title: Multianalytical Study of Historical Luminescent Lithopone for the Detection of Impurities and Trace Metal Ions.
abstract: We have explored the performance of an integrated multianalytical approach to the analysis of a series of microsamples of historical lithopone (a coprecipitate of ZnS + BaSO4) produced at the beginning of the 20th century, based on the combination of spectrally- and lifetime-resolved photoluminescence (PL) microscopy imaging and electron paramagnetic resonance (EPR) spectroscopy. Multispectral imaging of the PL emission from microsamples revealed the presence of different luminescence centers emitting in the visible spectrum, which we have hypothesized as trace Cu and Mn impurities unintentionally introduced into the ZnS crystal lattice during synthesis, which act as deep traps for electrons. Time-resolved PL imaging analyses highlighted the microsecond decay-kinetic behavior of the emission, confirming the trap state nature of the luminescence centers. EPR confirmed the presence of Cu and Mn, further providing information on the microenvironment of defects in the ZnS crystalline lattice related to specific paramagnetic ions. The multianalytical approach provides important insights into the historical synthesis of lithophone and will be useful for the rapid screening and mapping of impurities in complex semiconductor pigments and other artists' materials.
authors.affiliation: †Istituto di Fotonica e Nanotecnologie - Consiglio Nazionale delle Ricerche (CNR-IFN), Piazza Leonardo da Vinci 32, Milano, 20133 Italy.|‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133 Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Bellei
authors.affiliation: †Istituto di Fotonica e Nanotecnologie - Consiglio Nazionale delle Ricerche (CNR-IFN), Piazza Leonardo da Vinci 32, Milano, 20133 Italy.
authors.forename: Austin
authors.initials: A
authors.lastname: Nevin
authors.affiliation: ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133 Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Cesaratto
authors.affiliation: ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133 Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Capogrosso
authors.affiliation: §Laboratoire de Spectrochimie Infrarouge et Raman (LASIR), UMR CNRS 8516, Université de Lille 1 Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Vezin
authors.forename: Caroline
authors.initials: C
authors.lastname: Tokarski
authors.affiliation: ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133 Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Valentini
authors.affiliation: ‡Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133 Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Comelli