Physics World

Atomic hydrogen: the quantum gas

Jook T. M. Walraven

Published Jul 1, 1995• 5 citations

Abstract

It was a complete surprise when Isaac Silvera and his colleagues at the University of Amsterdam observed the existence of a remarkably stable gas of hydrogen atoms in 1979. They found that a gas of the so-called “atom of atoms” could be confined for several minutes in a cryogenic test cell close to absolute zero, provided that the walls were coated with a film of liquid helium. Until then, if researchers wanted to study monoatomic hydrogen for any length of time they had to use a discharge source to replace those hydrogen atoms that recombined to form molecular hydrogen. But most important, Silvera's experiments marked the first experimental investigation of a dilute quantum gas.

DOI: 10.1088/2058-7058/8/7/29

Related papers

A stabilised gas of atomic hydrogen

Isaac F. Silvera

We, at the Natuurkundig Laboratorium der Universiteit van Amsterdam, have recently succeeded in creating a gas of atomic hydrogen in a special long-lived state called spin polarised hydrogen, H↓ (see I F Silvera and J T M Walraven 1980 Phys. Rev. Lett. 44 164). Gases with densities up to almost 10 17 cm -3 can exist for periods of minutes up to hours depending on the conditions.

Physics BulletinNov 1, 19810 citations

THE STABILIZATION OF ATOMIC HYDROGEN : A NEW BOSE GAS

Isaac F. Silvera, Jook T. M. Walraven

Under normal circumstances a gas of atomic hydrogen (H) is highly unstable with respect to recombination to molecular hydrogen, H2. We have succeeded in stabilizing a gas of spin polarised hydrogen (H↓) at T = 300 mK in magnetic fields up to 10 Tesla in a superfluid helium coated cell. Densities of at least 1016atoms/cc have already been achieved. H is found to have a surprisingly long life even in zero magnetic field. Evidence points to H↓ remaining in the gaseous form and not liquifying or condensing out on the surfaces to any large extent. The crucial experimental techniques used to stabilize H↓ will be discussed as well as some of the observed properties and expectations of this new Bose gas.

Le Journal de Physique ColloquesJul 1, 19805 citations

Stable spin-polarized atomic hydrogen

Bertram M. Schwarzschild

The strong attraction between hydrogen atoms of opposite electron spin would seem to make it impossible to have stable monatomic hydrogen gas, except in interstellar space. But the force between hydrogen atoms of parallel spin is predominantly repulsive. Isaac Silvera and Jook Walraven of the University of Amsterdam have taken advantage of the absence of bound states for spin-polarized hydrogen to produce a monatomic hydrogen gas that showed no sign of reverting to ordinary H2 after almost an hour in a high magnetic field at low temperature, despite its very considerable density—more than 1016 atoms/cm3.

Physics TodayJun 1, 19802 citations

H Gas: Captured at last?

Peter M. Bell

In the strange world of low‐temperature physics, few more unusual phenomena have been discovered than monatomic hydrogen gas. According to a recent report (New Scientist, Jan. 1981, p. 204), hydrogen atoms do not tend to pair up to form molecules under special low‐temperature‐cryogenic experimental conditions. The reasons for the existence of atomic hydrogen gas at ultra‐low temperature, and for its implications, lie in an understanding of its almost pure quantum mechanical properties. Practical uses of atomic hydrogen will await more knowledge of its properties, but right now, if available in sufficient abundance, atomic hydrogen could be used in maser clocks because it emits highly defined frequencies of microwave radiation at room temperature, and atomic hydrogen gas could be used as an energy conservative fuel, as it recombines to the diatomic molecule. For every recombination between two hydrogen atoms, 4.5 eV of energy are released, which calculates to be over 1 million watts of power per second for 10 grams of atomic hydrogen recombined. The large impulse relative to its light mass could be significant in applications of atomic hydrogen as a rocket fuel. Practical applications aside, the main interest in atomic hydrogen at this moment is in the insight into quantum mechanics that study of its properties may provide. Atomic hydrogen atoms ‘abound throughout the universe,’ even though not on Earth, and thus quantum effects in space, and the hydrogen‐rich planets as well, may be elucidated by results of these studies.

EosFeb 24, 19810 citations

Hydrogen: a quantum gas at last

Tom W. Hijmans

The experimental observation of Bose-Einstein condensation in gas of rubidium atoms in 1995 had huge impact on the physics community with reports of a new state of matter making newspaper headlines all over the world. By comparison, it was in relative obscurity that Simo Jaakkola and his group at the University of Turku in Finland, in collaboration with researchers at the Kurchatov Institute in Moscow, recently observed the two-dimensional analogue of the effect (A I Safonov et al. 1998 Phys. Rev. Lett. 81 4545). Jaakkola observed two-dimensional Bose-Einstein condensation (2D BEG) in gas of specially prepared hydrogen atoms adsorbed on the surface of liquid helium. In Bose-Einstein condensation all the particles in system collapse into single quantum state that has many unusual and novel properties.

Physics WorldFeb 1, 19992 citations

Stabilization of atomic hydrogen

А.Ф. Сильвера, Yu Valraven

The authors succeeded in conserving gas in monatomic state for several hours at the ultimately permissible temperature in a strong magnetic field. Under such conditions hydrogen atoms unite themselves relatively slowly, therefore gas may be considered as stable. As it follows from experimental results, monatomic hydrogen remains gaseous up to 0.08 K - the ultralow temperature at which the investigations have been carried out. These data at least preliminarily confirm an assumption that atomic hydrogen remains gaseous at absolute zero temperature, as it is predicted by the quantum theory.

Apr 1, 19830 citations