Physics:Quantum atoms/spin isomers of hydrogen - Revision history

WikiHarold: Clean Quantum page image and red links

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	~~<!-- No lead image available~~ in ~~existing page~~. ~~-->~~		[[File:Quantum_atoms_spin_isomers_of_hydrogen_concept_map.svg\|thumb\|280px\|spin isomers of hydrogen in the Quantum Collection.]]
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WikiHarold: Expand short Quantum intro

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	<div style="flex:1; line-height:1.45; color:#006b45; column-count:2; column-gap:32px; column-rule:1px solid #b8d8c8;">		<div style="flex:1; line-height:1.45; color:#006b45; column-count:2; column-gap:32px; column-rule:1px solid #b8d8c8;">
	'''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.<ref>{{Cite book \|last=Atkins \|first=Peter \|last2=de Paula \|first2=Julio \|title=Atkins' Physical Chemistry \|edition=8th \|publisher=W. H. Freeman \|year=2006 \|pages=451-452 \|isbn=0-7167-8759-8}}</ref>		'''spin isomers of hydrogen''' is a Book II topic in the Quantum Collection. '''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.<ref>{{Cite book \|last=Atkins \|first=Peter \|last2=de Paula \|first2=Julio \|title=Atkins' Physical Chemistry \|edition=8th \|publisher=W. H. Freeman \|year=2006 \|pages=451-452 \|isbn=0-7167-8759-8}}</ref> The distinction is quantum mechanical because the nuclear spin wavefunction must combine with the rotational state to satisfy exchange symmetry. Ortho and para hydrogen have different allowed rotational levels, thermal populations, and low-temperature properties. Spin-isomer conversion matters in cryogenics, molecular spectroscopy, hydrogen storage, and precision studies of simple molecules.
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	'''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.		'''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.<ref>{{Cite book \|last=Atkins \|first=Peter \|last2=de Paula \|first2=Julio \|title=Atkins' Physical Chemistry \|edition=8th \|publisher=W. H. Freeman \|year=2006 \|pages=451-452 \|isbn=0-7167-8759-8}}</ref>
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	== Quantum significance ==		== Quantum significance ==
	The ortho and para forms have different rotational energy level populations and different low-temperature behavior. At room temperature hydrogen is mostly orthohydrogen, while at very low temperature the para form is energetically favored.		The ortho and para forms have different rotational energy level populations and different low-temperature behavior. At room temperature hydrogen is mostly orthohydrogen, while at very low temperature the para form is energetically favored.<ref>{{Cite journal \|last=Matthews \|first=M. J. \|last2=Petitpas \|first2=G. \|last3=Aceves \|first3=S. M. \|title=A study of spin isomer conversion kinetics in supercritical fluid hydrogen for cryogenic fuel storage technologies \|journal=Applied Physics Letters \|year=2011 \|volume=99 \|issue=8 \|page=081906 \|doi=10.1063/1.3628453}}</ref>

	Spin isomers are important in cryogenics, molecular spectroscopy, nuclear spin physics, and precision studies of hydrogen molecules.		Spin isomers are important in cryogenics, molecular spectroscopy, nuclear spin physics, and precision studies of hydrogen molecules.
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	== References ==		== References ==
	{{reflist\|3}}		{{reflist\|3}}
	* {{Cite book \|last=Atkins \|first=Peter \|last2=de Paula \|first2=Julio \|title=Atkins' Physical Chemistry \|edition=8th \|publisher=W. H. Freeman \|year=2006 \|pages=451-452 \|isbn=0-7167-8759-8}}
	* {{Cite journal \|last=Matthews \|first=M. J. \|last2=Petitpas \|first2=G. \|last3=Aceves \|first3=S. M. \|title=A study of spin isomer conversion kinetics in supercritical fluid hydrogen for cryogenic fuel storage technologies \|journal=Applied Physics Letters \|year=2011 \|volume=99 \|issue=8 \|page=081906 \|doi=10.1063/1.3628453}}
	* {{Cite journal \|last=Chen \|first=Judy Y.-C. \|last2=Li \|first2=Yongjun \|last3=Frunzi \|first3=Michael \|last4=Lei \|first4=Xuegong \|last5=Murata \|first5=Yasujiro \|last6=Lawler \|first6=Ronald G. \|last7=Turro \|first7=Nicholas J. \|title=Nuclear spin isomers of guest molecules in H2@C60, H2O@C60 and other endofullerenes \|journal=Philosophical Transactions of the Royal Society A \|year=2013 \|volume=371 \|issue=1998 \|doi=10.1098/rsta.2011.0628 \|pmid=23918710}}
	* {{Cite journal \|last=Matsumoto \|first=Mitsuru \|last2=Espenson \|first2=James H. \|title=Kinetics of the Interconversion of Parahydrogen and Orthohydrogen Catalyzed by Paramagnetic Complex Ions \|journal=Journal of the American Chemical Society \|year=2005 \|volume=127 \|issue=32 \|pages=11447-11453 \|doi=10.1021/ja0524292 \|pmid=16089474}}

