Self-Assembled Film Organization in Fast Microcontact Printing Investigated by Sum Frequency Generation Spectroscopy

in Journal of Physical Chemistry C: Nanomaterials, Interfaces, and Hard Matter (2009), 113

The ability of microcontact printing to build highly ordered alkanethiol self-assembled monolayers (SAMs) on Pt substrates within a short time is studied by sum frequency generation (SFG) spectroscopy and ... [more ▼]

The ability of microcontact printing to build highly ordered alkanethiol self-assembled monolayers (SAMs) on Pt substrates within a short time is studied by sum frequency generation (SFG) spectroscopy and contact angle measurements. The deposition of ordered hexadecanethiol and dodecanethiol monolayers onto platinum substrates is achieved in less than 1 s. The film order and the alkane chain orientation are deduced from the SFG fingerprint acquired under different sets of laser polarization. Comparisons between the SAMs prepared by printing or by immersion demonstrate that both methods lead to the same high quality organization. Patterning effects within printed films are also investigated with respect to the layer conformation. Finally, wetting properties of printed layers are correlated with the printing duration, corroborating the spectroscopic results. [less ▲]

Adsorption properties of decyl thiocyanate and decanethiol on platinum substrates studied by sum-frequency generation spectroscopy

in Surface Science (2007), 601

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 ... [more ▼]

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 spectroscopy (SFG) and apply it to characterize the ad-layers of two similar molecules: decanethiol (DT) and decyl thiocyanate (DTCN) adsorbed on platinum surfaces. By comparing the SFG signals of the methyl and methylene vibration modes, we show that DTCN SAMs are less ordered than DT ones. These effects are related to the SAMs quality which depends on the molecular packing as highlighted by scanning tunnelling microscopy and X-ray photoelectron spectroscopy. [less ▲]

Total internal reflection sum-frequency generation spectroscopy and dense gold nanoparticles monolayer: a route for probing adsorbed molecules

in Nanotechnology (2007), 18

We show that sum-frequency generation spectroscopy performed in the total internal reflection configuration (TIR–SFG) combined with a dense gold nanoparticles monolayer allows us to study, with an ... [more ▼]

We show that sum-frequency generation spectroscopy performed in the total internal reflection configuration (TIR–SFG) combined with a dense gold nanoparticles monolayer allows us to study, with an excellent signal to noise ratio and high signal to background ratio, the conformation of adsorbed molecules. Dodecanethiol (DDT) was used as probe molecules in order to assess the potentialities of the approach. An enhancement of more than one order of magnitude of the SFG signals arising from the adsorbed species is observed with the TIR geometry compared to the external reflection one while the SFG non-resonant contribution remains the same for both configurations. Although further work is required to fully understand the origin of the SFG process on nanoparticles, our work opens new possibilities for studying nanostructures. [less ▲]

On the Protoporphyrin Monolayers Conformation

in Chemphyschem : A European Journal of Chemical Physics and Physical Chemistry (2006), 7

Comparative study of decyl thiocyanate and decanethiol self-assembled monolayers on gold substrates

Poster (2005, September)

Sum-frequency generation from surface species in porous silicon

in Phys. Stat. Sol. (a) (2005), 202(8), 1487-1491

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 ... [more ▼]

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 increases with porosity. Finally, the angular dependence and the enhancement of the SFG signal were measured in a one-dimensional PS photonic crystal structure with a defect producing an energy level in the photonic band gap. [less ▲]

Two-color-sum-frequency generation characterization of a protein monolayer adsorbed on a metallic substrate

Poster (2004, June)

Probing Ligand–Protein Recognition with Sum-Frequency Generation Spectroscopy: The Avidin–Biocytin Case

in Chemphyschem : A European Journal of Chemical Physics and Physical Chemistry (2004), 5

Infrared/visible sum-frequency generation (SFG) spectroscopy is used to study the recognition of a protein (avidin) by a derived vitamin (biocytin) adsorbed on a calcium fluoride substrate. The ... [more ▼]

Infrared/visible sum-frequency generation (SFG) spectroscopy is used to study the recognition of a protein (avidin) by a derived vitamin (biocytin) adsorbed on a calcium fluoride substrate. The specificity of the process is tested by replacing avidin with bovine serum albumin or presaturated avidin. The SFG spectroscopy shows drastic modifications in the CH and NH spectral ranges only upon exposure of the biocytin film to avidin. The comparison of the SFG data with Fourier transform infrared reflection absorption spectra (FT-IRRAS) in the same spectral ranges illustrates the advantages of nonlinear spectroscopy for studying and detecting recognition between biomolecules. [less ▲]

Study by sum-frequency generation spectroscopy of a model biosensor : the biocytin-avidin complex

Poster (2003, May)