François Lapointe

François Lapointe
National Research Council Canada | NRC

PhD

About

27
Publications
2,582
Reads
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588
Citations
Introduction
Materials scientist with a background in physical chemistry and interests in nanomaterials, sensors, electrochemistry and spectroscopy.
Additional affiliations
June 2016 - present
National Research Council Canada
Position
  • Research Associate
May 2014 - May 2016
Fritz Haber Institute of the Max Planck Society
Position
  • PostDoc Position
September 2007 - May 2014
Université de Montréal
Position
  • PhD Student

Publications

Publications (27)
Article
We report anomalous antiresonances in the infrared spectra of doped and disordered single layer graphene. Measurements in both reflection microscopy and transmission configurations of samples grafted with halogenophenyl moieties are presented. Asym- metric transparency windows at energies corresponding to phonon modes near the Γ and K points are ob...
Article
Full-text available
Quantitative description of reaction mechanisms in aqueous phase electrochemistry requires experimental characterization of local water structure at the electrode/aqueous interface and its evolution with changing potential. Gaining such insight experimentally under electrochemical conditions is a formidable task. The potential-dependent structure o...
Article
Full-text available
Raman spectroscopy uses visible light to acquire vibrational fingerprints of molecules, thus making it a powerful tool for chemical analysis in a wide range of media. However, its potential for optical imaging at high resolution is severely limited by the fact that the Raman effect is weak. Here, we report the discovery of a giant Raman scattering...
Article
Full-text available
This work revisits the physics giving rise to the carbon nanotubes phonon bands in the mid- infrared. Our measurements of doped and undoped samples of single-walled carbon nanotubes in Fourier transform infrared spectroscopy show that the phonon bands exhibit an asymmetric lineshape and that their effective cross-section is enhanced upon doping. We...
Article
Much like with organic semiconductor FETs, a characteristic of carbon nanotube based devices has been their almost exclusive p-type character in air. Electron transport can be observed only under certain conditions, for instance devices annealed in vacuum. We investigated the impact of the chemical nature of the substrate and of ambient adsorbates...
Article
Full-text available
SWCNT-based thin-film transistors (TFTs) typically display unipolar p-type electrical characteristics in ambient condition due to the O2/H2O redox couple. However, complementary circuits that combine both p and n channels are preferred due to lower power requirements. Typical approaches with small molecule or polymeric dopants often yield ambipolar...
Article
The essential part of electrochemistry is charge transfer. To understand this process in great detail, one needs to probe the relevant kinetics and dynamics on time scales spanning from femtoseconds to seconds or even longer. While a conventional electrochemical detection scheme is sufficient for nanosecond or slower processes, it does not offer hi...
Article
Full-text available
The lack of efficient optical components operating with terahertz (THz) radiation is a limiting step in the ongoing large-scale development of this technology in fields such as telecommunication and imaging. In this work, we propose the use of double-walled carbon nanotube (DWCNT) films as the active electrode in THz modulation devices. Using six b...
Article
Full-text available
The hydrated electron has fundamental and practical significance in radiation and radical chemistry, catalysis and radiobiology. While its bulk properties have been extensively studied, its behavior at solid/liquid interfaces is still unclear due to the lack of effective tools to characterize this short-lived species in between two condensed matter...
Article
High purity semiconducting single-walled carbon nanotubes (sc-SWCNTs) are promising for portable and high sensitivity gas sensors due to their excellent physical and electrical properties. Here we describe the synthesis of a novel indigo-fluorene based copolymer (PFIDBoc) that has been designed to selectively enrich sc-SWCNTs with excellent purity...
Preprint
The hydrated electron has fundamental and practical significance in radiation and radical chemistry, catalysis and radiobiology. While its bulk properties have been extensively studied, its behavior at buried solid/liquid interfaces is still unclear due to the lack of effective tools to characterize this short-lived species in between two condensed...
Article
