Christophe Humbert

Christophe Humbert
Université Paris-Saclay · Institut de Chimie Physique

Dr HDR

About

87
Publications
11,600
Reads
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1,529
Citations
Additional affiliations
October 2020 - present
French National Centre for Scientific Research
Position
  • Managing Director
January 2006 - September 2020
French National Centre for Scientific Research
Position
  • Research Associate
January 2006 - present
Université Paris-Sud 11
Position
  • CNRS Researcher

Publications

Publications (87)
Article
Full-text available
In this Special Issue, invited researchers elaborate on ‘Recent Advances in Linear and Nonlinear Optics’, demonstrating how sensitive light–matter interactions are concerning symmetry [...]
Article
Full-text available
Nonlinear plasmonics requires the use of high-intensity laser sources in the visible and near/mid-infrared spectral ranges to characterise the potential enhancement of the vibrational fingerprint of chemically functionalised nanostructured interfaces aimed at improving the molecular detection threshold in nanosensors. We used Two-Colour Sum-Frequen...
Article
We present a general formalism to model and calculate linear and nonlinear optical processes in composite systems , based on a graphical representation of light-matter interactions by loop diagrams associated with Feynman rules. Through this formalism, we recover the usual second-order response of a simple system by drawing four times fewer loop di...
Article
Full-text available
(Special issue: Recent Advances in Linear and Nonlinear Optics). Given the tunability of their optical properties over the UV–Visible–Near IR spectral range, ligand-capped quantum dots (QDs) are employed for the design of optical biosensors with low detection threshold. Thanks to non-linear optical spectroscopies, the absorption properties of QDs a...
Article
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(Special issue: Recent advances in linear and non-linear optics). To take advantage of the singular properties of matter, as well as to characterize it, we need to interact with it. The role of optical spectroscopies is to enable us to demonstrate the existence of physical objects by observing their response to light excitation. The ability of spec...
Article
The manufacturing of silica platforms functionalized by CdTe quantum dots (QDs) of 3.4 nm diameter through (3-aminopropy)triethoxysilane (APTES) aliphatic organosi-lanes is performed to preserve QDs excitonic properties after their transfer from col-loidal solutions to surfaces, at ambient air. In these conditions, the chemical stability and the st...
Article
In this paper, we report on the study of a novel type of substrate based on a highly crystalline ZnO film photo-irradiated using UV for enhancing the Raman signal. This effect is called photo-induced enhanced Raman spectroscopy (PIERS). This PIERS substrate is composed of a photo-irradiated thin ZnO film on which gold nanoparticles are deposited an...
Article
The Cover Feature illustrates the Förster resonant energy transfer from quantum dots to biomolecules tagged with a fluorophore. The aggregation of the quantum dots as a result of finely monitored functionalization of their surface involves the enhancement of this energy transfer. More information can be found in the Article by J. Hottechamps, L. Dr...
Article
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Front Cover paper: As luminescent quantum dots (QDs) are known to aggregate themselves through their chemical activation by carbodiimide chemistry and their functionalization with biotin molecules, we investigate both effects on the fluorescence properties of CdTe QDs and their impact on Förster Resonant Energy Transfer (FRET) occurring with fluore...
Article
The plasmonic amplification of non-linear vibrational sum frequency spectroscopy (SFG) at the surfaces of gold nanoparticles is systematically investigated by tuning the incident visible wavelength. The SFG spectra of dodecanethiol-coated gold nanoparticles chemically deposited on silicon are recorded for twenty visible wavelengths. The vibrational...
Article
Au-covered hollow urchin-like ZnO nanostructures were prepared with controlled size by combining nanosphere lithography (NSL), atomic layer deposition (ALD), electrodeposition, and electron beam (e-beam) evaporation. The optimal Au film thickness for sensing applications was determined by measuring the surface-enhanced Raman scattering (SERS) inten...
Preprint
Full-text available
The plasmonic amplification of non-linear vibrational sum frequency spectroscopy (SFG) at the surfaces of gold nanoparticles is systematically investigated by tuning the incident visible wavelength. The SFG spectra of dodecanethiol-coated gold nanoparticles chemically deposited on silicon are recorded for twenty visible wavelengths. The vibrational...
