Discovery of Helium (Andrii Sofiienko)

Discovery of helium
Andrii Sofiienko
PhD, Senior Physicist
Visuray AS
28th of May, Bergen

Table of Contents
 What is “Helium”?
 Historical facts about Helium
 Chemical and physical properties of 4He
 Liquid Helium
 Spectroscopy of 4He
 Isotopes of Helium
 Astronomy and 4He
 Practical applications of 4He
 Deficit of 4He in the future?
 Escape of 4He into the space
28.05.2015 2

What is “Helium”?
Helium is a chemical element with symbol He
and atomic number 2. It is a colorless, inert,
monatomic gas that heads the noble gas group
in the periodic table [1].
28.05.2015 3
Fig. 1. The classical
representation of the
mulecula of 4He as a
nucleus with two
electrons on the orbit [2].

What is “Helium”?
28.05.2015 4
4
2
He

Historical facts about Helium
The first evidence of 4He was observed on August 18, 1868 as a
bright yellow line with a wavelength of 587.49 nm in the spectrum of
the chromosphere of the Sun. The line was detected by French
astronomer Jules Janssen during a total solar eclipse in Guntur,
India [3], [4]. This line was initially assumed to be sodium.
28.05.2015 5
Fig. 2. Emission spectra of He and Na. Jules Janssen
(1824 - 1907)
4He
23Na

On Oct. 20, 1868, English astronomer Norman Lockyer observed a
yellow line in the solar spectrum, which he named the D3
Fraunhofer line because it was near the known D1 and D2 lines of
sodium [5]. He concluded that it was caused by an element in the
Sun unknown on Earth. Lockyer and chemist Edward Frankland
named the element with the Greek word ἥλιος (helios) [6], [7].
28.05.2015 6
Norman Lockyer
(1836 - 1920)
Edward Frankland
(1825 - 1899)

In 1882, Italian physicist Luigi Palmieri detected 4He on
Earth, for the first time, through its D3 spectral line, when he
analysed the lava of Mount Vesuvius [8].
On March 26, 1895, Scottish chemist Sir William Ramsay
isolated 4He on Earth by treating the mineral cleveite (a variety
of uraninite) with mineral acids. He noticed a bright yellow line
that matched the D3 line observed in the spectrum of the Sun
[9-11].
4He was independently isolated from cleveite in 1895 by
chemists Per Teodor Cleve and Abraham Langlet in
Uppsala, Sweden, who collected enough of the gas to
accurately determine its atomic weight [4], [12], [13].
28.05.2015 7

In 1903, 4He gas (2%) was found in a natural gas field in
Dexter, Kansas. Helium of such concentration was found in a
number of other gas fields in the great plains in US.
In 1906, Hamilton P. Cady and David F. McFarland began to
analyze a large number of gas wells in Kansas, Oklahoma, and
Missouri. By the middle of 1906, they were able to report that
they had "a very unusual opportunity for obtaining helium
in practically unlimited quantities."
The USA is still the world’s largest supplier of helium, with many
reserves found in large natural gas fields (≈ 3·1010 m3).
28.05.2015 8

On 10 July 1908, Heike Kamerlingh Onnes (Nobel Prize in
Physics in 1978) was the first to liquefy 4He, using several
precooling stages and the Hampson-Linde cycle (Joule-Thomson
effect). He achieved the boiling point of 4He (−269 °C, 4.2 K). By
reducing the pressure of the liquid 4He he achieved a temperature
near 1.5 K [14].
28.05.2015 9
Heike Kamerlingh Onnes
(1853 - 1926)
Fig. 3. Paul Ehrenfest, Hendrik Lorentz and Niels
Bohr visit Heike Kamerlingh Onnes (1919) in the
cryogenic lab [15].

Heike Kamerlingh Onnes tried to
solidify 4He by further reducing the
temperature but failed because 4He
does not have a triple point
temperature at which the solid, liquid,
and gas phases are at equilibrium.
Onnes' student Willem Hendrik
Keesom was eventually able to
solidify 1 cm3 of 4He in 1926 by
applying additional external pressure
of 2.5 MPa [1], [14].
28.05.2015 10
Willem Hendrik Keesom
(1876 - 1956)

In 1938, Russian physicist Pyotr Leonidovich Kapitsa
discovered that 4He has almost no viscosity at T≈0K, a
phenomenon now called superfluidity [16]. This phenomenon is
related to Bose-Einstein condensation (Nobel Prize in Physics in
1978).
28.05.2015 11
Pyotr Leonidovich Kapitsa
(1894 - 1984)
He-II will "creep" along surfaces to find its own
level, after a short while, the levels in the two
containers will equalize. The helium film (called a
Rollin film) also covers the interior of the larger
container; if it were not sealed, the He-II would
creep out and escape.