The high sensitivity of carbon nanotube devices as gas sensors is generally attributed to the large surface area of the material, whereas selectivity is often imparted by the “lock-and-key” mechanism. In contrast with this picture, where little function is conferred to the underlying substrate, we demonstrate that bottom gate carbon nanotube networ...
Article
Although carbon nanotube transistors present outstanding performances based on key metrics, large-scale uniformity and repeatability required in printable electronics depend greatly on proper control of the electrostatic environment. Through a survey of polymer dielectric encapsulants compatible with printing processes, a simple correlation is foun...
Article
Nanomaterials are ideal for electrochemical biosensors, with their nanoscale dimensions enabling the sensitive probing of biomolecular interactions. In this study, we compare field-effect transistors (FET) comprised of unsorted (un-) and semiconducting-enriched (sc-) single-walled carbon nanotubes (SWCNTs). un-SWCNTs have both metallic and semicond...
Article
Golden gaze persuades. Hydrophobic water molecules were detected at the gold electrode/aqueous electrolyte interface using interface-specific vibrational sum frequency spectroscopy. In their Communication (DOI: 10.1002/anie.201612183), R. K. Campen et al. explain that the population and structure characteristics of this water type are bias dependen...
Article
Quantitative description of reaction mechanisms in aqueous phase electrochemistry requires experimental characterization of local water structure at the electrode/aqueous interface and its evolution with changing potential. Gaining such insight experimentally under electrochemical conditions is a formidable task. The potential-dependent structure o...
Article
Liquid phase encapsulation of α-sexithiophene (6T) molecules inside individualized single-walled carbon nanotubes (SWCNTs) is investigated using Raman imaging and spectroscopy. By taking advantage of the strong Raman response of this system, we probe the encapsulation isotherms at 30°C and 115°C using a statistical ensemble of SWCNTs deposited on a...
Preprint
Full-text available
Herein, valley physics is exploited to account for anomalous bands in the infrared spectra of doped and disordered single layer graphene. We present infrared spectroscopy measurements of graphene grafted with iodophenyl moieties in both reflection microscopy and transmission configu- rations. Asymmetric signals at energies corresponding to phonon m...
Thesis
Full-text available
Carbon nanotubes and graphene are sp2 hybridized carbon nanostructures which electrical and optical properties raise considerable interest for the design of a new generation of electronic devices and optically active materials. However, many challenges remain before their implementation in industrial processes on a large scale. Materials chemistry,...
Conference Paper
Covalent chemistry on carbon nanotubes generates useful and stable functionalities, but it also generally damages their electronic properties, which is a critical drawback for device applications. Here we present two approaches to achieve covalent functionalization of carbon nanotubes without compromising on their electronic properties. For each ca...
Article
Double-walled carbon nanotubes (DWNTs) present an original coaxial geometry in which the inner wall is naturally protected from the environment by the outer wall. Covalent functionalization is introduced here as an effective approach to investigate DWNT devices. Performed using an aryldiazonium salt, the functionalization is reversible upon thermal...
Conference Paper
Double-walled carbon nanotubes (DWNT) present a particular geometry in which the inner wall is isolated by the outer wall, while the latter is in direct interaction with the environment. Here, we studied optical and electrical properties of functionalized DWNT derivatives (f-DWNT) prepared by aryldiazonium reactions. We first present absorption spe...
Article
Orientation relaxation in miscible poly(vinyl phenol) (PVPh)–poly(ethylene oxide) (PEO) blends (from 25 to 40wt% PEO) was investigated using polarization modulation infrared linear dichroism. This blend was selected to study the effect of strong hydrogen bonds on relaxation. The results show that PEO is more oriented than PVPh, and remains so throu...

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Projects

Project (1)
Project
Employ modern spectroscopic methods, i.e. vibrational sum frequency spectroscopy, to study fundamental electrochemical problems including i). water structure at the electrode/solution interface; ii). Noble metal electrochemical oxidation; iii). ultra-fast photo-voltage & photo-current detection.