Preprint
Full-text available
(http://arxiv.org/abs/1906.03197) In quantum electrodynamics, optical processes are theoretically described by double-sided Feynman diagrams. This formalism is powerful in the case of molecules but proves inappropriate to account for light-matter interactions within complex hybrid systems constituted of organic and inorganic matter. The double-side...
Preprint
In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN -- from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-diazenyl}benzonit...
Article
Full-text available
Special issue: Plasmonics and its Applications. We report on the recent scientific research contribution of non-linear optics based on Sum-Frequency Generation (SFG) spectroscopy as a surface probe of the plasmonic properties of materials. In this review, we present a general introduction to the fundamentals of SFG spectroscopy, a well-established...
Data
New theoretical modeling of Two-Colour Sum-Frequency Generation spectroscopy of hybrid organic/inorganic complex interfaces
Article
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Journal : Communications Chemistry (Springer Nature) / Link: https://www.nature.com/articles/s42004-018-0079-y / Within semiconductor quantum dots (QDs), exciton recombination processes are noteworthy for depending on the nature of surface coordination and nanocrystal/ligand bonding. The influence of the molecular surroundings on QDs optoelectron...
Article
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This work describes an electrochemical study of 4-nitrobenzene diazonium (4-NBD) reduction onto glassy carbon (GC) electrode coupled to in situ sum-frequency generation (SFG) spectroscopy. After 4-NBD grafting at 0.3 V vs. saturated calomel electrode (SCE) onto GC, SFG allowed a clear signal assigned to the symmetrical vibration mode of the nitro (...
Article
Full-text available
We experimentally determine the effective nonlinear second-order susceptibility of gold over the visible spectral range. To reach that goal, we probe by vibrational two-color sum-frequency generation spectroscopy the methyl stretching region of a dodecanethiol self-assembled monolayer adsorbed on a gold film. The sum-frequency generation spectra sh...
Article
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Gold nanotriangles structured as honeycombs and fabricated by nanosphere lithography on a gold film are functionalised by thiophenol molecules in order to be used as plasmonic sensors in nonlinear optical sum frequency generation (SFG) spectroscopy. The monitoring and the characterisation of the surface optical properties are performed by UV–visibl...
Article
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- 2017 PCCP HOT Articles Themed Collection - Backcover of the PCCP issue. We investigate the effects of CdTe quantum dot (QD) concentration on their fluorescence in water. The emission spectra, acquired in right angle geometry, exhibit highly variable shapes. The measurements evidence a critical value of the concentration beyond which the intensit...
Article
Eight 1 cm 2 samples of self-organising zinc oxide (ZnO) nanopillar arrays with preferential vertical orientation were grown by pulsed laser deposition and then coated with 30 nm of Au using either thermal or electron-beam evaporation. Each sample had a different set of ZnO and Au growth conditions. The Au/ZnO nanoarrays were then tested for use in...
Article
In two previous papers (C. Mele, M. Catalano, A. Taurino, B. Bozzini. Electrochim. Acta 87 (2013) 918; B. Bozzini, A. Gianoncelli, C. Mele, M. Kiskinova. Electrochim. Acta 114 (2013) 889), we have: (i) fabricated high-capacitance materials consisting of nanoporous gold (NPG)-supported MnO2 nanowires (NW), by electrochemical etching of single-phase...
Article
Owing to their unique combination of wear resistance and toughness, cemented carbides are developing relevance in a systematically increasing number of applications, many of which involve notably corrosive environments. Petrochemical offshore extraction is one of the most appealing prospective fields of use of cemented carbides for critical general...
Article
Full-text available
We establish a new procedure to study the steady state adsorption of carbon monoxide (CO) at the surface of platinum under electrochemical control over a wide potential range in aqueous acidic solution. Using highly concentrated solutions of CO in perchloric acid medium enables the formation of a tightly packed and very stable CO monolayer at the s...
Article
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Gold nanoparticles (AuNPs) chemically grafted on substrates are widely used as sensors due to their plasmonic properties. The efficiency and robustness of such sensors strongly depend on the molecular sublayer structure, which influences the distribution of AuNPs, and therefore the plasmonic properties of the layer. Few spectroscopic tools are able...
