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Laser-Driven Bubble Printing of Plasmonic Nanoparticle Assemblies onto Nonplasmonic Substrates


The use of optically controlled vapor bubbles for controlled synthesis and deposition at interfaces is a promising emerging technique, which is intrinsically limited by the ability of the system to provide enough heat for bubble formation that is typically addressed using a plasmonic substrate. Herein, a simple and fast method for laser-controlled printing of plasmonic nanoparticles onto nonplasmonic substrates is shown. The laser fluence needed to print the nanoparticle was lowest for nanoparticles in resonance with the laser wavelength, but the technique is also effective off-resonance. Hierarchical assemblies were obtained, where melting was observed up to a micron from the focal point of the laser beam. The assemblies show plasmonic properties in the unmelted region, as shown by surface-enhanced Raman scattering spectroscopy measurements. This work will lead to future studies on controlling the hierarchical structure of nanoparticle assemblies formed at the bubble interface toward applications in sensing and devices.

Thanks to Eric Hill and his nice microscope for printing plasmonic patterns.

Double-lattice packing of pentagonal gold bipyramids in supercrystals with triclinic symmetry


Pentagonal packing is a long-standing issue and a rich mathematical topic, brought to the fore by recent progress in nanoparticle design. Gold pentagonal bipyramids combine five-fold symmetry and anisotropy and their section varies along the length. In this work, we obtain colloidal supercrystals of pentagonal gold bipyramids in a compact arrangement that generalizes the optimal packing of regular pentagons in the plane. Multimodal investigations reveal a two-particle unit cell with triclinic symmetry, a lower symmetry than that of the building blocks. Monte Carlo computer simulations show that this lattice achieves the densest possible packing. Going beyond pentagons, further simulations show an odd-even effect of the number of sides on the packing: odd-sided bipyramids are non-centrosymmetric and require the double-lattice arrangement to recover inversion symmetry. The supercrystals display a facet-dependent optical response that is promising for sensing, metamaterials applications and for fundamental studies of self-assembly processes.


Welcome Jianan!



I obtained my Bachelor of Engineering in Nano Materials and Technology from Soochow University in China. During my undergraduate study, I worked on several projects related to nanoscaled functional materials for energy conversion and storage under the supervision of Prof. Yanguang Li.


I am now the M2 student from Erasmus Mundus Joint Master program: SERP+. Currently, I am working on my thesis project about self-assembly of colloidal liquid crystal in levitation under the supervision of Dr. Cyrille Hamon and Dr. Erwan Paineau.

Happy 2022!

credit photo MATRIX team: Fréedericksz transition in a biaxe smectic phase

Unveiling the Coupling of Single Metallic Nanoparticles to Whispering-Gallery Microcavities


Abstract Image Nice work published in collaboration with the STEM group @ LPS


Whispering-gallery mode resonators host multiple trapped narrow-band circulating optical resonances that find applications in quantum electrodynamics, optomechanics, and sensing. However, the spherical symmetry and low field leakage of dielectric microspheres make it difficult to probe their high-quality optical modes using far-field radiation. Even so, local field enhancement from metallic nanoparticles (MNPs) coupled to the resonators can interface the optical far field and the bounded cavity modes. In this work, we study the interaction between whispering-gallery modes and MNP surface plasmons with nanometric spatial resolution by using electron-beam spectroscopy with a scanning transmission electron microscope. We show that gallery modes are induced over a selective spectral range of the nanoparticle plasmons, and additionally, their polarization can be controlled by the induced dipole moment of the MNP. Our study demonstrates a viable mechanism to effectively excite high-quality-factor whispering-gallery modes and holds potential for applications in optical sensing and light manipulation.

Thanks to the STEM group @ LPS and especially to Yves Auad whom carried out the experiments.

Gold-clay nanocomposite colloids with liquid-crystalline and plasmonic properties


Imparting liquid-crystal (LC) materials with the plasmonic properties of metal nanoparticles is actively pursued for applications. We achieved this goal by synthetizing gold nanoparticles onto clay nanosheets, leading to nematic nanocomposite suspensions. Optical observations and structural analysis show the growth of the gold nanoparticles without altering the LC properties of the nanosheets. These colloids display plasmonic structural colours and they can be aligned by an electric field, which is relevant for fundamental and materials chemistry of colloidal LC.


