Smartphones are increasingly used in higher education and at university in mechanics, acoustics, and even thermodynamics as they offer a unique way to do simple science experiments. In this article, we show how smartphones can be used in fluid mechanics to measure surface tension of various liquids, which could help students understand the concept of surface tension through simple experiments.

The ultrafast electron energy transport is investigated in laser-heated warm dense copper in a high flux regime (2.5 AE 0.7 × 10 13 W=cm 2 absorbed). The dynamics of the electron temperature is retrieved from femtosecond time-resolved x-ray absorption near-edge spectroscopy near the Cu L3 edge. A characteristic time of ∼1 ps is observed for the increase in the average temperature in a 100 nm thick sample. Data are well reproduced by two-temperature hydrodynamic simulations, which support energy transport dominated by thermal conduction rather than ballistic electrons.

Exploring and understanding ultrafast processes at the atomic level is a scientific challenge. Femtosecond X-ray Absorption Near-Edge Spectroscopy (XANES) arises as an essential experimental probing method, as it can simultaneously reveal both electronic and atomic structures, and thus potentially unravel their non-equilibrium dynamic interplay which is at the origin of most of the ultrafast mechanisms. The key point of this investigation is the achievement of a femtosecond X-ray source suitable for routine experiments. This paper will show the progressive development and improvement of such laser-plasma-based X-ray sources, starting from the picosecond down to the femtosecond scale. Time-resolved XANES measurements have been achieved and interpreted using ab initio quantum molecular dynamics simulations. This diagnostic was used to shed new light on the non-equilibrium physics involved in various materials. This paper will focus on results devoted to the non-equilibrium dynamics of a copper foil brought from solid to warm dense matter regime, by the use of a femtosecond laser pulse. Particular emphasis will be given to the recent study of the ultrafast electronic transport, which was revealed by the femtosecond time resolution.