Article
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Layers of thiophenol functionalized spherical gold nanoparticles grafted on Si(100) are probed by linear UV-vis, Fourier transform infrared and nonlinear infrared-visible vibrational sum/difference-frequency generation spectroscopies as a function of the nanoparticles surface coverage. Depending on the dipping time (5 min, 20 min, 1 h, and 24 h) in...
Article
Full-text available
The vibrational nonlinear activity of films of 2,4-dinitrophenyl phospholipid (DNP) at the solid interface is measured by sum-frequency generation spectroscopy (SFG). Hybrid bilayers are formed by a Langmuir-Schaefer approach in which the lipid layer is physisorbed on top of a self-assembled monolayer of dodecanethiol on Pt with the polar heads poi...
Article
In view of improved durability, the study of electrocatalyst supports for PEMFCs alternative to carbon is raising notable research interest. In this paper we investigated the oxidation of ethanol onWC-supported electrodeposited Pt, in pristine and aged conditions by: (i) electrochemical measurements, (ii) in situ spectroscopy (FTIR and sum-frequenc...
Article
Full-text available
In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN⁻ from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-diazenyl}benzonitri...
Article
Full-text available
We report the study of methanol electro-oxidation on ordered and defective Pt(110) surfaces using infrared- visible sum-frequency generation vibrational spectroscopy in the COads internal stretch spectral region (1700–2150 cm�1). Comparison of the spectra as a function of the structural quality of the electrodes and of the applied potential shows t...
Article
244th National Fall Meeting of the American-Chemical-Society (ACS), Philadelphia, PA, AUG 19-23, 2012
Article
Full-text available
Nonlinear optical Sum and Difference-Frequency spectroscopies are used to probe and model the surface of thiophenol-functionalised gold nanoparticles grafted on a Si(100) substrate through two different silanization procedures. By scanning the [980-1100 cm(-1)] infrared spectral range with the CLIO Free Electron Laser, ring deformation vibrations o...
Article
Full-text available
Infrared-visible sum-frequency generation (SFG) vibrational spectroscopy is applied to evidence the extramolecular Pt-C chemical bond and deduce an experimental value of its Raman activity at the CO/Pt(110) interface. This measurement, performed on a flat metal surface, without surface roughening, does not involve any enhancement of the electromagn...
Chapter
This chapter discusses different aspects of infrared-visible sum-frequency generation (SFG) spectroscopy. It emphasizes that this noninvasive optical probe could be considered as a versatile technique with various applications to biointerfaces. It underlines that SFG is more than a complementary probe to classical IR and Raman spectroscopies. It po...
Article
Full-text available
In this paper we report in situ sum-frequency generation (SFG) spectroscopy experiments, carried out during the electro-oxidation of ethanol on Pt-black supported on tungsten carbide (WC). Well-defined SFG resonances were measured in the 1320–1350 cm−1 spectral range with the VIS beam set at 523.5 nm. The assignment of SFG bands was carried out wit...
Article
Full-text available
We have investigated a metal-supported lipid film by using a sum frequency generation (SFG) spectrometer coupled to a free electron laser (FEL). DFT calculations on a molecular model have enabled to assign the vibrational signatures. The SFG vibrations detected in the backbone region, between 1375cm−1 and 1000cm−1, originate from the vibrational mo...
Article
In this paper we report an SFG/DFG investigation of the adsorption of CN− – used as a probe molecule to study the electrochemical double-layer structure – at a polycrystalline Au electrode in 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) room-temperature ionic liquid (RTIL). The adsorption of CN− yielded single SFG...
Article
Full-text available
Sum frequency generation (SFG) and difference frequency generation (DFG) are applied to study vibrational resonance of the thiophenol molecule adsorbed on two different gold samples. One sample is made of 17 nm gold nanoparticles (AuNPs) fixed on a silicon substrate that has been previously functionalized with a silane monolayer (aminopropyltrietho...
Article
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We have studied the apatite growth dynamics on tantalum oxide surfaces. This nucleation is obtained via an organosilane intermediate layer between the apatite and the substrate surface. Four organosilane layers (differing by their terminal functionality) were investigated. Their characterization with atomic force microscopy and other techniques suc...
Article
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A two-colour sum-frequency generation (2C-SFG) spectroscopy experiment was carried out on an assembly of Ag nanoparticles embedded in a Si3N4 matrix. The visible beam was fixed either at ωvis=441.6 nm in the surface plasmon resonance (SPR) of the Ag nanoparticles or at ωvis=632.8 nm, out of the SPR. The SFG signal was detected while the infrared be...
