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Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures

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Persistent molecular superfluid response in doped para-hydrogen clusters.

P L Raston¹, W Jäger, H Li

¹Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.

Physical Review Letters

|September 26, 2012

Summary

Observing superfluidity in para-hydrogen (p-H(2)) is difficult. Using carbon monoxide as a probe molecule allows measurement of effective inertia while maintaining maximum superfluid response, unlike carbon dioxide.

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Area of Science:

Quantum fluid dynamics
Low-temperature physics
Molecular spectroscopy

Background:

Direct observation of superfluid response in para-hydrogen (p-H(2)) is challenging.
Previous studies using carbon dioxide as a probe showed reduced superfluid response due to localization in larger clusters.

Purpose of the Study:

To identify a probe molecule that can measure the effective inertia of para-hydrogen (p-H(2)) clusters without inducing localization.
To maintain maximum superfluid response during the measurement.

Main Methods:

Microwave spectroscopy was employed to probe the effective inertia of para-hydrogen clusters.
Theoretical analysis using Feynman path-integral simulations supported the experimental findings.

Main Results:

The lighter carbon monoxide molecule was found to be a suitable probe for measuring the effective inertia of para-hydrogen (p-H(2)) clusters.
Carbon monoxide allows for the measurement of effective inertia while preserving the maximum superfluid response.

Conclusions:

Carbon monoxide enables effective measurement of para-hydrogen superfluid response.
This finding overcomes the challenge of localization observed with heavier probe molecules.