Doping Liquid Crystals of Colloidal Inorganic Nanotubes by Additive-Free Metal Nanoparticles


Doping liquid-crystal phases with nanoparticles is a fast-growing field with potential breakthroughs due to the combination of the properties brought by the two components. One of the main challenges remains the long-term stability of the hybrid system, requiring complex functionalization of the nanoparticles at the expense of their self-assembly properties. Here we demonstrate the successful synthesis of additive-free noble-metal nanoparticles at the surface of charged inorganic nanotubes. Transmission electron microscopy and UV-visible spectroscopy confirm the stabilization of metallic nanoparticles on nanotubes. Meanwhile, the spontaneous formation of liquid-crystals phases induced by the nanotubes is observed, even after surface modification with metallic nanoparticles. Small-angle X-ray scattering experiments reveal that the average interparticle distance in the resulting hybrids can be easily modulated by controlling electrostatic interactions. As a proof-of-concept, we demonstrate the effectiveness of our method for the preparation of homogeneous transparent hybrid films with a high degree of alignment.

Symmetry breaking in seed-mediated silver nanorod growth induced by dimethyl sulfoxide


Engineering symmetry breaking in seed-mediated growth is a fundamental challenge to produce colloidal nanocrystals with controlled morphologies and properties. In this work, we show a simple, aqueous approach to breaking the inversion symmetry of silver nanorods by restricting growth to one end of the pentatwinned gold bipyramid seed. Controlled addition of dimethyl sulfoxide (DMSO) allows us to tune both the symmetry and the length and width of the objects. Simulations and experiments demonstrate the adsorption of DMSO, which displaces interfacial water, reduces binding of surfactant and chloride ions at the gold surface, and slows down the deposition kinetics of silver. Besides showing the potential of DMSO for controlling the synthesis of complex nanostructures, this work opens new perspectives for the study of the physical properties of non-centrosymmetric nanoparticles, e.g. by controlling their plasmon modes and their second-harmonic generation efficiency.

Structure and Formation Kinetics of Millimeter-Size Single Domain Supercrystals



Organizing nanoparticles (NPs) into periodic structures is a central goal in materials science. Despite progress in the last decades, it is still challenging to produce macroscopic assemblies reliably. In this work, we report the analysis of the pervaporation-induced organization of gold octahedra into supercrystals within microfluidic channels using a combination of X-ray scattering techniques and FIB-SEM tomography. The results reveal the formation of a single-domain supercrystal with a monoclinic C2/m symmetry and long-range order extending over the dimensions of the microfluidic channel, covering at least 1.7x0.3 mm2. Time-resolved small angle X-ray scattering analysis showed that the formation of the superlattice involves an accumulation of the NPs within the channel before the nucleation and growth of the supercrystal. The orientation of the crystal remains unchanged during its formation, suggesting a growth mechanism directed by the channel interface. Together, these results show the potential application of the pervaporation strategy to providing spatially determined control over NP crystallization, which can be used for the rational fabrication of nanomaterial architectures.

Sharp Spectral Variations of the Ultrafast Transient Light Extinction by Bimetallic Nanoparticles in




Welcome Samantha!



Samantha Roque earned her Bachelor of Science in Chemistry (2017) and in Materials Science Engineering (2018) from Ateneo de Manila University in the Philippines. She worked on printable carbon composites and biosilica inks for perovskite solar cells under Erwin P. Enriquez, Ph.D. 
She is now doing her master's degree under the Erasmus Mundus Joint Master Degree SERP+. She is at present doing her internship on Anisotropic plasmonic-semiconductor nanocomposites for photocatalytic applications which is a joint project between the “Institut de Chimie Physique” and the “Laboratoire de Physique des Solides” supervised by Cyrille Hamon Ph.D. and ‪Mohamed Nawfal Ghazzal, Ph.D. 

