A sustainable strategy of redistribution of the tourist flows in Basilicata region, in south Italy. Coastal tourism as a development factor for the natural parks.

Basilicata region, in south Italy, is delimited by the Ionian and the Tyrrhenian seas and  includes territories morphologically different with four protected areas, two regional and two national. This lack of homogeneity of the territory reflects on the tourism dynamics of the region. Coastal territories are more profitable in terms of flows, while in the inland territories, except Matera, the weight of tourism is still too low. In the protected areas, except the Regional Park of Murgia Materana, flows are marginal and tourism cannot activate a significant local development process. Given this framework, the Fondazione Mattei conducted a study aiming at the determination of strategic guidelines for the planning of a local development based on the integration between market forces and forms of social control. This planning aims at the redistribution and deseasonalization of coastal flows through the integration between coastal and rural tourism in the inland. To evaluate the integrated tourism product potentiality, Eni Enrico Mattei foundation analyzed some national case studies and conducted a survey on the consumer of the Ionian Coast. Analysis measured the tourism competitiveness of the protected areas in Basilicata by the use of Dwyer and Kim’s model combined with Balanced Scorecard method. The more appealing products for the coastal demand and more competitive products in the market of green destinations have been identified by BCG matrix.The analysis outlined the necessity of a strategy of integration of the four protected areas in order to increase their market share and several tourism segments should be enhanced to increase the potential of the nature-based tourism product of Basilicata

Transverse dynamics of water across the melting point: A parallel neutron and x-ray inelastic scattering study

Joint inelastic neutron and x-ray scattering measurements have been performed on heavy water across the melting point. The spectra bear clear evidence of low- and high-frequency inelastic shoulders related to transverse and longitudinal modes, respectively. Upon increasing the momentum transfer, the spectral shape evolves from a viscoelastic regime, where the low-frequency mode is clearly over-damped, toward an elastic one where its propagation becomes instead allowed. The crossover between the two regimes occurs whenever both the characteristic frequency and the linewidth of the low-frequency mode match the inverse of the structural relaxation time. Furthermore, we observe that the frequency of the transverse mode undergoes a discontinuity across the melting, whose extent reduces upon increasing the exchanged momentum

Stimulated Brillouin scattering at 1 nm-1 wavevector by extreme ultraviolet transient gratings

We crossed two femtosecond extreme ultraviolet (EUV) pulses in a beta - Ga2O3 (001) single crystal to create transient gratings (TG) of light intensity with sub-100 nm spatial periodicity. The EUV TG excitation launches phonon modes, whose dynamics were revealed via the backward diffraction of a third, time-delayed, EUV probe pulse. In addition to the modes typically observed in this kind of experiment, the phase-matching condition imposed by the TG, combined with the sharp penetration depth of the EUV excitation pulses, permitted to generate and detect phonons with a wavevector tangibly larger (approximately 1 nm-1) than the EUV TG one, via stimulated Brillouin back-scattering (SBBS) of the EUV probe. While SBBS of an optical probe was reported in previous EUV TG experiments, the extension of SBBS to short wavelength radiation can be used as a contact-less experimental tool for filling the gap between the wavevector range accessible through inelastic hard X-ray and thermal neutron scattering techniques, and the one accessible through Brillouin scattering of visible and UV light.Comment: 7 pages, 3 figure

Signature of a polyamorphic transition in the THz spectrum of vitreous GeO2

The THz spectrum of density fluctuations, $S(Q, \omega)$, of vitreous GeO$_2$ at ambient temperature was measured by inelastic x-ray scattering from ambient pressure up to pressures well beyond that of the known $\alpha$-quartz to rutile polyamorphic (PA) transition. We observe significant differences in the spectral shape measured below and above the PA transition, in particular, in the 30-80 meV range. Guided by first-principle lattice dynamics calculations, we interpret the changes in the phonon dispersion as the evolution from a quartz-like to a rutile-like coordination. Notably, such a crossover is accompanied by a cusp-like behavior in the pressure dependence of the elastic response of the system. Overall, the presented results highlight the complex fingerprint of PA phenomena on the high-frequency phonon dispersion.Comment: 18 pages, 5 figure

Optical constants modelling in silicon nitride membrane transiently excited by EUV radiation.

We hereby report on a set of transient optical reflectivity and transmissivity measurements performed on silicon nitride thin membranes excited by extreme ultraviolet (EUV) radiation from a free electron laser (FEL). Experimental data were acquired as a function of the membrane thickness, FEL fluence and probe polarization. The time dependence of the refractive index, retrieved using Jones matrix formalism, encodes the dynamics of electron and lattice excitation following the FEL interaction. The observed dynamics are interpreted in the framework of a two temperature model, which permits to extract the relevant time scales and magnitudes of the processes. We also found that in order to explain the experimental data thermo-optical effects and inter-band filling must be phenomenologically added to the model

Transient grating spectroscopy on a DyCo5_5 thin film with femtosecond extreme ultraviolet pulses