In 1972, the same superfluidity phenomenon was observed in
3He, but at temperatures much closer to absolute zero, by
American physicists Douglas D. Osheroff, David M. Lee, and
Robert C. Richardson (they got Nobel Prize in Physics in 1996).
The phenomenon in 3He is thought to be related to pairing of 3He
fermions to make bosons, in analogy to Cooper pairs of electrons
producing superconductivity [17].
28.05.2015 12
Douglas D. Osheroff David M. Lee Robert C. Richardson
(1937 - 2013)

Chemical and physical properties of 4He
Property Value
Phase gas
Melting point 0.95 K (-272.2 °C) at 2.5 MPa
Boiling point 4.222 K (−268.928 °C)
Density
• Gas: 1.78·10-4 g/cc (20 °C);
• Liquid (m.p.): 0.145 g/cc;
• Liquid (b.p.): 0.125 g/cc;
Speed of sound
• Gas: 970 m/s;
• Liquid: 180 m/s.
Ionization energy 24.47 eV
Mass excess 28 MeV
Magnetic moment [μN] 0 (-2.1276 in 3He)
28.05.2015 13
Table. 1. Several main chemical and physical properties of 4He [1, 2, 18, 19].
He is a colourless, odourless, insipid and non-toxic gas. It’s less soluble in
water than any other gas. It’s the less reactive element and doesn’t essentially
form chemical compounds. The termic conductivity and the caloric content are
exceptionally high [18].

Liquid Helium
4He exists in a liquid form only at the extremely low
temperature of −268.928 °C (4.222 K).
Its boiling point and critical point depend on which isotope of
helium is present: the common isotope 4He or the rare isotope
3He. These are the only two stable isotopes of helium.
Table 2. Some physical properties of two isotopes of He [20].
28.05.2015 14
Properties of liquid helium 4He 3He
Critical temperature 5.2 K 3.3 K
Boiling point at one atmosphere 4.2 K 3.2 K
Minimum melting pressure 25 atm 29 atm at 0.3 K
Density 0.145 0.082
Superfluid transition temperature at
saturated vapor pressure
2.17 K
1 mK in the absence
of a magnetic field

Liquid Helium
Usually different isotopes of the same substance differ only in their
mass. However, the He isotopes behave very differently at low
temperatures. [21].
28.05.2015 15
Fig. 4. The phase diagram of 4He. The liquid
has a phase transition to a superfluid phase,
also known as He-II, at the temperature of
2.17K (at vapor pressure). The solid phase has
either hexagonal close packed (hcp) or body
centered cubic (bcc) symmetry.
Fig. 5. The phase diagram of 3He. There are two
superfluid phases of 3He, A and B. The line within
the solid phase indicates a transition between spin-
ordered and spin disordered structures (at low and
high temperatures, respectively).

Liquid Helium
The reason for the different behaviour of 4He and 3He is
quantum mechanics [21].
4He is a boson. The appearance of the superfluid phase in 4He
is related to Bose condensation, where a macroscopic fraction
of the atoms is in the lowest-energy one-particle state.
3He is a fermion (like electron) and it is forbidden by the Pauli
exclusion principle that more than one fermion is in the same
one-particle state. The superfluidity arises from formation of
weakly bound pairs of fermions, so called Cooper pairs. The
pairs behave as bosons. In the superfluid state there is a
macroscopic occupation of a single Cooper pair state.
28.05.2015 16

Spectroscopy of 4He
Electron configuration: 1s2
4He has unique emission lines and Fraunhofer lines –
discrete specra as usually in the gases [22].
28.05.2015 17

Spectroscopy of 4He
The absorption lines appear at precisely the same
wavelengths as the emission lines that would be produced
if the gas were heated to high temperatures [23].
28.05.2015 18

Spectroscopy of 4He and quantum mechanics
The Hamiltonian function of two electrons of 4He
(Werner Karl Heisenberg, 1926):
28.05.2015 19
120
2
20
2
2
2
2
10
2
2
1
2
44242
ˆ
r
e
r
Ze
mr
Ze
m
H



















x
y
z
e1e2 r12
r1r2
The last term represents electron-electron
repulsion at a distance r12.
)ˆ()ˆ(ˆ
iiiiii rErH  
)ˆ()ˆ()ˆ,ˆ( 221121 rrrr 
21 EEE 

i(ˆri,i,i)  Rni li
(ˆri)li mi
(i,i)
Rn,l is the radial part;
Yl,m is the spherical harmonic.

