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Chemistry in confined phases by Quantum Mechanics
Chemistry based on statistical mechanics suggesting chemical reactions are enhanced by very high pressure inside nanopores is superseded by photochemical enhancement from QED radiation finding basis in quantum mechanics
Phenomena that occur at very high pressures - thousands or tens of thousands of atmospheres - are often thought observed [1, 2] at atmospheric pressure in nanopores. Most notable is the nitric oxide dimer reaction 2NO ↔ (NO)(NO) having a dimer yield of less than 1 % at atmospheric pressure, but in nanopores or carbon nanotubes the yield is almost 100% as confirmed by magnetic susceptibility measurements. Assuming the dimers form under pressure, simple thermodynamic calculation shows that yields near 100 % can only occur at pressures of about 14,000 atmospheres – even though the open ends of the confined spaces are exposed to atmospheric pressure !!! Nevertheless, MD and MC simulations based on statistical mechanics confirm high pressure is the mechanism of producing the enhanced dimer yields. MD stands for Molecular Dynamics and MC for Monte-Carlo.
MD and MC simulations based on statistical mechanics assume atoms in the confined phase have classical kT thermal heat capacity. The thumbnail gives the pressure P as computed [1, 2] by statistical mechanics. In contrast, QM by the Planck law restricts the atom heat capacity depending on its EM confinement. QM stands for quantum mechanics and EM for electromagnetic. Atoms in nanopores of a few nanometers in diameter are therefore under high EM confinement, and therefore have vanishing thermal kT heat capacity. Hence, the pressure P also vanishes. What this means is high pressures of 14,000 atmospheres, or the like, do not exist in nanopores and enhanced nitric oxide dimer yield is caused by another mechanism.
Since atoms under EM confinement lack heat capacity, the energy ΔU cannot be conserved by the usual increase in temperature. Instead, conservation proceeds by the creation of non-thermal QED induced EM waves standing across the pore diameter. QED stands for quantum electrodynamics. The QED radiation wavelength λ is, λ = 2 nd, where d is the pore diameter and n the refractive index of the gases. In nanopores having diameters d of a few nanometers, the QED radiation produced in the EUV and beyond is more than sufficient to alter the chemistry of the gases by photolysis. EUV stands for extreme ultraviolet. Hence, nitrogen oxide dimer yield is proposed enhanced by photochemical mechanisms which may readily be confirmed by EUV spectroscopy. See diverse QED applications at http://www.nanoqed.org, 2010 - 2015.
Over the past decade, diverse chemical phenomena observed for confined nanophases and interpreted by high pressures may be more credibly explained by EUV photochemistry briefly summarized as follows.
1. High Pressure Phases Liquid-solid transitions  between atomically-smooth mica surfaces at temperatures well above normal melting points of cyclohexane and n-dodecane may be explained by bond disruption under EUV radiation
2. Interlayer Atomic Spacing Experimental small-angle X-ray scattering studies  that show significant effects of the adsorption of a confined nanophase on the pore width are characteristic of computer chip etching in EUV lithography.
3. Melting of Water In confined water, the conflict  between the energetic minimization of the hydrogen bond network and pore geometry is resolved as the hydrogen bonds are broken by EUV radiation.
QM and not statistical mechanics governs our understanding of chemistry in confined nanophases.
QM denies atoms heat capacity in the nanophase. Energy conservation proceeds by creating QED radiation in the EUV and beyond that by photolysis alters the chemistry of the contained gases and nanophase surfaces.
Although dissociation of chemical bonds of gases is spontaneous in the nanophase, recombination is also prompt. In the nanophase, gases constantly fluctuate between ionization and de-ionization.
 Y. Long, et al., “Pressure enhancement in carbon nanopores,” Chem. Chem. Phys., 13, 17163–17170, 2011.
 Y. Long, et al., “On the molecular origin of high-pressure effects in nanoconfinement:
 M. F. Chaplin, "Structuring and behaviour of water in nanochannels and confined dsorption and Phase Behaviour in Nanochannels and Nanotubes," L. Dunne and G. Manos, Ed. Springer, 241-255, 2009.