Publications de Hilton Barbosa De Aguiar

On the stability and necessary electrophoretic mobility of bare oil nanodroplets in water

Sylvie Roke, Hilton Barbosa De Aguiar, Saranya Pullanchery Sankara Narayanan, Halil Ibrahim Okur, Sergey Kulik

Hydrophobic oil droplets, particles, and air bubbles can be dispersed in water as kinetically stabilized dispersions. It has been established since the 19th century that such objects harbor a negative electrostatic potential roughly twice larger than the t ...

AMER INST PHYSICS2020

The Presence of Ultralow Densities of Nanocrystallites in Amorphous Poly(lactic acid) Microspheres

Sylvie Roke, Hilton Barbosa De Aguiar

Ultralow densities of crystalline nanospheres have been detected in amorphous polymer microspheres by utilizing the unique sensitivity of second-order nonlinear optical techniques to anisotropy. Vibrational sum frequency scattering (SFS) and X-ray diffract ...

Amer Chemical Soc2013

Comparison of scattering and reflection SFG: a question of phase-matching

Sylvie Roke, Kailash Chandra Jena, Hilton Barbosa De Aguiar, Rüdiger Scheu

We present a comparison between sum frequency scattering (SFS) and reflection mode sum frequency generation (R-SFG). We have used scattering theory to describe both scattering experiments as well as reflection mode experiments. The interfacial vibrational ...

2012

Erratum: Probing nanoscopic droplet interfaces in aqueous solution with vibrational sum-frequency scattering: A study of the effects of path length, droplet density and pulse energy (Chemical Physics Letters (2011) 512 (7680))

Sylvie Roke, Hilton Barbosa De Aguiar

Elsevier2012

Vibrational Sum-Frequency Scattering Studies of Oil-in-Water Emulsions

Hilton Barbosa De Aguiar

Oil-in-water emulsions consist of oil droplets dispersed in an aqueous phase. Interfacial properties of the droplets determine the stability of emulsions. Even though this statement is widely accepted, a molecular level picture of the droplet interface is ...

EPFL2011

Surface Structure of Sodium Dodecyl Sulfate Surfactant and Oil at the Oil-in-Water Droplet Liquid/Liquid Interface: A Manifestation of a Nonequilibrium Surface State

Sylvie Roke, Hilton Barbosa De Aguiar

We present sum frequency scattering spectra on kinetically stabilized emulsions consisting of nanoscopic oil droplets in water, stabilized with sodium dodecyl sulfate (SDS). We have measured the interfacial structure of the alkyl chains of the surfactant m ...

2011

Probing nanoscopic droplet interfaces in aqueous solution with vibrational sum-frequency scattering: A study of the effects of path length, droplet density and pulse energy

Sylvie Roke, Hilton Barbosa De Aguiar

We present a description of sum frequency scattering experiments to probe the interfacial vibrational spectrum of nanoscopic oil droplets dispersed in water. SF scattering measurements as a function of optical path length, infrared (IR) pulse energy and pa ...

Elsevier2011

The Orientation and Charge of Water at the Hydrophobic Oil Droplet-Water Interface

Sylvie Roke, Hilton Barbosa De Aguiar

We established the charge and structure of the oil/water interface by combining zeta-potential measurements, sum frequency scattering (SFS) and molecular dynamics simulations. The SFS experiments show that the orientation of water molecules can be followed ...

2011

Label-free spectroscopic detection of vesicles in water using vibrational sum frequency scattering

Sylvie Roke, Hilton Barbosa De Aguiar

Vibrational sum frequency scattering (SFS) has been used to study sub-micron, catanionic vesicles in solution. The vesicles were synthesized from a binary mixture of dodecyltrimethylammonium bromide (DTAB) and sodium dodecylsulfate (SDS) surfactants in deu ...

2011