The solution for the discrete energy states is:
28.05.2015 20

En  
Zeff
2
e4
(40 )2
2 2
n2
Because the electrons are indistinguishable, the linear
combination of the wave functions also is a solution:

S 
1
2
( (ˆr1) (ˆr2)  (ˆr1) (ˆr2))
A 
1
2
( (ˆr1) (ˆr2)  (ˆr1) (ˆr2))
Symmetric
Asymmetric
  (ˆr1) (ˆr2)
Electrons in He can be in singlet state (asymmetric wave
function) or in triplet state (symmetric wave function).

Singlet states result when S=0.
 Para-helium (~ 25%)
Triplet states result when S=1
 Ortho-helium (~ 75%)
Triplet states are possible only
for the excided 4He due to the
Pauli exclusion principle.
Yellow line of 587.5 nm:
33D 23P
28.05.2015 21

Isotopes of Helium
There are 9 isotopes of Helium with different numbers of
neutrons), stable and unstable [24]:
28.05.2015 22
2He 3He 4He 5He 6He 7He 8He 9He 10He
Mass excess: 28 MeV in 4He and 14.93 MeV in 3He.

Astronomy and 4He
Hydrogen is the most abundant element in the known
Universe; helium is second.
The abundance of 4He (23% by mass) is well predicted by
the standard cosmological model, since they were
mostly produced shortly (~100 s) after the Big Bang, in a
process known as Big Bang nucleosynthesis.
There are two reasons of the 4He production:
 4He is stable and most neutrons combine with protons to form it
because the excess energy is also high – 28 MeV;
 Two 4He atoms cannot combine to form a stable atom: 8Be is
unstable.
28.05.2015 23

Astronomy and 4He
Solar Energy:
The Sun is by far the largest object in the solar system. It contains
more than 99.8% of the total mass. The Sun is, at present about
70% hydrogen and 28% helium by mass everything else ("metals")
amounts to less than 2% [34].
The Sun's power (about 386 billion billion MW) is produced by nuclear
fusion reactions. Each second about 700,000,000 tons of 1H are
converted to about 695,000,000 tons of helium (pp-cycle [35]):
28.05.2015 24
р + р → 2Н + е+ + νe (Eν < 0.42 MeV, τ ≈ 1010 y - weak interaction);
2Н + р → 3Не + γ + 5.49 MeV (τ ≈ 1.5 s);
3Не + 3Не → 4Не + 2р +12.86 MeV (65% - stellar core, τ ≈ 106 y);
3Не + 4Не → 7Ве + γ + 1.59 MeV (35% - stellar core, τ ≈5·105 y);
3Не + р → 4Не + νe + е+ + 18.77 MeV;

Practical applications of Helium
Today, He is used for many purposes that require some
of its unique properties [1], [2]:
 Cryogenics (32%)
 Pressurizing and purging (18%)
 Welding cover gas (13%)
 Controlled atmospheres (18%)
 Leak detection (4%)
 Breathing mixtures (2%)
 Other (13%, Neutron detection, zeppelins, …)
The balloons are perhaps the best known use of helium,
they are a minor part of all helium use.
28.05.2015 25

Practical applications of 3He, 4He
28.05.2015 26
The largest single use of
liquid 4He is to cool the
superconducting magnets
in modern MRI scanners [1].
Medical imaging:
Polarized 3He (it can be stored
for a long time) has recently
started to be used in magnetic
resonance tomography for
imaging the lungs by means of
nuclear magnetic resonance
[27].