Two-step assembly kinetics of gold nanoparticles



Abstract: We study the assembly kinetics of surfactant-stabilized gold nanoparticles in the presence of sulfate ions. The reaction proceeds in two steps: very rapid (a few minutes) formation of amorphous aggregates, followed by slow reordering (over several hours). The latter process is the only one detectable via absorbance spectroscopy and results in the formation of intimate contacts between the objects, with interparticle distances below the thickness of a surfactant bilayer. The rate-limiting step of the reaction could be related to surfactant expulsion from the initial aggregates, which allows the particles to come in close contact and form chains. There are marked differences in reaction yield and rate constant between spheres, rods and bipyramids, highlighting the role of surface curvature in contact formation. Once formed, the assemblies are very sturdy and stable under centrifugation and dialysis. The contact interaction is strong and highly directional, as shown by liquid-cell transmission electron microscopy.




Happy new year!


Two papers accepted on bimetallic NPs synthesis



Determining the morphology and concentration of
core-shell Au/Ag nanoparticles


Growth kinetics of core-shell Au/Ag nanoparticles


Welcome Wajdi!


Wajdi is a new postdoctoral researcher in the team MATRIX. His interest focuses on self-assembling plasmonic nanoparticles in confinement. The nanostructuration will be resolved at the single supercrystal level using an innovative Small Angle X-ray Scattering (SAXS) setup developed on a synchrotron beamline (SWING, @SOLEIL).

Real-Time In Situ Observations Reveal a Double Role for Ascorbic Acid in the Anisotropic Growth of S


Our article have been published in J. Phys. Chem. Lett. Those results have been obtained during the M2 internship of Kinanti Aliyah. It is a collaborative work with the SOLEIL Synchrotron and MPQ lab (Université de Paris). 

DOI: acs.jpclett.0c00121

Abstract: Rational nanoparticle design is one of the main goals of materials science, but it can only be achieved via a thorough understanding of the growth process and of the respective roles of the molecular species involved. We demonstrate that a combination of complementary techniques can yield novel information with respect to their individual contributions. We monitored the growth of long aspect ratio silver rods from gold pentatwinned seeds by three in situ techniques (small-angle x-ray scattering, optical absorbance spectroscopy and liquid-cell transmission electron microscopy). Exploiting the difference in reaction speed between the bulk synthesis and the nanoparticle formation in the TEM cell, we show that the anisotropic growth is thermodynamically controlled (rather than kinetically) and that ascorbic acid, widely used for its mild reductive properties plays a capping role, by stabilizing the {100} facets of the silver cubic lattice, in synergy with the halide ions. This approach can be easily applied to a wide variety of synthesis strategies.

Plasmonic NPs patchwork

Selection of TEM images of Au or Au@Ag NPs with various morphology. The colors distinct series of nanocrystal: gold bipyramids of different size (purple), Au@Ag nanorods of varying shell thickness (red), Au@Ag bipyramids of varying shell length (green).

Happy new year!

Master intership opportunities


We are looking for motivated candidates for master 2 internships.

One topic concern the continuation of the intership of Kinanti Aliyah (M2 SERP Chem), about following in real time Au@Ag nanoparticles growth. You can find information about the techniques by reading this preprint:

The other topic is about resolving the 3D structure of plasmonic supercrystals and study the resulting collective optical properties by Surface Enhanced Raman Scattering (SERS) spectroscopy.

If one of those subjects interest you, please contact us.

Multiscale deposition of noble metal nanoparticles



Building nanoscale devices is a crucial step towards the success of nanotechnologies. The assembly of colloidal nanoparticles is a technology in development that may outperform standard lithography techniques in the future. Three-dimensional materials with possibly sub-nanometric inter-distances would be easily manufactured this way. Many groups work towards this goal, but some challenges still need to be addressed, such as the propagation of the order to large length scales. In this work, we demonstrate the organization of anisotropic nanoparticles with controlled local order, which spans the whole sample area.

Two complementary techniques (SAXS and TEM) are used to characterize assemblies of Au/Ag heterostructures. In SAXS, the spot size is macroscopic, about 500×200 µm², while in TEM the characterization is made locally, over hundreds of nanometers. The nanoparticles are pointing toward us in the TEM image, organized here in a square in-plane arrangement that can be modulated according to their cross-section.

