laboratoire de physique statistique
laboratoire de physique statistique


Scaling Behavior for Ionic Transport and its Fluctuations in Individual Carbon Nanotubes - Secchi, Eleonora and Nigues, Antoine and Jubin, Laetitia and Siria, Alessandro and Bocquet, Lyderic

Abstract : In this Letter, we perform an experimental study of ionic transport and current fluctuations inside individual carbon nanotubes (CNTs). The conductance exhibits a power law behavior at low salinity, with an exponent close to 1/3 versus the salt concentration in this regime. This behavior is rationalized in terms of a salinity dependent surface charge, which is accounted for on the basis of a model for hydroxide adsorption at the (hydrophobic) carbon surface. This is in contrast to boron nitride nanotubes which exhibit a constant surface conductance. Further, we measure the low frequency noise of the ionic current in CNTs and show that the amplitude of the noise scales with the surface charge, with data collapsing on a master curve for the various studied CNTs at a given pH.
Massive radius-dependent flow slippage in carbon nanotubes - Secchi, Eleonora and Marbach, Sophie and Nigues, Antoine and Stein, Derek and Siria, Alessandro and Bocquet, Lyderic
NATURE 537210-213 (2016) 

Abstract : Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces(1-4). These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting(5-10), yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated(11,12) because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far(13). This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes(7-9,14-17), none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube(11). Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.
Chemisorption of Hydroxide on 2D Materials from DFT Calculations: Graphene versus Hexagonal Boron Nitride - Grosjean, Benoit and Pean, Clarisse and Siria, Alessandro and Bocquet, Lyderic and Vuilleumier, Rodolphe and Bocquet, Marie-Laure

Abstract : Recent nanofluidic experiments revealed strongly different surface charge measurements for boron-nitride (BN) and graphitic nanotubes when in contact with saline and alkaline water (Nature 2013, 494, 455-458; Phys. Rev. Lett. 2016, 116, 154501). These observations contrast with the similar reactivity of a graphene layer and its BN counterpart, using density functional theory (DFT) framework, for intact and dissociative adsorption of gaseous water molecules. Here we investigate, by DFT in implicit water, single and multiple adsorption of anionic hydroxide on single layers. A differential adsorption strength is found in vacuum for the first ionic adsorption on the two materials-chemisorbed on BN while physisorbed on graphene. The effect of implicit solvation reduces all adsorption values, resulting in a favorable (nonfavorable) adsorption on BN (graphene). We also calculate a pK(a) similar or equal to 6 for BN in water, in good agreement with experiments. Comparatively, the unfavorable results for graphene in water echo the weaker surface charge measurements but point to an alternative scenario.
Ultra-sensitive flow measurement in individual nanopores through pressure - driven particle translocation - Gadaleta, Alessandro and Biance, Anne-Laure and Siria, Alessandro and Bocquet, Lyderic
NANOSCALE 77965-7970 (2015) 

Abstract : A challenge for the development of nanofluidics is to develop new instrumentation tools, able to probe the extremely small mass transport across individual nanochannels. Such tools are a prerequisite for the fundamental exploration of the breakdown of continuum transport in nanometric confinement. In this letter, we propose a novel method for the measurement of the hydrodynamic permeability of nanometric pores, by diverting the classical technique of Coulter counting to characterize a pressure-driven flow across an individual nanopore. Both the analysis of the translocation rate, as well as the detailed statistics of the dwell time of nanoparticles flowing across a single nanopore, allow us to evaluate the permeability of the system. We reach a sensitivity for the water flow down to a few femtoliters per second, which is more than two orders of magnitude better than state-of-the-art alternative methods.
Dynamical backaction cooling with free electrons - Nigues, A. and Siria, A. and Verlot, P.

Abstract : The ability to cool single ions, atomic ensembles, and more recently macroscopic degrees of freedom down to the quantum ground state has generated considerable progress and perspectives in fundamental and technological science. These major advances have been essentially obtained by coupling mechanical motion to a resonant electromagnetic degree of freedom in what is generally known as laser cooling. Here, we experimentally demonstrate the first self-induced coherent cooling mechanism that is not mediated by an electromagnetic resonance. Using a focused electron beam, we report a 50-fold reduction of the motional temperature of a nanowire. Our result primarily relies on the sub-nanometre confinement of the electron beam and generalizes to any delayed and spatially confined interaction, with important consequences for near-field microscopy and fundamental nanoscale dissipation mechanisms.