Creating nano-size ultra-cold labs

Hydrogen is typically impossible to study in liquid form—it becomes a solid at -259°C (-434°F). But by confining small clusters of hydrogen molecules inside helium nanodroplets at -272.25°C (0.4 K), Dr. Momose and colleagues at RIKEN and Kanazawa University in Japan were able to keep the hydrogen in liquid form even at low temperatures.

Then the team embedded a methane molecule in the hydrogen cluster and set it spinning with laser pulses. The spinning methane molecule acts like a canary in a coal mine for superfluidity—if it rotates faster without resistance, the surrounding hydrogen was superfluid. When enough hydrogen molecules (15 to 20 molecules) were placed in a cluster, the methane rotated without resistance, indicating the hydrogen was acting as a superfluid.

"We were thrilled when we first observed the strikingly clear methane spectrum in a tiny droplet of liquid hydrogen,” said Dr. Hatsuki Otani, who conducted the work while a PhD student in chemistry at UBC. “It was a strong sign of hydrogen’s superfluidity. Then theoretical results from colleagues at Kanazawa University matched our experimental data perfectly."

Toward frictionless clean energy

Hydrogen is used in fuel cells, which only release water as a byproduct—but production, storage and transportation challenges has limited infrastructure advances for the clean fuel. The frictionless flow of superfluid hydrogen could inspire new technologies for more efficient hydrogen transportation and storage in the future.