Articles written in Pramana – Journal of Physics

    • Permeability of hydrogen in two-dimensional graphene and hexagonal boron nitride sheets


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      We study the permeability of atomic hydrogen in monolayer hexagonal boron nitride (h-BN) and graphene using first-principles density functional theory-based simulations. For the specific cases of physisorptionand chemisorption, barrier heights are calculated using the nudged elastic band approach. We find that the barrier potential for physisorption through the ring is lower for graphene than for h-BN. In the case of chemisorption, we have studied three specific cases where the H atom passes through by making bonds with the atoms at different sites in the ring. The chemisorption barrier height for graphene is found to be, in general, higher than that of h-BN. We conclude that the dominant mechanism of tunnelling through the graphene sheet and h-BN sheets would be physisorption and chemisorption, respectively.

    • Photon-induced low-energy nuclear reactions


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      We propose a new mechanism for inducing low-energy nuclear reactions (LENRs). The process is initiated by a perturbation which we assumed to be caused by absorption or emission of a photon. Due to the electromagnetic perturbation, the initial two-body nuclear state forms an intermediate state to make a transition into the final nuclear state through the action of another perturbation. In the present paper,we take the second perturbation to be also electromagnetic. We need to sum over all energies of the intermediate state. Since the upper limit on this sum is infinity it is possible to get contributions from very high energies for which the barrier penetration factor is not too small. By considering a specific reaction, we determine the conditions under which this mechanism may lead to significantly enhanced reaction rates. We find that the mechanism leads to very small cross-sections in free space. However, in a condensed medium, there exist several possibilities leading to enhanced cross-sections, which may lead to observable reaction rates even at relatively low energies. Hence we argue that LENRs are possible and provide a theoretical set-up which may explain some of the experimental claims in this field.

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