For the simultaneous monitoring by UVeVis and EXAFS, hydrolysis
and condensation reactions were carried out in a specially
designed liquid cell [23]. UVeVis data were recorded in the
240e540 nm wavelength range using the Varian Cary 50 dualbeam
spectrometer fitted with an optic fiber coupler connected
to an immersion probe during the first hours of reaction. The data
collectionwas carried out in a step scanning continuous way with a
step interval of 1 nm, an average time of 0.1 s per point and a time
framing of 1 min. UVeVis data were used to calculate the radius of
ZnO Q-dot from the effective mass model [1]. As fully explained in
Ref. [8] the average Q-dot radius can be obtained from the cutoff
wavelength determined by the intersection of the tangent of the
excitonic peak threshold with the wavelength axis after the
removal of the absorbance tail associated to the scattering effect.
Simultaneously, EXAFS measurements at the Zn K edge were
recorded at the SAMBA beamline at the Soleil synchrotron (Saint-
Aubin, France) in transmission mode using a Si(111) double crystal
monochromator with a collection time to about 210 s for a whole
XAFS spectra. Linear Combinations (LC) of normalized EXAFS
spectrum including the edgewere carried out in order to determine
the composition of the colloidal suspensions at any stage of the
reaction. Size-calibrated ZnO Q-dot and the initial zinc oxy-acetate
precursor solution before the addition of the base were used as
main components for simulating, by LC, the normalized EXAFS
spectra of colloidal suspensions during the ZnO formation and
growth. The software package Athena [24] was used to proceed the
analysis of the EXAFS data following the method fully explained in
Ref.