|Lasers! (Image from Wikipedia)|
|This single crystal diamond was grown by CVD (from Wikipedia)|
There are a number of different kinds of reactors that can perform CVD reactions. The ones I am most familiar with, from using them at Michigan State, are microwave plasma reactors. In a future post I hope to describe the MSU reactors better, but for now I'll just briefly mention some of the most common types of microwave reactors, just noting here that there are other kinds, and the one I have used is not one of the ones pictured below.
|This Figure, from , shows four common types of CVD reactor: (a) Hot Filament Reactor (b) 'NIRIM' type Microwave Plasma Reactor (c) 'ASTEX' type Microwave Plasma Reactor (d) DC Arc Jet Plasma Torch Reactor|
|Diagram of the setup of the Arc Jet diamond deposition system, with a CO2 laser added to enhance the growth process, Figure from |
By using exactly the right frequency, the glass moves in sync with the sound waves. In a similar way, molecules can move in resonant modes when they are hit with light waves of exactly the right frequency. In fact, there are a number of different types of these modes, where the hydrogens on a hydrocarbon move in a patterned way with each other:
|Vibrational modes of the methylene group, from the UC Davis Chem Wiki|
|The absorption for different laser wavelengths, from |
|polycrystalline diamond films grown with different enhancement laser wavelengths, from |
So, as for our original questions, I think I've shown how laser light could improve the growth process, and that maybe this technique could have some potential for improving diamond growth in general!
 Xie, Z., Bai, J., Zhou, Y., Gao, Y., Park, J., Guillemet, T., Jiang, L., Zeng, X., & Lu, Y. (2014). Control of crystallographic orientation in diamond synthesis through laser resonant vibrational excitation of precursor molecules Scientific Reports, 4 DOI: 10.1038/srep0458
 May, P. (2000). Diamond thin films: a 21st-century material Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 358 (1766), 473-495 DOI: 10.1098/rsta.2000.0542
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