Giovanni Verri

The Art institute of Chicago · Department of Art History

This paper discusses UV-induced luminescence imaging capturing parameters, including radiation sources and filters used in the field of cultural heritage. It also discusses factors complicating the interpretation of luminescence images. In particular, it provides: 1. A theoretical background for the capture of UV-induced luminescence images in rel...

6,6′-dibromoindigo (DBI) is the main component of Tyrian purple, or Imperial purple, one of the most controversial, sought-after and expensive colouring matters of antiquity. Evidence of its use, both as a pigment and as a dye, is found in the archaeological record, especially in the countries surrounding the Mediterranean basin. The photo-induced...

Wall paintings are complex, heterogeneous structures open to the environment and composed of multiple layers. Additionally, they are frequently located in remote areas, where basic infrastructure is not available. The causes and mechanisms involved in the complex deterioration phenomena, which wall paintings are often subjected to, are therefore di...

The widespread occurrence of Indian yellow on an early 17th-century wall painting in Rajasthan (India) was initially indicated by photo-induced luminescence imaging of the painted scheme in the Badal Mahal within the Garh Palace (Bundi). The presence of the organic pigment was subsequently confirmed by HPLC-ESI-Q-ToF. The results of a multi-analyti...

The optical properties (photophysics and imaging) of Indian yellow were investigated both in solid state and in aqueous solution and correlated with its chemical composition. The analyses were corroborated by a theoretical study carried out on the different xanthone derivatives that comprise the pigment under investigation, both as isolated molecul...

Infrared reflectography of the Mughal painting known as Princes of the House of Timur (British Museum, 1913,0208,0.1) suggests at least four phases of overpainting, reveals previously unseen inscriptions, clarifies issues of iconography, and provides parallels with workshop practice—in particular, with bookbinding and book illustration.

Manganese blue is a synthetic barium manganate(vi) sulphate compound that was produced from 1935 to the 1990s and was used both as a blue pigment in works of art and by conservators in the restoration of paintings. The photophysical properties of the compound are described as well as the setup needed to record the spatial distribution of the pigmen...

Bulk thermal alterations to chlorite schist occurring at temperatures above 450 °C are traditionally studied using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, or thermogravimetric analysis (TGA), but lower temperature changes that lead to structural and chemical alteration, including changes in oxidation state that are...

From the third century bc to the second century ad small detailed central panels (emblemata) made using the opus vermiculatum technique were used as focal points in larger mosaic pavements. They were custom made in stone or terracotta trays to facilitate their transport and placement. Although mosaic panels in opus vermiculatum have been discovered...

This contribution presents recent work on an important Roman marble head of the mid-second century ad from the collection of the British Museum (1884,0617.1). The head was found on the Esquiline Hill in Rome in 1884 and soon after its discovery was acquired for the British Museum. Unusually, it retained extensive traces of its original polychromy,...

Egyptian blue was extensively used throughout the areas surrounding the Mediterranean from early dynastic Egypt until after the Roman Empire ended. A new, easily applied, technique to detect and map this pigment has been developed that takes advantage of its very strong photo-induced infrared luminescence. Using this method, single particles of pig...

The variations of the fluorescence emission of carmine lake travelling through an absorbing and scattering medium, such as a paint layer, were investigated by ultraviolet (UV)-visible absorption, fluorescence spectroscopy, and imaging techniques. Samples of the lake were studied in dilute and saturated solutions, on a reference test panel and a rea...

The aim of this study is to develop a method for the non-invasive and in situ identification of organic binders in wall paintings by fiber optic mid-FTIR reflectance spectroscopy. The non-invasive point analysis methodology was set-up working on a wide set of wall painting replicas of known composition and using statistical multivariate methods, in...

Visible-induced luminescence imaging in the near infrared range (800-1700 nm) can play a key role in the spatial characterization of certain historical blue pigments (principally Egyptian blue, Han blue and Han purple). All three of these pigments show a very strong infrared emission when excited across the visible range. The setup required for thi...

Cuprorivaite (CaCuSi(4)O(10), also known as Egyptian blue) exhibits an exceptionally high emission quantum efficiency in the near-infrared region (lambda(max) = 910 nm, Phi(EM) = 10.5%) and a long excited state lifetime (107 mus); these properties make it appealing for several applications in the fields of biomedical analysis, telecommunications an...

The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of vi...

Ultraviolet-induced fluorescence spectroscopy is a commonly used technique for the characterization and identification of painting materials, such as organic binders and colorants. Its interpretation is strictly connected to both the experimental setup and an understanding of the physical and chemical interactions among materials in paint layers, w...

