ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarAnders NilssonDepartment of Physics, Stockholm University, Sweden 
(host: Pusztai László)Accessing Waters “No-Mans Land” using X-ray 
LasersThursday, 12 June 2025, 10:00, KFKI Campus, Bldg. 1, 2nd floor, 
Conference RoomWater is of extreme importance for our society and the key 
component of life as we know it but it is also of extraordinary interest due 
to its remarkable physical properties that differ from almost all other 
liquids. Deviation of water’s properties from a simple liquid exists already 
in the ambient temperature regime and then becomes strongly enhanced upon 
supercooling. In particular, the finding that the thermodynamic response and 
correlation functions appear to diverge towards a singular temperature 
estimated by power-law fits of about 228 K has led to several hypotheses 
about the origin of waters anomalous properties. One hypothesis to explain 
the apparent divergence is that there exists a liquid-liquid transition with 
a liquid-liquid critical point at rather high positive pressures. In this 
scenario the Widom line, defined as the locus of correlation length maxima in 
the P-T plane, emanates from the critical point as a continuation of the 
liquid-liquid transition line into the one-phase region and the divergence in 
the response functions is towards this line. The challenge is that the 
temperature Ts lies below the homogeneous ice nucleation temperature 232 K, a 
region of the phase diagram that has been denoted as “no man’s land”, since 
ice crystallization occurs on much faster time scale compared to the 
experimentally accessible time scale in a typical laboratory setting.Here I 
will present how x-rays from x-ray lasers and synchrotron radiation sources 
have been used to probe the liquid phase of water from hot to the deep 
supercooled water regime inside no-man’s land. In particular, I will discuss 
if a liquid-liquid transition, Widom line, a critical point and a dynamical 
transition exists in deep supercooled water causing fluctuations all the way 
up to ambient temperature. This would open-up for that water at ambient 
conditions is in a supercritical state.   Minden érdeklődőt szívesen 
látunk! - Everyone is welcome to attend.Attila Nagysem-admin AT szfki.hu