In this work we used hybrid Au/Ag particles due to their fascinating optical properties. These nanoobjects consist of gold nanorods encased in silver shells with a thickness that can be controlled from a few atomic layers to tens of nanometers. The section of the nanoparticle, initially octagonal, becomes square for a sufficiently thick silver shell. We aimed at studying the impact of the morphological changes of the building blocks on their assembly into superlattices. Usually, nanoparticle assemblies are characterized locally by transmission electronic microscopy (TEM) and give only a limited picture of the assembly on a larger scale. In addition, we used Small Angle X-Ray Scattering (SAXS) to scan the sample area with a probe having much larger dimensions than the nanoparticles. This structural study shows that the nanorods are oriented in the same direction over the whole sample area, thanks to a well-chosen surface chemistry. Furthermore, hexagonal or square phases were formed depending on the octagonal or square cross section of the nanoparticles respectively, demonstrating a control of the multi-scale organization in the system.


Reference: C. Hamon, C. Goldmann and D. Constantin, Nanoscale, 2018, DOI: 10.1039/C8NR06376A.

1 PhD position (ANR)


Spontaneous organization of mineral nanoparticles

The recent expansion of the field of “chimie douce” (soft chemistry) has led to a wide variety of anisotropic nanoparticles of all kinds of nature and shape (nanotubes, nanosheets, nanorods, etc.). These nanoparticles can often be dispersed in water or in organic solvents as colloidal suspensions. Quite often, these suspensions spontaneously organize in liquid-crystalline phases of different types (nematic, lamellar, columnar …).1,2 Moreover, these suspensions can also be destabilized to produce aggregates with well-defined structures.3-5 These two kinds of phenomena are very useful to manipulate and organize nanoparticles in order to obtain original physical properties. For example, by applying electric or magnetic fields, we can align anisotropic nanoparticles and even sometimes order them on a lattice.

At this moment, we have suspensions of various nanoparticles (clay and H3Sb3P2O14 nanosheets, imogolite nanotubes, CdSe and CeF3 nanoplatelets …) whose phase diagrams and original physical properties still need to be fully explored. This thesis will take place at the LPS which is a joint research unit of CNRS and University Paris-Saclay, specialized in condensed-matter physics. This PhD topic belongs to a more general project, funded by ANR, which aims at using the properties of these nanoparticles to elaborate sensors to monitor water quality.

[1] E.Paineau et al, Liquid Crystals Reviews, 1, 110 (2013).

[2] E.Paineau et al, Nature Communications, 7, 10271 (2016).

[3] B.Abécassis et al, Nanoletters, 14, 710 (2014).

[4] S.Jana et al, Angewandte Chemie, 55, 9371 (2016).

[5] S.Jana et al, Science Advances, 3, e1701483 (2017). 


Techniques: X-ray scattering in-house and at large synchrotron radiation facilities (SOLEIL, ESRF), optical and electron microscopies, UV-vis spectroscopies, classical laboratories techniques of sample elaboration.


Required profile: Good level physicist or physical chemist. This thesis in experimental physics / physical chemistry will nevertheless involve a strong collaboration with chemists and theorists.


Funding: Project funded by ANR   


Thesis advisors: Patrick Davidson, Jean-Christophe Gabriel



2 PhDs positions opening


The 2018 doctoral award campaign of the Ministry of Higher Education, Research and Innovation (MESRI in french) is open for ED 2MIB.

It takes place in 4 phases:

1/ Student applications on the ED's website before April 27th
2/ Selection of only one candidate for each project before April 30th
3/ Audition of the candidates by the CIM Pole Jury of the ED (May 18th)
4/ Validation and publication of the results by the ED (June 15th).
The candidate will pass an oral examination in front of a Jury (May 18th).
If you are interested, please contact us in advance so we can prepare well the audition which is determinant in the selection process.

click here for details and application:

subject 1: Nanocomposites plasmoniques: amélioration des propriétés d'interfaces

subject 2: Matériaux structurés innovants: étude structurale par diffusion des rayons X

The surprising self-organization of nanotubes in a very dilute columnar liquid-crystal phase


Liquid crystals have found wide applications in many fields ranging from detergents to information displays. They are an important class of “soft matter” and they are increasingly being used in the “bottom-up” self-assembly approach of the nano-structuration of materials. Moreover, liquid-crystalline organizations are frequently observed by biologists. A research team of the LPS, in collaboration with researchers from CEA-Saclay (NIMBE-LIONS), has recently discovered that one of the four major lyotropic liquid-crystal phases, the columnar one, is actually much more stable (by a factor 100 in concentration!) than considered up to now.

