Soft Matter Physics @ LENS
We are a group of researchers working at the European Lab. for Non-Linear Spectroscopy (LENS), University of Firenze in Italy. We are studying complex materials, mainly soft matter by laser spectroscopy. In this site you can find a very short summary of our present and past work.
Our research interest is on the experimental investigation of "Soft Matter Physics", this focuses on the study of a variety of physical systems whose properties are intermediate between liquid and solid states. All these materials, despite their very different nature, share an important common physical feature: soft matter self-organizes into mesoscopic structures that are much larger than the microscopic scale and yet are much smaller than the macroscopic (overall) scale of the material. At LENS we study structure and dynamics of soft matter by means time-resolved laser spectroscopy, exciting the sample impulsively. It is thus possible to follow the sample response over a very wide time scale, from picosecond to millisecond, and investigate a variety of soft matter properties, including molecular vibrations, structural-rotational relaxation, elastic-acoustic propagation and thermal diffusion.
For information you can contact:
Renato Torre
Dynamics of Liquid Water: recent experimental investigations
Modification of local and collective dynamics of water in perchlorate
solution, induced by pressure and concentration
C. Calvagna , ..., and Renato Torre
Journal of Molecular Liquids 337 (2021) 116273
Pressure Effects on Water Dynamics by Time-Resolved Optical Kerr Effect
A.Taschin, P. Bartolini, S. Fanetti, A.Lapini, M.Citroni, R.Righini, R.Bini and Renato Torre
J. Phys. Chem. Lett. 11 (2020) 3063
Vibrational Spectroscopy and Dynamics of Water
Perakis, F.; Marco, L.; Shalit, A.; Tang, F.; Kann, Z. R.; Kuhne, T. D.; Torre, R.; Bonn, M.; Nagata, Y.
Chem Rev 116 (2016), 7590–7607.
Optical Kerr Effect of Liquid and Supercooled Water: The Experimental and Data Analysis Perspective.
A. Taschin, P. Bartolini, R. Eramo, R. Righini, and R. Torre.
Journal of Chemical Physics,141 (2014) 084507.
Evidence of two distinct local structures of water from ambient to supercooled conditions.
A.Taschin,P. Bartolini, R. Eramo, R. Righini, and R. Torre,
The liquid and supercooled states of water show a series of anomalies whose nature is debated. A key role is attributed to the formation of structural aggregates induced by critical phenomena occurring deep in the supercooled region; the nature of the water anomalies and of the hidden critical processes remains elusive. We used a time-resolved optical Kerr effect investigation of the vibrational dynamics and relaxation processes in supercooled bulk water.
Recently, we presented an overview of time-resolved vibrational spectroscopic studies of liquid water from ambient conditions to the supercooled state. The structure and dynamics of the complex hydrogen-bond network formed by water molecules are discussed, as well as the dissipation mechanism of vibrational energy throughout this network. A broad range of water investigations are addressed:infrared and Raman spectroscopy, femtosecond pump−probe, photon-echo, optical Kerr effect, sum-frequency generation, and two-dimensional infrared spectroscopic studies. By comparison of the complementary aspects probed by various linear and nonlinear spectroscopic techniques, a coherent picture of water dynamics and energetics emerges.
Protein Self-Assembling Dynamics
Multi-length scale structural investigation of lysozyme self-assembly
S. Catalini, ...., R. Mezzenga and Renato Torre. iScience 25 (2022) 104586
Probing Globular Protein Self-Assembling Dynamics by Heterodyne Transient Grating Experiments
S. Catalini, A. Taschin, P. Bartolini, P. Foggi and Renato Torre. Appl. Sci. 9 (2019) 405
Self-assembling phenomena of biomolecules are characterized by different steps, in which the conformational rearrangements and intermolecular associations drive the formation of stable structures of increasing complexity (e.g. amyloid fibrils, hydrogel networks, ...). Protein-based hydrogels have recently received great attention since they can be the key to develop novel biomaterials. In fact, hydrogels have the capability to retain inside their matrix a great amount of water (up to 97%), which make these materials similar to biological tissues. Protein hydrogels are therefore of great interest in many fields spanning from the medical to the nanotechnological. We undertaken a systematic study of self-assembling phenomena taking place in biologic samples by means of different spectroscopic investigation, e.g HD-TG, OKE of THz measurements as a function of the environmental conditions.
