arXiv subjects

Barbara Federica Scremin

Publications and source records attributed to Barbara Federica Scremin.

3 recordsLinked to original sources

arXiv2017

Tetrathiafulvalene radical cation (TTF+.) Charge Transfer aggregates included in PMMA matrix, a Resonance Raman Study

TTFClO4 salts were included in a PMMA matrix via solvent casting technique under vacuum, up to 72 hours of pumping. The synthesis of the salt, present in the literature was enriched with a further purification procedure, wich resulted important to obtain TTF+. radical cation aggregates. The thin films were characterized by low temperature UV-VIS-NIR absorption, and a multicomponent broad charge transfer band (CT) in the near infrared was found. Raman spectroscopy (RRS) in resonance with the CT transition allowed to study the origin of the CT absorption: the species present in the films were recognized as dimers and aggregates of TTF+. radical cation.

physics.chem-ph↗

arXiv2017

Nonlinear absorption of tetrathiafulvalene radical cation (TTF+) based charge transfer (CT) aggregates in PMMA

Nolinear Absorption of CT TFF+ aggregates in PMMA matrix was studied with resonant excitation around 800 nm in the femtoseconds regime with the Z-Scan technique with 100 Hz pulse repetition rate. The saturated absorption profiles were fitted with a prepared formula based on steady state rate equations for a homogeneous ensemble of two levels systems, thin samples and quasi monochromatic field without the usual assumption of low saturation regime. The lifetime of the CT state, with the use of this model was estimated in hundred of fs, of the same order of magnitude of the exciting pulse.

physics.chem-ph↗

arXiv2016

Raman study of a work of art fragment

The purpose of the present report was the study and identification of an unspecified sample on a work of art by means only of a microscope coupled to a Raman spectrometer. The origin of the fragment was unknown. The Raman spectra on the virgin sample were giving no results because of a deteriorated surface treatment, in spite of the evident blue color identified by microscopic visual inspection. The sample fragmentation and the preparation of a KBr pellet allowed the distribution of the painting layers of the different components on a flat substrate reducing surface effects. Selecting the areas of different color and focusing there it was possible to identify the pigments from their Raman spectra locally acquired by selective excitation. Raman spectra were assigned by comparison with published databases. It was possible to connect Carbon Black and Orange iron oxide, as documented historically, as constituents of Azurite preparatory layer Morellone, according to a technique generally employed to allow the use of Azurite blue pigment on frescos, consequently the identification of typology of work of art was deducted and attributed to a fresco.

physics.ed-ph↗