Nanotubes (or nanorods) in colloidal suspensions form a columnar liquid-crystal when they spontaneously organize parallel to each other, on a two-dimensional lattice perpendicular to their axes, like a bunch of pencils (Figure a). This organization was so far only expected in concentrated suspensions where the nanorods are close to contact. Here, researchers at LPS and LIONS have shown that very dilute suspensions of clay imogolite nanotubes form a columnar liquid-crystal. Imogolites are aluminosilicates (or aluminogermanates) that have raised increasing interest in the last decade. In contrast with carbon nanotubes, they are easily obtained by sol-gel processes at low temperature. Moreover, the presence of hydroxyl groups on their surface makes these nanotubes quite hydrophilic, which allows producing aqueous suspensions.

Figure: a) Schematic representation of the organisation of the nanotubes in the columnar hexagonal liquid-crystalline phase (a et b are the unit vectors of the hexagonal lattice) ; b) Small angle X-ray scattering pattern of the columnar phase aligned in an electric field; c) Structure factor showing the reflections (indicated by the red lines) of the hexagonal lattice.


Texture observations of very dilute suspensions (volume fraction ~ 0.3%) by polarized-light microscopy revealed the existence of an unexpected liquid-crystalline phase. Small-angle X-ray scattering measurements, performed at the SOLEIL synchrotron (Swing beamline) showed that this new phase is a columnar hexagonal liquid crystal (Figure b, c).

Despite the high dilution, the nanotubes are perfectly organized on a hexagonal lattice with a spacing (~ 80 nm) fifteen times larger than the nanotube diameter. This dilute liquid-crystal is so fluid that the nanotubes are easily aligned in an electric field, which is a prerequisite for future applications. This work has important implications for the statistical physics of colloidal suspensions of charged rod-like particles, like biopolymers, and their fundamental understanding. It also opens new perspectives, for instance, in the field of nanocomposite materials where the organization of anisotropic particles is required to improve physical properties.



Paineau E., Krapf, M.E.M., Amara M.S., Matskova, N.V., Dozov, I., Rouzière S., Thill, A., Launois, P. et Davidson, P.. A liquid-crystalline hexagonal columnar phase in highly-dilute suspensions of imogolite nanotubes. Nat. Commun., 7, 10271 (2016)


Erwan Paineau (

Patrick Davidson (

Laboratoire de Physique des Solides, CNRS, Univ. Paris Sud, Université Paris Saclay, 91405 Orsay cedex, France

Review article free to download


We are pleased to share our review article "Colloidal Design of Plasmonic Sensors Based on Surface Enhanced Raman Scattering", published in Journal of Colloid and Interface Science, is now available online and free to download until December 26, 2017. This is a joint work with Luis Liz Marzan (CIC Biomagune, Spain). You can access the article by cliking on the following link:



Abstract: This feature article focuses on the use of colloid chemistry to engineer metallic nanostructures toward application in surface enhanced Raman scattering (SERS) sensing, in particular for ‘real-life’ applications, where the analyte may be present in complex mixtures. We present a broad summary of the field, including recent advances that have been developed during the past 10 years. Real-life applications require a rational design and we aimed at identifying the key elements involved in it. The discussion is centered around colloidal plasmonic nanoparticles and therefore we start from the library of morphologies that have been reported in the literature. To complete the picture, colloidal self-assembly, surface chemistry and the combination with materials science techniques are highlighted. Considering the progress in the field, SERS may ultimately realize its full potential as an ultrasensitive tool for routine analytical applications.