Transport phenomena at the nanoscale investigated by pulsed x-ray
Hard X-ray transient grating spectroscopy on bismuth germanate
Jérémy R. Rouxel et al.
Nature Photonics, https://doi.org/10.1038/s41566-021-00797-9
To date, the modeling and understanding of transport phenomena at the nanoscale remains an open problem in materials science. Physical modeling fails to describe some of the most relevant transport phenomena when they are characterized by nanometric wavelengths, e.g. the propagation of very high frequency acoustic or phonon modes in the THz band, or thermal propagation on the nanoscale. Furthermore, the miniaturization of devices reached the nanoscale demanding an operational understanding of the different transport processes at this length scale.
The poor understanding of these phenomena is strongly due to the lack of experimental investigations capable of probing the transport processes on such a reduced length scale. This requires the use of short wavelength radiation, and in particular X-rays. The main challenge is to control multiple X-ray beams to generate a coherent interaction with matter at the nanoscale, in order to perform spectroscopy. non-linear X-ray.
As members of an international consortium of researchers, using the ultrafast X-ray pulse generated by a free electron laser at the Paul Scherrer Institut, Switzerland. In a recent paper, we achieved to implement a 4-wave X-ray mixing technique with a sub-picosecond time and sub-micrometric spatial resolutions. A transient periodicity lattice of about 700 nm is generated in a germinated bismuth sample and its temporal decay is measured from femtoseconds to picoseconds of delay, revealing the phononic response of the material.This is the first demonstration of hard X-ray transient grating spectroscopy (XTG), it opens the way to exciting and novel developments. Indeed, hard X-ray TG is uniquely suited to investigate nanoscale transport phenomena in bulk and nanostructured materials, in disordered materials and even in liquids. Future experiments are deemed to open the field to applications in the characterization of materials, in particular for nano-electronics, nano-optics and nano-magnetism.
Time-domain THz spectroscopy
..... new THz set-up
THz time-domain spectroscopic investigations of thin films.Taschin, A.; Bartolini, P.; Tasseva, J.; Torre, R. Measurement, 118 (2018), 282-288,
- Bone investigations
New investigation techniques are constantly required to better characterize bone ultrastructure, we provide an extended investigation of the vibrational features of bone tissue in the 0.1-3 THz frequency range by time-domain THz spectroscopy supported by a combination of X-ray diffraction and DFT-normal modes calculations. In particular, we investigate the effect of heating on bone tissue and synthetic calcium-phosphates compounds with close structure and composition to bone mineral. We thus demonstrate that the narrow vibrational mode at 2.1 THz in bone samples exposed to thermal treatment from a lattice mode of stoichiometric hydroxyapatite. The THz spectral range therefore provides a clear signature of the crystalline state of the investigated bone tissue and could, therefore be used to monitor or identify structural transitions occurring in bone upon heating.
Time-domain THz spect. of the characteristics of hydroxyapatite provides a signature of heating in bone tissue.
Plazanet M, Tasseva J, Bartolini P, Taschin A, Torre R, Combes C, et al.
- Artwork investigations
THz pulse imaging and spectroscopy is an emerging non-invasive method for the characterization of cultural heritage artefacts that provides complementary information to traditional analytical tools.We explored artworks drawing materials with THz-Time Domain Spectroscopy (THz-TDS) extending the investigation to thin layers of inks, that was never realized previously. We developed a new speci.c experimental method and data analysis to disentangle the multiple reflection signals. Thanks to a high signal to noise ratio and the accurate analysis implemented, our measurements enable the calculation of the absolute absorption coefficient and index of refraction of the materials, as well as the sample thickness down to tens of microns both in single layer and bilayer configurations.
Drawing materials studied by THz spectroscopy.
A. Taschin; P.Bartolini; J. Tasseva; J. Striova; R. Fontana; C. Riminesi; Renato Torre.
Thin layered drawing media probed by THz time-domain spectroscopy
J. Tasseva, A. Taschin, P. Bartolini, J. Striova, R. Fontana, R. Torre
- High-Precision Terahertz Spectroscopy
Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy
S. Bartalini, L. Consolino, P. Cancio, P. De Natale, P. Bartolini, A. Taschin, M. De Pas, H. Beere, D. Ritchie, M. S. Vitiello, and R. Torre