Sum-frequency generation characterization of the molecular recognition of avidin by biocytin films adsorbed on metallic substrates

Poster (2003, June)

E lectron–phonon couplings at C60 interfaces: a case study by two- color, infrared–visible sum–frequency generation spectroscopy

in Journal of Electron Spectroscopy & Related Phenomena (2003), 129

We demonstrate the ability of doubly resonant sum–frequency generation (DR-SFG) to investigate electron–phonon couplings at C60 –metal interfaces. Due to its coupling to electronic transitions, the ... [more ▼]

We demonstrate the ability of doubly resonant sum–frequency generation (DR-SFG) to investigate electron–phonon couplings at C60 –metal interfaces. Due to its coupling to electronic transitions, the totally symmetric Ag(2) vibration of C60 exhibits a huge enhancement of its nonlinear response for sum–frequency energies above the molecular electronic gap. We attribute this resonance to the coupling of the pentagonal pinch mode with the tiu lowest unoccupied molecular orbital (LUMO) of C60. [less ▲]

Probing a molecular electronic transition by two-colour sum-frequency generation spectroscopy

in Applied Surface Science (2003), 212–213

We demonstrate that a new emerging technique, two-colour sum-frequency generation (SFG) spectroscopy, can be used to probe the molecular electronic properties of self-assembled monolayers (SAMs). In the ... [more ▼]

We demonstrate that a new emerging technique, two-colour sum-frequency generation (SFG) spectroscopy, can be used to probe the molecular electronic properties of self-assembled monolayers (SAMs). In the CH spectral range (2800–3200 cm-1), we show that the sum-frequency generation signal of a porphyrin alkanethiol derivative adsorbed on Pt(1 1 1) reaches a maximum intensity at ~435 nm SFG wavelength. This wavelength corresponds to the porphyrin moiety specific p–p*$ molecular electronic transition which is called the Soret or B band. This resonant behaviour is not observed for 1-dodecanethiol SAMs, which are devoid of molecular electronic transition in the investigated visible spectral range. [less ▲]

Two-color sum-frequency generation spectroscopy: a powerful tool for the study of self-assembled monolayers

Poster (2002, June)

IR-visible sum-frequency vibrational spectroscopy of Biphenyl-3 methylene thiol monolayer on gold and silver: effect of the visible wavelength on the SFG spectrum

in Surface Science (2002), 502-503

We measured IR-visible sum-frequency generation spectra of CH3-(C6H4)2-(CH2)3-S-H (Biphenyl-3) self-assembled monolayers on a silver and a gold substrate. For the latter substrate, we observed different ... [more ▼]

We measured IR-visible sum-frequency generation spectra of CH3-(C6H4)2-(CH2)3-S-H (Biphenyl-3) self-assembled monolayers on a silver and a gold substrate. For the latter substrate, we observed different interference patterns between the resonant signal of the CH vibration and the non-resonant contribution of the substrate as a function of the visible beam wavelength. The non-linear response of the gold substrate is enhanced around 480 nm corresponding to the s-d interband transition. Such effect is not observed for the silver substrate the interband transition of which is located out of the investigated visible spectral range of 450-700 nm. [less ▲]

Influence of the metal electronic properties on the sum-frequency generation spectra of dodecanethiol self-assembled monolayers on Pt (111), Ag (111) and Au (111) single crystals

in Applied Physics B : Lasers & Optics (2002), 74

Infrared-visible sum-frequency generation (SFG) spectroscopy is performed at different visible wavelengths between 450 and 650 nm in order to investigate the interaction between metallic substrates (Pt ... [more ▼]

Infrared-visible sum-frequency generation (SFG) spectroscopy is performed at different visible wavelengths between 450 and 650 nm in order to investigate the interaction between metallic substrates (Pt, Ag and Au) and 1-dodecanethiol self-assembled monolayers. We show that such measurements provide a means to study the electronic properties of metals as well as the interference phenomena between the SFG signals from the adsorbate and the substrate. The common features of the three interfaces are the vibration modes of the terminal methyl groups. However, these resonances appear as peaks for Pt (111) and as dips in the case of Ag (111). Their shape is not modified when the visible wavelength is tuned between 450 and 650 nm. Moreover, the metal sum-frequency generation contribution is slightly modified in that spectral range. For Au (111) samples, the sum-frequency generation spectrum drastically evolves with the visible wavelength: the peak resonant sum-frequency generation signal at 450 nm becomes rather dip-shaped at 650 nm. The non-linear response of gold is also enhanced when the wavelength associated with the sum-frequency process is close to 480 nm. These results are interpreted on the basis of the metal electronic properties that are responsible for the non-resonant contribution to the SFG signal. [less ▲]

Sum-frequency generation characterisation of the water/polyethylene glycol interface

Poster (2001, June)

Study of the water/poly(ethylene glycol) interface by IR-visible sum-frequency generation spectroscopy

in Chemical Physics Letters (2001), 333

We used infrared-visible sum-frequency generation spectroscopy to investigate the vibrational properties of the water/poly(ethylene glycol) interface in the 2800-3800 cm-1 spectral range. The vibrational ... [more ▼]

We used infrared-visible sum-frequency generation spectroscopy to investigate the vibrational properties of the water/poly(ethylene glycol) interface in the 2800-3800 cm-1 spectral range. The vibrational fingerprint of the interface differs significantly from the one associated with the aire/poly(ethylene glycol) interface. It is shown that the poly(ethylene glycol) molecular arrangement, originally relatively well-ordered, becomes disorganised in the presence of water. Moreover, a new OH band is identified demonstrating the strong interaction of water with the polymer. [less ▲]

Sum-frequency generation characterisation of methanol, pentadecanoïc acid and water interfaces

Poster (2000, May)

Development of an all-solid-state pulsed Nd:YAG laser for pumping picosecond OPO systems

in Proceedings (1999)

High performance mode-locking of a pulsed Nd:YAG laser was achieved at 1.064 µm by using a frequency doubling nonlinear mirror (FDNLM) based on a BBO crystal for second harmonic generation and on a ... [more ▼]

High performance mode-locking of a pulsed Nd:YAG laser was achieved at 1.064 µm by using a frequency doubling nonlinear mirror (FDNLM) based on a BBO crystal for second harmonic generation and on a dichroïc mirror. A GaAs platelet was inserted into the laser cavity for providing a passive negative feedback. Pulses shorter than 15 ps were generated. The FDNLM has the following merits: photochemical stability, short response time, simplicity and applicability to a wide spectral range. The optical oscillator is the first element of a two-color laser system including two synchronously pumped optical parametric oscillators (OPO) built around a BBO and a LiNbO3 crystal, and tunable from 410 to 2600 nm and from 2.5 to 3.6 µm, respectively. [less ▲]