Graphene, a single layer of carbon atoms, is the archetype of a new class of materials, the so-called bidimensional systems. Stronger than steel, flexible as much as plastic and lighter than aluminium, it shows better thermal and electrical properties than copper. These features, concurring in the same material, have aroused great interest in the scientific community. In 2013, one of the largest research programme ever launched in Europe (Graphene Flagship) began: it provides a one-billion funding for 10 years at the aim to spread the use of graphene from the laboratory to our daily life.

A research team from Department of Physics of Sapienza University of Rome, in collaboration with Cambridge University, Politecnico of Milan and CNR, unveiled the effects of ultrafast light exposure (laser pulses with a time duration shorter than one-millionth of a millionth of second) on the interaction processes between charge carriers and nuclei oscillations, observed for the first time from the atomic lattice perspective. The possibility to manipulate the charge carriers (electrons) distribution by means of external perturbations paves the way to several applications in different fields.

“The application of ultrashort light pulses - Tullio Scopigno, coordinator of the research, says - allows inducing a thermodynamic out-of-equilibrium regime. Indeed, upon applying an ultrashort electromagnetic field, the electronic temperature rises significantly above the lattice one. This, in turn, implies fundamental modifications in the way the lattice vibrations interact with the charge carriers”. This work has noteworthy implications for the emerging field of low dimensional materials-based photonics, i.e. in devices such as solar cells, LED, touchscreen, photodetectors and pulsed laser sources. For this latter application, an innovative microscope system for biomedical studies is under patenting.

References:
Raman spectroscopy of graphene under ultrafast laser excitation - C. Ferrante, A. Virga, L. Benfatto, M. Martinati, D. De Fazio, U. Sassi, C. Fasolato, A. K. Ott, P. Postorino, D.Yoon, G. Cerullo, F. Mauri, A. C. Ferrari, T. Scopigno - Nature Communications, 9, 308, (2018)  doi:10.1038/s41467-017-02508-x

Further Information
Tullio Scopigno
T (+39) 0649913314