Steam from IR radiation by classical heat transfer?

PITTSBURGH - May 9, 2017 - PRLog -- .
Introduction
Light absorbing NPs immersed in water and illuminated by IR light are found [1] capable of generating steam without the necessity of heating the entire fluid volume. NPs stand for nanoparticles. The NP separations in water are unlikely to be less than a few microns suggesting the NPs are optically and thermally isolated from each other as EM confinement requires NP spacings less than the wavelength of the IR photons. EM stands for electromagnetic. Moreover, the temperature increase at the surface of the NPs is known [2] to not exceed nominal water temperatures and cannot produce steam. In this arrangement, light trapping by NPs is proposed [3] to produce steam as IR light is absorbed and scattered passing through a random ensemble of NPs, the validity of which is thought confirmed based on classical MC simulations. MC stands for Monte-Carlo.

But QM governs the nanoscale and not classical physics. QM stands for quantum mechanics. Classical MC assumes the NPs have heat capacity, or kT energy. By the Planck law of QM, however, NPs having high S/V ratios place the NP atoms under high EM confinement thereby precluding the heat capacity necessary for NPs to increase in temperature. S/V stands for surface-to-volume. Hence, NP temperatures cannot increase above nominal water temperature that suggest MC simulations of steam generation from IR radiation in NP dispersions are meaningless.

But if so, how do NPs conserve IR laser heat?

Proposed Mechanism
Since IR laser heat cannot be conserved by increasing NP temperatures, QED conserves the surface heat in NPs by creating EM radiation having half-wavelength λ/2 = d standing across the diameter d of the NP. QED stands for quantum electrodynamics, but is a simple form of the complex light-matter interaction proposed by Feynman and others. By simple QED, EM radiation is created from surface heat having Planck energy E = hν, i.e., h is Planck's constant and ν is frequency, ν = (c/n) / λ = c/2nd, where the velocity of light c is corrected for the slower speed in the solid state by the refractive index n of the NP. Once the NP surface heat is expended in forming the standing waves, the EM confinement vanishes and the QED induced photon escapes into the water. See diverse QED applications of the Planck law at the nanoscale at http://www.nanoqed.org/, 2010 – 2017.

Application
The application of QED induced EM radiation in NPs having d < 100 nm is illustrated in the thumbnail which shows the wavelength dependence of the absorption of water. The inset shows the IR laser directed downward in the direction of gravity onto the surface of liquid water causes a vertical temperature gradient that induces natural convection in the water showing the NPs (black circles) to aggregate at the air-water interface. IR laser heat absorbed by the NPs is shown to be induced by QED to produce EUV radiation. EUV stands for extreme ultraviolet.

The usual 80 nm silicate NPs have n = 1.5 produce UV at λ = 240 nm which the thumbnail shows is far less absorbent in water than in the IR at λ = 808 nm. But the test [3] were performed with scattering NPs that are small with respect to wavelength of light and textured to be optically soft having n = 1. Hence, the scattering NPs emit EUV radiation at λ = 160 nm. The thumbnail shows water absorption in the EUV is 4 orders of magnitude greater than the IR at 808 nm. What this means is the IR heat absorbed by the NPs is very efficiently absorbed in water, thereby significantly increasing the local water temperature to explain the production of steam at the air-water interface.

Conclusions
QM by the Planck law precludes absorbed IR laser heat from increasing NP temperatures. Instead, NPs conserve IR laser heat by QED inducing EM radiation standing across the NP diameter. For scattering NPs, EUV radiation is produced that is efficiently absorbed in water allowing high temperatures to be created to explain the formation of steam at the air-water interface.

Unfortunately, the Planck law of QM known for over a century old is ignored today by the nanotechnology community. Indeed, the number of citations in [1 – 3] exceeding 50,000 shows the fake news that classical physics explains heat transfer in NPs is widespread, the consequence of which may have legal consequences for researchers who claim NPs are safe in medical applications, e.g., the claim NPs in the treatment of cancer are safe because cancer is killed by otherwise benign high temperatures when in fact the cancer is actually killed by the UV emitted from the NPs. What this means is the NPs cause collateral DNA damage to adjacent tissure that if not repaired by the immune system may, in and of itself cause future cancers.

References
[1] O. Neumann, et al., "Solar Vapor Generation Enabled by Nanoparticles," ACS Nano, 7, 42−49 ,2013.
[2] S. V. Boriskina, et al., "Plasmonic Materials forEnergy: From Physics to Applications, Mater. Today, 16, 375−386, 2013.
[3] N. J. Hogan, et al., "Nanoparticles Heat through Light Localization," ACS Nano Letters, dx.doi.org/10.1021/nl5016975, 2014.