Article
Full-text available
Standard vibrational sum-frequency generation (SFG) spectroscopy is performed to probe the electrochemical cyanoacetylene/Au(1 1 1) interface, enlightening a 20 cm−1/V Stark shift of the free CN vibration mode of this cyanopolyynes-class molecule. SFG data suggest an orientation for the adsorbed molecules with the CN moiety pointing out in a direct...
Article
In this paper we report the first spectroelectrochemical in situ doubly resonant sum frequency generation (DR-SFG) spectroscopy experiment carried out with a free-electron laser tunable IR source and IR and VIS Optical Parametric Oscillators. We studied the potential-dependent adsorption and reaction of the quinoline dye 4-{2-[1-(2-cyanoethyl)-1,2,...
Article
Full-text available
Recently, thiocyanate groups were successfully used as precursors for thiolate assemblies. Indeed, they provide a useful alternative to thiol groups for self-assembly on metallic substrates. In order to check the adsorption properties and the quality of the thiocyanate-based self-assembled monolayers (SAMs), we use sum-frequency generation spectros...
Article
In a recent paper Ciszek et al. [J.W. Ciszek, M.P. Stewart, J.M. Tour, J. Am. Chem. Soc. 126 (2004) 13172] showed that organic thiocyanates may be an interesting alternative to the use of thiols for thiolate assemblies. We use scanning tunnelling microscopy (STM), infrared reflection absorption and sum-frequency generation spectroscopies (IRRAS and...
Article
Monolayers of protoporphyrin-IX molecules are prepared on a Pt(111) surface by a self-assembly process in order to manufacture organic devices with controlled electronic properties. Scanning tunnelling microscopy (STM) and two-colour sum-frequency generation (2C-SFG) are performed ex situ in ambient air, in order to characterize their molecular con...
Article
Full-text available
Atomic force microscopy (AFM) is used to describe the formation process of polymer/DNA complexes. Two main objectives of this research are presented. The first one is to apply AFM as an effective tool to analyse DNA molecules and different polycation/DNA complexes in order to evaluate their degree of condensation (size and shape). The other one is...
Article
We use infrared-visible sum-frequency generation (SFG) spectroscopy in order to investigate the adsorption properties on Pt(111) of molecules having CH3–C6H4–(O–CH2–CH2)n–O–(CH2)m–SH as general chemical formula. We synthesized three molecules defined by the values m = 5 n = 4, m = 11 n = 4, m = 11 n = 8 and characterized them by Nuclear Magnetic Re...
Article
Challenging Characterisation: Precise determination of the conformation and electronic properties of haemoporphyrin–metal interfaces are important for device characterisation. The authors show that metalloporphyrins lie more planar on the substrate than the metal-free porphyrins, which are less tilted with respect to the surface normal direction (s...
Article
Overlayers of a fatty acid (palmitic and lauric acid) formed at the interface between a solution of this molecule in phenyloctane and the basal plane of graphite are studied by in situ scanning tunnelling microscopy. The layers organize into lamellae, which are formed by a close packing arrangement of molecules parallel to the graphite surface. Che...
Article
The influence of chemical modification of scanning tunnelling microscopy tips on image contrast is studied. This technique is applied to the identification of an ester functional group, hardly visible otherwise. Self-assembled overlayers of wax esters [CH3-(CH2)14-CO-O-(CH2)15-CH3], adsorbed at the interface between highly oriented pyrolitic graphi...
Article
Full-text available
For the first time, the sum-frequency generation (SFG) spectra of surface species have been measured in porous silicon (PS) layers. The range of the vibrations 2000–2300 cm–1 for the native species Si–Hx has been explored. Furthermore for the studied mesoporous materials, it has been found that, as opposed to the infrared absorption, the SFG signal...
Article
Full-text available
We use sum-frequency generation spectroscopy (SFG) in the infrared 2800–3000 cm−1 spectral range and UV–vis spectroscopy (transmission) in the 450–650 nm spectral range in order to characterize vibrational and electronic properties of various interfaces composed of organic monolayers adsorbed on gold nanoparticles (AuNPs) with 19 nm average diamete...