Open AccessTowards in situ fluorescence spectroscopy and microscopy investigations of asphaltene precipitation kinetics
Author(s) -
Juliana Crotti Franco,
Grasiele Gonçalves,
Monique Souza,
Samantha B C Rosa,
Larissa M Thiegue,
Teresa Dib Zambon Atvars,
Paulo de Tarso Vieira e Rosa,
René A. Nome
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.030874
Subject(s) - asphaltene , microscopy , fluorescence spectroscopy , materials science , spectroscopy , raman spectroscopy , fluorescence , analytical chemistry (journal) , fluorescence microscope , time resolved spectroscopy , optical microscope , precipitation , fluorescence correlation spectroscopy , optics , chemistry , scanning electron microscope , chromatography , physics , organic chemistry , quantum mechanics , meteorology , composite material
We perform a spectroscopic analysis of asphaltene in solution and in crude oil with the goal of designing an optical probe of asphaltene precipitation inside high-pressure cells. Quantitative analysis of steady-state spectroscopic data is employed to identify fluorescence and Raman contributions to the observed signals. Time-resolved fluorescence spectroscopy indicates that fluorescence lifetime can be used as a spectroscopic probe of asphaltene in crude oil. Quantitative confocal laser-scanning microscopy studies of asphaltene in n-heptane are used to calculate particle-size distributions as a function of time, both at the sample surface and asphaltene interior. The resulting precipitation kinetics is well described by stochastic numerical simulations of diffusion-limited aggregation. Based on these results, we present the design and construction of an apparatus to optically probe the in situ precipitation of asphaltene suitable for studies inside high pressure cells. Design considerations include the use of a spatial light modulator for aberration correction in microscopy measurements, together with the design of epi-fluorescence spectrometer, both fiber-based and for remote sensing fluorescence spectroscopy.