The exceptional near-infrared luminescence properties of cuprorivaite (Egyptian blue)

Accorsi, Gianluca; Verri, Giovanni; Bolognesi, Margherita; Armaroli, Nicola; Clementi, Catia; Miliani, Costanza; Romani, A.

doi:10.1039/b902563d

Cited by 165 publications

(157 citation statements)

References 28 publications

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“…1), in good agreement with the spectral data reported by others from pigments from the same supplier [7,19]. The emission lifetime measured in our commercial pigment is in agreement with Borozov et al [19] but differs with respect to that reported for the synthetic mineral calculated using single photon counting and 637 nm excitation (τ = 107 μs [6]). It is possible that the discrepancy in the PL lifetime is due to grinding of the pigment rather than to differences related to the methods used for the estimation of the PL decay [19].…”

Section: Resultssupporting

confidence: 81%

“…Whereas the PL properties of the naturally occurring cuprorivaite mineral have been widely investigated in terms of both spectrum and decay kinetics [3,6] and its brilliant emission has been exploited for the rapid detection of the presence of the pigment in artworks from the Ancient Egypt [7], the near-infrared emission in Egyptian blue-painted ancient objects is not completely understood [19]. The intense and long emission recorded with PL imaging which is on the order of 120 μs is nonetheless diagnostic for the presence of Egyptian blue.…”

Section: Discussionmentioning

confidence: 99%

“…While the fluorescence observed in madder lakes is due to the anthraquinone molecules purpurin and alizarin, the optical emission of Egyptian blue has been ascribed to Cu 2+ in a solid calcium-silica matrix [3][4][5]. Recent research on the mineral pigment has reported that synthetic cuprorivaite has a radiative emission with a maximum peaked at 910 nm and a lifetime of 107 μs and a quantum yield of 10 % [6].…”

Section: Introductionmentioning

confidence: 99%

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Dual wavelength excitation for the time-resolved photoluminescence imaging of painted ancient Egyptian objects

et al. 2016

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Background:The scientific imaging of works of art is crucial for the assessment of the presence and distribution of pigments and other materials on surfaces. It is known that some ancient pigments are luminescent: these include pink red-lakes and the blue and purple pigments Egyptian Blue (CaCuSi 4 O 10 ), Han blue (BaCuSi 4 O 10 ) and Han purple (BaCuSi 2 O 6 ). Indeed, the unique near-infrared luminescence emission of Egyptian blue allows the imaging of its distribution on surfaces. Results:We focus on the imaging of the time-resolved photoluminescence of ancient Egyptian objects in the Burri Collection from the Civic Museum of Crema and of the Cremasco (Italy). Time-resolved photoluminescence images have been acquired using excitation at 355 nm for detecting the ns-emission of red lakes and binding media; by employing 532 nm excitation Egyptian blue is probed, and the spatial distribution of its long-lived microsecond emission is imaged. For the first time we provide data on the photoluminescence lifetime of Egyptian blue directly from objects. Moreover, we demonstrate that the use of a pulsed laser emitting at two different wavelengths increases the effectiveness of the lifetime imaging technique for mapping the presence of emissions from pigments on painted surfaces. Laser-induced luminescence spectra from different areas of the objects and traditional digital imaging, using led-based lamps, long pass filters and a commercial photographic camera, complement the results from photoluminescence lifetime imaging. We demonstrate the versatility of a new instrumental setup, capable of recording decay emission kinetics with lifetimes from nanosecond to microseconds. Conclusions:While the combined wavelength approach for the imaging of emissions from different materials has been demonstrated for the study of ancient Egyptian pigments (both organic and inorganic), the method could be extended to the analysis of modern pigments and paintings.

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Section: Resultssupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dual wavelength excitation for the time-resolved photoluminescence imaging of painted ancient Egyptian objects

et al. 2016

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“…Strong light does not influence its colour either, as it may be observed in samples which have survived for millennia in both dry and damp environments and still exhibit an intense hue with no evidence of photobleaching. Recently, a further remarkable property of this pigment has been found, namely the exceptionally high level of emission quantum efficiency in the near infrared (λ max = 910 nm ; Φ EM = 10.5 %) and the long excited lifetime (107 μs), which makes cuprorivaite an excellent candidate as a luminescent label for a number of applications [12]. In view of this, we decided to investigate Egyptian blue non-linear behaviour.…”