Practical applications of 4He
A Helium Leak detector, also known as a Mass Spectrometer
Leak Detector (MSLD), is used to locate and measure the size of
leaks into or out of a system or containing device. The tracer gas,
helium, is introduced to a test part that is connected to the leak
detector. The 4He leaking through the test part enters through the
system and this partial pressure is measured and the results are
displayed on a meter [25].
28.05.2015 27

In rocket engines, 4He is often
used as a pressurizing agent,
pushing the liquid fuel and
oxidizer into the combustion
chamber [26].
4He is used for the purging of
the propellant feed systems
for liquid-hydrogen engines.
4He is used because its normal
boiling point is lower than that
of hydrogen. Other gases
would freeze, producing
particles that could clog
equipment [26].
28.05.2015 28

3He is a most important isotope in instrumentation for neutron
detection. It has a high absorption cross-section for thermal
neutrons. The neutrons are detected through the nuclear reaction
[27]
into charged particles tritium and protium that creates ionization in
the gas chamber.
28.05.2015 29
3 3 1
0.764n He H H MeV   
Application:
Control of illegal
transport of radioactive
materials (Uranium
and Plutonium)

A Zeppelin is a type of rigid airship named after Ferdinand
von Zeppelin who pioneered rigid airship development.
Zeppelin's ideas were first formulated in 1874 [28].
The Hindenburg was the largest airship ever built (97 people
on board, 1934). (It had been designed to use 4He, but the US refused to
allow its export. So, in what proved to be a fatal decision, the Hindenburg
was filled with flammable hydrogen – accident in May 1937, USA.)
28.05.2015 30
The first flight of LZ 1 over Lake Constance
(the Bodensee) in 1900Ferdinand von Zeppelin
(1838 - 1917)

Deficit of 4He in the future?
The diffusion speed of 4He through the solid materials is 3 times
more than of the air and by 65% more than of the hydrogen.
4He in the Earth's atmosphere escapes into space due to its
inertness and low mass. In a part of the upper atmosphere, 4He and
other lighter gases are the most abundant elements.
28.05.2015 31
In 1958 John Bardeen (the only person to
have won the Nobel Prize in Physics twice
[29]) and other influential scientists warned
the Congress that all our helium would be
gone by 1980. Congress reacted by spending
$1 billion on a separation plant in Amarillo,
Texas, and began stockpiling helium in empty
gas wells.
John Bardeen
(1908 - 1991)

Deficit of 4He in the future?
After 1980, still worldwide consumption of 4He has
increased by 5 to 10% a year in the past decade
The USGS Mineral Resources Program (MRP) reported
in 2012 that current global consumption of 4He is around
180 million m3/year [30], [31].
There’s something like 50 billion cubic metres lying
around out there [30], [31]. That’s a near 280 years
supply at current usage rates up to 2292.
28.05.2015 32

Escape of 4He into space
The atmosphere has a mass of about
5.15×1018 kg [30] three quarters of which is
within about 11 km from the surface.
28.05.2015 33
Composition of Earth's atmosphere by volume
is shown in right figure (1987 - 2009) [32].
∆Ratm ≈ 11 km
Vatm ≈ 5.6∙1018 m3
V4He ≈ 3∙1013 m3 (~10% of all 4He in Earth)
V3He ≈ 2∙108 m3 [27]
164 000 !He
He
production
V
years
dV
dt

 
 
 

The Earth’s atmosphere gradually leaks into space. The loss rate
is currently only about 3 kg/s for hydrogen and 50 g/s for 4He [33].
Nature income of 4He from the Earth’s crust is about 67 g/s [36].
Considering the density of 4He at normal conditions the annual
leakage is about 8.9 million m3/year – 20 times less that current
production rate!
It needs about 3.33 million years to lose all 4He just from the
atmosphere.
There are few reasons of the Helium escape:
 Molecular evaporation in the exosphere (h>500 km, T<3000 K);
 The upper atmosphere can absorb ultraviolet sunlight, warm up and
expand, pushing air upward. As the air rises, it accelerates smoothly
through the speed of sound and then attains the escape velocity. This form
of thermal escape is called hydrodynamic escape or the planetary wind.28.05.2015 34

Fig. 6. A schematic of the molecular evaporation of the gases from the
atmosphere [33].
28.05.2015 35

Fig. 7. A schematic of the atmosphere wind effect that leads to the leakage of
the gases [33].
28.05.2015 36

28.05.2015 37
EVIDENCE FOR
THERMAL ESCAPE
comes from considering
which planets and
satellites have
atmospheres and which
do not [33].
The deciding factor
appears to be the strength
of stellar heating (vertical
axis) relative to the
strength of a body’s
gravity (horizontal axis).
Airless worlds have strong
heating and weak gravity
(left of line). Bodies with
atmospheres have weak
heating and strong gravity
(right of line).