Surface acoustic waves (SAWs) are excited by femtosecond extreme ultraviolet (EUV) transient gratings (TGs) in a room-temperature ferrimagnetic DyCo$_5$ alloy. TGs are generated by crossing a pair of EUV pulses from a free electron laser (FEL) with the wavelength of 20.8\,nm matching the Co $M$-edge, resulting in a SAW wavelength of $\Lambda=44$\,nm. Using the pump-probe transient grating scheme in a reflection geometry the excited SAWs could be followed in the time range of -10 to 100\,ps in the thin film. Coherent generation of TGs by ultrafast EUV pulses allows to excite SAW in any material and to investigate their couplings to other dynamics such as spin waves and orbital dynamics

Characterization of ultrafast free-electron laser pulses using extreme-ultraviolet transient gratings

The characterization of the time structure of ultrafast photon pulses in the extreme-ultraviolet (EUV) and soft X-ray spectral ranges is of high relevance for a number of scientific applications and photon diagnostics. Such measurements can be performed following different strategies and often require large setups and rather high pulse energies. Here, high-quality measurements carried out by exploiting the transient grating process, i.e. a third-order non-linear process sensitive to the time-overlap between two crossed EUV pulses, is reported. From such measurements it is possible to obtain information on both the second-order intensity autocorrelation function and on the coherence length of the pulses. It was found that the pulse energy density needed to carry out such measurements on solid state samples can be as low as a few mJ cm−2. Furthermore, the possibility to control the arrival time of the crossed pulses independently might permit the development of a number of coherent spectroscopies in the EUV and soft X-ray regime, such as, for example, photon echo and two-dimensional spectroscopy

Towards jitter-free pump-probe measurements at seeded free electron laser facilities

X-ray free electron lasers (FEL) coupled with optical lasers have opened unprecedented opportunities for studying ultrafast dynamics in matter. The major challenge in pump-probe experiments using FEL and optical lasers is synchronizing the arrival time of the two pulses. Here we report a technique that benefits from the seeded-FEL scheme and uses the optical seed laser for nearly jitter-free pump-probe experiments. Timing jitter as small as 6 fs has been achieved and confirmed by measurements of FEL-induced transient reflectivity changes of Si3N4 using both collinear and non-collinear geometries. Planned improvements of the experimental set-up are expected to further reduce the timing jitter between the two pulses down to fs level

Separation of kinetic rate orders in extreme ultraviolet transient grating spectroscopy

We present an Extreme Ultraviolet (EUV) transient grating (TG) experiment of the spinel Co3O4 compound using tuneable incident energies across the Co M2,3-edge and a 395 nm probe pulse, detecting both the first and the second diffraction orders. While the first diffraction order shows a monotonous behaviour as a function of time, with a sharp response at t=0, followed by a weak sub-picosecond component and a nearly constant signal thereafter, the time dependence of second diffraction order varies dramatically with the incident energy as it is tuned across the Co M-edge, with the appearance of a component at t>1 ps that grows with increasing energy. The results are rationalised in terms of the deviations of the initial grating from sinusoidal to non-sinusoidal, namely a flattening of the grating pattern, that introduces new Fourier components. These deviations are due to higher order, three-body terms in the population relaxation kinetics. These results highlight the use of the response of the second diffraction order in EUV TG as a tool to identify higher order terms in the population kinetics

Ultrafast dynamics in (TaSe4)2I triggered by valence and core-level excitation

Dimensionality plays a key role in the emergence of ordered phases, such as charge density-waves (CDW), which can couple to, and modulate, the topological properties of matter. In this work, we study the out-of-equilibrium dynamics of the paradigmatic quasi-one-dimensional material (TaSe4)2I, which exhibits a transition into an incommensurate CDW phase when cooled to just below room temperature, namely at TCDW = 263 K. We make use of both optical laser and free-electron laser (FEL) based time-resolved spectroscopies in order to study the effect of a selective excitation on the normal-state and on the CDW phases by probing the near-infrared/visible optical properties both along and perpendicularly to the direction of the CDW, where the system is metallic and insulating, respectively. Excitation of the core-levels by ultrashort X-ray FEL pulses at 47 eV and 119 eV induces reflectivity transients resembling those recorded when only exciting the valence band of the compound - by near-infrared pulses at 1.55 eV - in the case of the insulating sub-system. Conversely, the metallic sub-system displays relaxation dynamics which depend on the energy of photo-excitation. Moreover, excitation of the CDW amplitude mode is recorded only for excitation at a low-photon-energy. This fact suggests that the coupling of light to ordered states of matter can predominantly be achieved when directly injecting delocalized carriers in the valence band, rather than localized excitations in the core levels. Complementing this, table-top experiments allow us to prove the quasi-unidirectional nature of the CDW phase in (TaSe4)2I, whose fingerprints are detected along its c-axis only. Our results provide new insights into the symmetry of the ordered phase of (TaSe4)2I perturbed by a selective excitation, and suggest a novel approach based on complementary table-top and FEL spectroscopies for the study of complex materials