 7.5 eV photon energy. You will need laser in the UV range to do this dissociation.
I looked for the HCl cannon, but couldn`t seem to find it. Any chance you could toss in a link?Nino MMP said:Ah okay great! Yep, unfortunately my passion seems to repeatedly be right at the interface of the physical sciences. Thank you, sir.