References
1. http://en.wikipedia.org/wiki/Helium
2. http://halo.wikia.com/wiki/Helium
3. Kochhar, R. K. (1991). "French astronomers in India during the 17th – 19th centuries".
Journal of the British Astronomical Association 101 (2): 95–100.
4. Emsley, John (2001). Nature's Building Blocks. Oxford: Oxford University Press. pp.
175–179.
5. Clifford A. Hampel (1968). The Encyclopedia of the Chemical Elements. New York:
Van Nostrand Reinhold. pp. 256–268.
6. Harper, Douglas. "helium". Online Etymology Dictionary.
7. Thomson, William (August 3, 1871). "Inaugural Address of Sir William Thomson".
Nature 4 (92): 261–278.
8. Stewart, Alfred Walter (2008). Recent Advances in Physical and Inorganic Chemistry.
BiblioBazaar, LLC. p. 201.
9. Ramsay, William (1895). "On a Gas Showing the Spectrum of Helium, the Reputed
Cause of D3, One of the Lines in the Coronal Spectrum. Preliminary Note".
Proceedings of the Royal Society of London 58 (347–352): 65–67.
10. Ramsay, William (1895). "Helium, a Gaseous Constituent of Certain Minerals. Part I".
Proceedings of the Royal Society of London 58 (347–352): 80–89.
11. Ramsay, William (1895). "Helium, a Gaseous Constituent of Certain Minerals. Part II--
". Proceedings of the Royal Society of London 59 (1): 325–330.
12. Langlet, N. A. (1895). "Das Atomgewicht des Heliums". Zeitschrift für anorganische
Chemie (in German) 10 (1): 289–292.
28.05.2015 38

References
13. Weaver, E.R. (1919). "Bibliography of Helium Literature". Industrial & Engineering
Chemistry.
14. https://en.wikipedia.org/wiki/Heike_Kamerlingh_Onnes
15. https://en.wikipedia.org/wiki/Museum_Boerhaave
16. Kapitza, P. (1938). "Viscosity of Liquid Helium below the λ-Point". Nature 141 (3558):
74.
17. Osheroff, D. D.; Richardson, R. C.; Lee, D. M. (1972). "Evidence for a New Phase of
Solid He3". Phys. Rev. Lett. 28 (14): 885–888.
18. http://www.lenntech.com/periodic/elements/he.htm
19. http://www.dpva.info/Guide/GuidePhysics/Sound/SoundSpeedTable1/
20. https://en.wikipedia.org/wiki/Liquid_helium
21. http://ltl.tkk.fi/research/theory/helium.html
22. http://www.stmary.ws/HighSchool/Physics/home/animations3/modernPhysics/Emissio
nAbsorptionSpectra.htm
23. http://www.bluffton.edu/~edmistonm/astronomy/AT404/HTML/AT40401.htm
24. http://en.wikipedia.org/wiki/Isotopes_of_helium
25. http://www.heliumleakdetection.net/Helium-Leak-Testing/what-is-helium-leak-
detection.html
28.05.2015 39

References
26. http://quantum-technology.com/about/helium.html
27. http://en.wikipedia.org/wiki/Helium-3
28. http://en.wikipedia.org/wiki/Zeppelin
29. http://en.wikipedia.org/wiki/John_Bardeen
30. http://www.forbes.com/sites/timworstall/2012/08/27/what-great-helium-shortage/
31. http://minerals.usgs.gov/minerals/pubs/commodity/helium/mcs-2012-heliu.pdf
32. http://en.wikipedia.org/wiki/Atmosphere_of_Earth
33. D.C. Catling, K.J. Zahnle, The Planetary Air Leak, Planetary science, May 2009.
34. Bhargav Boinpally, Solar Energy, California Takshila University, 2010.
35. http://en.wikipedia.org/wiki/Stellar_nucleosynthesis
36. Andrew S. Balian, The Unintended Disservice of Young Earth Science, Infinity, 2011.
28.05.2015 40

Thank you for your
attention!
28.05.2015 41

Discovery of Helium (Andrii Sofiienko)

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