The unfinished drawing Virtus Combusta (virtue in flames) by Andrea Mantegna has been studied as part of a wider project to examine and analyse Italian fifteenth-century drawings for a future exhibition. Preliminary examination under magnification was followed by visible, infrared and UV-induced visible luminescence imaging. The drawing materials w...

A group of 17 Italian fifteenth-century metalpoint drawings were examined using near-infrared reflectography and analysed non-invasively by X-ray fluorescence and Raman spectrometry. Metals, including silver and lead, reflect infrared (IR) radiation specularly and selectively. As expected, all of the lead-based metalpoint in this group of drawings...

Although digital multispectral imaging-particularly ultraviolet-induced fluorescence imaging-is a very common examination tool, its interpretation remains fraught with difficulties. Interpretation is strongly dependent on the capture methodology, requires an understanding of the physical and chemical characteristics and interactions among materials...

The in situ produced cosmogenic beryllium isotope, 10Be, in flint artifacts from different layers in prehistoric caves can provide information on flint procurement. The buildup of 10Be in a flint matrix is related to the exposure time of the flint to cosmic rays. Although this exposure history can be complex, the 10Be content of flint assemblages c...

The AMS facility based on a 14UD Pelletron tandem accelerator has been upgraded in recent years to support an active and diversified research program. A new dedicated AMS ion source beam line merging at 45° with the existing injection line through a 45° electrostatic deflector is in operation. The multi-sample high-intensity Cs sputter ion source s...

The development of mining to acquire the best raw materials for producing stone tools represents a breakthrough in human technological and intellectual development. We present a new approach to studying the history of flint mining, using in situ-produced cosmogenic 10Be concentrations. We show that the raw material used to manufacture flint artifac...

Among the many production and destruction nuclear reactions that bear on the net 44Ti yield in the supernova environment, recently highlighted by γ-ray astronomy observations, the α capture on 40Ca stands out in the α-rich freezeout phase conjectured by astrophysical models. We activate a He-gas target with a 40Ca beam and implant recoiling 44Ti nu...

By exploiting the gamma detector-shielding configuration in a plasma focus (PF) device dedicated to fast-neutron activation analysis of gold, a reliable neutron counter may be established. The decay of 207Pbm induced by neutrons in the lead shielding surrounding the photon detector produces gamma photons of 569.7 and 1063.6 keV, which peaks are reg...

It has been shown [1] that an m = 0 instability of a Z-pinch carrying a current of the order of 10 MA, with a rise time inferior to 10 nsec can generate a spark capable of igniting a fusion detonation in the adjacent D-T plasma channel. A possible method for generating such currents, necessary for the implosion of an initial large radius, low tempe...

The spark created in a neck of a dense Z-pinch can ignite a fusion detonation in the adjacent D-T plasma channel. Using an appropriate transition between the ignited D-T plasma and an inertially confined cylinder of highly compressed advanced fuel plasma it is possible to amplify the spark energy to a level adequate for the ignition of a detonati...

The behaviour of Pb activation peaks, which appear in an X-ray spectrum of Fast Neutron Activation Analysis (FNAA) performed by means of a Plasma Focus (PF) neutron source and an NaI scintillator counter, has been studied. The PF device generates neutron bursts of different intensities. To know the exact neutron flux illuminating a sample during PF...

Plasma derived flash X-ray sources may find potential applications in medicine and industry. Notwithstanding, as is the case of Plasma Focus (PF) devices, their characterisation in term of photon energy, temporal and spatial beam stability is far to be considered satisfactory. In this work, a radiographic approach, which avoids the effects caused b...

A model of energy transfer from a heavy slow liner to a light and fast one is presented. Simple criteria for the optimum mass ratio of the two liners are derived and made more precise by a numerical solution of the equations of motion. Practical limitations and an application to inertial confinement fusion are mentioned.

The application of a Fast Neutron Activation Analysis (FNAA) technique on samples of pure gold, irradiated by a plasma focus of 7 kJ, has been investigated. The reaction was the inelastic scattering of neutrons, 197Au(n,n′γ)197Aum. To avoid problems connected with peculiar features of the neutron emission from this kind of source, a preliminary sta...

The application of a Fast Neutron Activation Analysis (FNAA) technique on samples of pure gold, irradiated by a plasma focus of 7 kJ, has been investigated. The reaction was the inelastic scattering of neutrons, Au-197(n,n'gamma)Au-197(m). To avoid problems connected with peculiar features of the neutron emission from this kind of source, a prelimi...