Mesoporous silica photoluminescence properties in samples with different pore size

Anedda, Alberto; Carbonaro, Carlo Maria; Clemente, Francesca; Corpino, Riccardo; Ricci, Pier Carlo

doi:10.1016/j.msec.2003.09.077

Cited by 11 publications

(14 citation statements)

References 17 publications

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“…The time-dependent PL decay is not described by a single decay lifetime (that is, it does not follow a single-exponential decay function) while good fitting is obtained with a double-exponential function, as in the case of other TRPL experiments on mesoporous SiO 2 . [22] Fitting the data by means of a double-exponential function I(t) ¼ A 1 exp(Àt/t 1 ) þ A 2 exp(Àt/t 2 ), decay lifetimes of the order of 1 and 10 ns respectively are obtained, similarly to findings reported for sol-gel synthesized mesoporous silica samples. [23] By changing the concentrations of NO 2 in the test chamber, no significant variations in the recombination dynamics were observed, as the PL lifetimes were found to be unaffected by the presence of nitrogen dioxide in the range from 1 to 50 ppm.…”

Section: Full Papersupporting

confidence: 75%

“…The violet emission is predominantly observed in fresh stoichiometric a-SiO 2 films and in mesoporous silica samples prepared by sol-gel synthesis. [22,25] It is believed to originate from surface centers [22,23,25,26] and is due to the fact that it can be significantly quenched (or even totally disappear) when the sample surface releases H 2 and H 2 O [24] (which may occur, for instance, during annealing at high temperatures); it has been correlated to the presence of Si-OH bonds, although a precise attribution to specific centers has not been established definitely. In our case (Fig.…”

Section: Discussionmentioning

confidence: 99%

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The Gas‐Detection Properties of Light‐Emitting Diatoms

Lettieri

Setaro

Stefano³

et al. 2008

Adv Funct Materials

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In recent years, the porous silica structures (frustules) created by living diatoms have been studied for several nanoengineering applications based on biomimetic approaches. We focus on the gas‐sensing properties of diatoms: investigation of different species shows that the photoluminescence emission of frustules is affected by even small modifications of the surrounding gas environment, exhibiting a detection limit of few tenths of ppm in the case of nitrogen dioxide. A new understanding of this phenomenon is discussed here in terms of “static‐type” luminescence quenching through suppression of radiative states (most probably surface oxygen vacancies) induced by adsorption of gas molecules. The modeling allows the free energy of desorption to be measured by all‐optical means: the value obtained suggests that a chemisorption process is involved, in agreement with the observed absorption/desorption kinetics. The findings encourage investigation of diatoms as low‐cost biological transducers for detection of gas species.

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Section: Full Papersupporting

confidence: 75%

Section: Discussionmentioning

confidence: 99%

The Gas‐Detection Properties of Light‐Emitting Diatoms

Lettieri

Setaro

Stefano³

et al. 2008

Adv Funct Materials

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“…Indeed, Anedda et al . demonstrated that the spectral distribution of the PL signal depends on the pore diameter, which was attributed to changes in the bonding energies by the interaction in close proximity of the Si–OH and O–H groups, reinforcing their electrostatic interaction and consequently affecting their electronic levels at higher or lower energies, in particular, in the green region of the spectrum, which may explain the enhancement of this region emission observed in Figure .…”

Section: Discussionmentioning

confidence: 91%

“…However, in Anedda et al . 's work , the broad emission results because their porous material showed a non‐uniform broad distribution of pore diameters; thus, the final featureless broad curve, or at most composed of two broad emission PL curves, results from the envelope for all pores which forms a continuous distribution in pore diameter.…”

Section: Discussionmentioning

confidence: 93%

Photoluminescence shift in frustules of two pennate diatoms and nanostructural changes to their pores

et al. 2014

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The diatom silicified cell wall (frustule) contains pore arrays at the micro- to nanometer scale that display efficient luminescence within the visible spectrum. Morphometric analysis of the size and arrangement of pores was conducted to observe whether any correlation exists with the photoluminescence (PL) of two diatom species of different ages. UV-excited PL displays four clearly defined peaks within the blue-region spectrum, on top of the broad PL characteristic of synthetic porous silicon dioxide, recorded for reference and where discrete lines are absent. A set of shifted emission lines was observed when diatom cultures reached adulthood. These discrete line shifts correlate with structural changes observed in adult frustules: reduction in pore diameter; appearance of pores within pores, 10 nm in size; an increase in the gap distance between stria; and the deposition of several girdle bands with a concomitant increase in the diatom waist length, as well as the appearance of pores on such bands. Destruction of the pores results in the disappearance of all discrete emission lines. The PL shifts are correlated with a substantial increment of Si-OH groups adsorbed on the frustule surface, as revealed by Fourier transform infrared spectroscopy.

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“…[30,33,37] In the last years our endeavor has been dedicated to the characterization of the optical features of mesoporous silica, an ideal benchmark of nanostructured silica with very large specific surface area, up to 600 m 2 /gr in the investigated samples, and skeleton walls in the nanometer range. [17,26,27,34,35,[45][46][47][48][49][50][51] The emission properties in the UV and blue range have been investigated as a function of the pore diameter, by considering the hydrophilic character of the silica surface, [17,46] and as a function of different environment conditions, by analyzing the effects of long air exposure, [51] vacuum treatment, [49] oxygen or nitrogen purging and interaction with strongly oxidizing polar solvent (H 2 O 2 ). [34,35] In the present work we collect all the results gathered in our research, including some new experiments with protic and aprotic solvents, and discuss them in the framework of the proposed models.…”

Section: Introductionmentioning

confidence: 99%

On the origin of blue and UV emission bands in mesoporous silica

Carbonaro

Corpino²,

Ricci³

et al. 2014

AIP Conference Proceedings

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Abstract. In this paper we present a review of the main results we obtained studying the emission properties of mesoporous silica in the UV-VIS range. Two main emission bands were investigated, the blue one, peaked in the 400-450 nm range, and the UV one, centered at about 300-350 nm, both excited in the UV and vacuum UV range. The origin of the two bands, investigated through optical spectroscopy techniques, is discussed in terms of possible surface emitting centers probing the samples with different chemical and physical treatments or exploiting different morphological and textural properties of the samples obtained by properly engineering the sol-gel synthesis.

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Mesoporous silica photoluminescence properties in samples with different pore size

Cited by 11 publications

References 17 publications

The Gas‐Detection Properties of Light‐Emitting Diatoms

The Gas‐Detection Properties of Light‐Emitting Diatoms

Photoluminescence shift in frustules of two pennate diatoms and nanostructural changes to their pores

On the origin of blue and UV emission bands in mesoporous silica

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