ISIS Neutron and Muon Source Data Journal

This is a page describing data taken during an experiment at the ISIS Neutron and Muon Source. Information about the ISIS Neutron and Muon Source can be found at https://www.isis.stfc.ac.uk.

ISIS Neutron and Muon Source

ISIS Neutron and Muon Data

Determining the location of the low temperature termination of the Frenkel line on the phase diagram

Data collected on the
SANDALS instrument
at the ISIS facility

Abstract: A remarkable and unexpected feature about the Frenkel line as proposed in 2012 is the fact that it demarcates regions on the phase diagram where some fluid properties exhibit liquid-like versus gas-like behaviour, yet does not pass through the critical point. Instead it was proposed to cross the critical temperature at (roughly) 3x the critical density then trend to lower density upon temperature decrease and intersect the vapour pressure curve at 0.75 ? 0.8Tc. Whilst experimental works have focussed on the supercritical region, the theoretical proposal that the Frenkel line intersects the vapour pressure curve at 0.75 ? 0.8Tc has been challenged by an alternate proposal (from classical molecular dynamics simulations, using nitrogen as an example) that it continues to the vicinity of the triple point. Here, we are therefore making the case for an experiment on subcritical fluid nitrogen at 90 K (0.71Tc) to discover in what region of the Pressure-temperature (P,T) phase diagram the low P,T termination of the Frenkel line lies.

Public release date: 20 October 2026

Experimenter: Dr Ciprian Pruteanu
Local Contact: Dr Oliver Alderman
Experimenter: Mr Luke Jones
Experimenter: Dr John Proctor
Experimenter: Professor Graeme Ackland
Experimenter: Mr Tianrui Wang
Experimenter: Dr John Loveday
Experimenter: Miss Cerian Robertson

DOI: 10.5286/ISIS.E.RB2310196-2

Parent DOI: 10.5286/ISIS.E.RB2310196

ISIS Experiment Number: RB2310196

Part Number: 2

This dataset is NOT yet publicly available.
The release date is: 20 October 2026

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the dataset

Date of Experiment: 17 October 2023

Publisher: STFC ISIS Neutron and Muon Source

Data format: RAW/Nexus
Select the data format above to find out more about it.

Data Citation

The recommended format for citing this dataset in a research publication is as:
[author], [date], [title], [publisher], [doi]

For Example:
Dr Ciprian Pruteanu et al; (2023): Determining the location of the low temperature termination of the Frenkel line on the phase diagram, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2310196-2

Data is released under the CC-BY-4.0 license.