Section: Description Of Samplesmentioning

confidence: 99%

Nonlinear optical imaging techniques (NLO) for painting investigation

Fovo¹,

Fontana²,

Striová³

et al. 2017

Proceedings of the International Conference LACONA XI

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Nonlinear optical imaging techniques (NLO imaging), i.e. multiphoton excitation fluorescence (MPEF), second and third harmonic generation (SHG, THG), are high-resolution imaging modalities which may provide non-destructive determination of thickness and composition within multi-layer objects as a function of depth. NLO techniques have been recently introduced into artworks analyses, giving promising results. As regards paintings, the guiding idea is to exploit the low absorption in the near-infrared (NIR) of most materials, using a laser light in this spectral region which may generate non-linear interactions within materials. The objective is to make feasible the in-depth profiling of thin films on the basis of refractive index changes, variation of optical activity and presence of fluorophores. Such information is definitely useful for the analysis of painted objects and can be also crucial for the monitoring of restoring operations. In this study, we present the preliminary results obtained through the application of NLO imaging techniques on a series of single-and multi-layers systems simulating real egg-tempera wood panel paintings. This research is part of the wider Iperion CH Project, whose WP6 entails the evaluation of NLO-imaging to obtain highly resolved en-face and 3D images of small areas on paintings. To that purpose, a set of multi-layer painted samples, simulating real paintings, was designed and realized. They are currently under analysis with different operating systems and modalities within the partnership. In order to assess the reliability of NLO measurements, data were complemented with other well-established techniques, such as Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Fluorescence (XRF) for the chemical characterization of materials, Optical Coherence Tomography (OCT) for the determination of layers thickness and laser scanning micro-profilometry for the study of surface morphology. In addition, colorimetric analyses, i.e. reflectance spectroscopy in the visible region, were performed in order to chromatically characterize pigments and lakes. Finally, the transparency of the different materials was investigated by means of Scanning Multispectral VIS-NIR Reflectography. The preliminary results suggest that the 740 nm wavelength, while enabling the visualization of the painting surfaces micromorphology, is not effective for the determination of thickness through the detection of the non-linear signals.

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“…This emission originates from the Cu 2+ in square planar coordination; these ions are linked by tetrahedral silicate moieties within the three-dimensional crystal structure, and the resulting layers alternate with alkali earth ions [4][5][6] . Recent technical highlights include NIR imaging to identify Egyptian and Han blue pigments on cultural heritage artifacts 7,8 , lanthanide doping of ACuSi 4 O 10 to enhance NIR reflectance properties and open new energy transfer pathways 9,10 , the use of ACuSi 4 O 10 as the active material for optical sensors 11 , and the exfoliation of CaCuSi 4 O 10 into monolayer nanosheets 12 .…”

Section: Introductionmentioning

confidence: 99%

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

Johnson-McDaniel

Salguero

2014

JoVE

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In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi 4 O 10 and BaCuSi 4 O 10 , the colored components of the historic Egyptian blue and Han blue pigments. The bulk forms of these materials are synthesized by both melt flux and solid-state routes, which provide some control over the crystallite size of the product. The melt flux process is time intensive, but it produces relatively large crystals at lower reaction temperatures. In comparison, the solid-state method is quicker yet requires higher reaction temperatures and yields smaller crystallites. Upon stirring in hot water, CaCuSi 4 O 10 spontaneously exfoliates into monolayer nanosheets, which are characterized by TEM and PXRD. BaCuSi 4 O 10 on the other hand requires ultrasonication in organic solvents to achieve exfoliation. Near infrared imaging illustrates that both the bulk and nanosheet forms of CaCuSi 4 O 10 and BaCuSi 4 O 10 are strong near infrared emitters. Aqueous CaCuSi 4 O 10 and BaCuSi 4 O 10 nanosheet dispersions are useful because they provide a new way to handle, characterize, and process these materials in colloidal form.

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The exceptional near-infrared luminescence properties of cuprorivaite (Egyptian blue)

Cited by 165 publications

References 28 publications

Dual wavelength excitation for the time-resolved photoluminescence imaging of painted ancient Egyptian objects

Dual wavelength excitation for the time-resolved photoluminescence imaging of painted ancient Egyptian objects

Nonlinear optical imaging techniques (NLO) for painting investigation

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

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