	{{Author\|Harold Foppele}}		{{Author\|Harold Foppele}}

WikiHarold: Replace Quantum references with Wikipedia-sourced references

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	== References ==		== References ==
	{{reflist\|3}}		{{reflist\|3}}
	* {{Cite ~~web~~ \|title=~~Ortho~~-~~hydrogen and para~~-hydrogen \|~~url~~=~~https:/~~/~~www~~.~~britannica~~.~~com/science/hydrogen/Ortho-hydrogen~~-and~~-para-hydrogen~~ \|~~website~~=~~Encyclopaedia Britannica~~ \|~~access-date~~=~~2026-05-23~~}}		* {{Cite book \|last=Atkins \|first=Peter \|last2=de Paula \|first2=Julio \|title=Atkins' Physical Chemistry \|edition=8th \|publisher=W. H. Freeman \|year=2006 \|pages=451-452 \|isbn=0-7167-8759-8}}
	* {{Cite ~~book~~ \|last=~~Silvera~~ \|first=~~Isaac F~~. \|title=~~The solid molecular hydrogens in~~ the ~~condensed phase: Fundamentals~~ and ~~static properties~~ \|journal=~~Reviews~~ of ~~Modern Physics~~ \|year=~~1980~~ \|volume=52 \|issue=2 \|pages=~~393~~-~~452~~ \|doi=10.~~1103~~/~~RevModPhys.52.393~~}}		* {{Cite journal \|last=Matthews \|first=M. J. \|last2=Petitpas \|first2=G. \|last3=Aceves \|first3=S. M. \|title=A study of spin isomer conversion kinetics in supercritical fluid hydrogen for cryogenic fuel storage technologies \|journal=Applied Physics Letters \|year=2011 \|volume=99 \|issue=8 \|page=081906 \|doi=10.1063/1.3628453}}
			* {{Cite journal \|last=Chen \|first=Judy Y.-C. \|last2=Li \|first2=Yongjun \|last3=Frunzi \|first3=Michael \|last4=Lei \|first4=Xuegong \|last5=Murata \|first5=Yasujiro \|last6=Lawler \|first6=Ronald G. \|last7=Turro \|first7=Nicholas J. \|title=Nuclear spin isomers of guest molecules in H2@C60, H2O@C60 and other endofullerenes \|journal=Philosophical Transactions of the Royal Society A \|year=2013 \|volume=371 \|issue=1998 \|doi=10.1098/rsta.2011.0628 \|pmid=23918710}}
			* {{Cite journal \|last=Matsumoto \|first=Mitsuru \|last2=Espenson \|first2=James H. \|title=Kinetics of the Interconversion of Parahydrogen and Orthohydrogen Catalyzed by Paramagnetic Complex Ions \|journal=Journal of the American Chemical Society \|year=2005 \|volume=127 \|issue=32 \|pages=11447-11453 \|doi=10.1021/ja0524292 \|pmid=16089474}}

	{{Author\|Harold Foppele}}		{{Author\|Harold Foppele}}

WikiHarold: Use Quantum See also index module

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Use Quantum See also index module

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	== See also ==		== See also ==
	* [[Physics:Quantum ~~atoms~~/~~hydrogen]]~~		{{#invoke:PhysicsQC\|tocHeadingAndList\|Physics:Quantum basics/See also/Matter}}
	* [[Physics:Quantum atoms/~~isotopes of hydrogen]]~~
	* [[Physics:Quantum Molecular orbital theory]]
	* nuclear spin states
	* [[Physics:Quantum fermion]]

	== References ==		== References ==

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	{{Short description\|Nuclear spin isomers of molecular hydrogen}}		{{Short description\|Nuclear spin isomers of molecular hydrogen}}
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	{{Short description\|Nuclear spin isomers of molecular hydrogen}}		{{Short description\|Nuclear spin isomers of molecular hydrogen}}
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	Spin isomers are important in cryogenics, molecular spectroscopy, nuclear spin physics, and precision studies of hydrogen molecules.		Spin isomers are important in cryogenics, molecular spectroscopy, nuclear spin physics, and precision studies of hydrogen molecules.

	== ~~Related pages~~ ==		== See also ==
	* [[Physics:Quantum atoms/hydrogen]]		* [[Physics:Quantum atoms/hydrogen]]
	* [[Physics:Quantum atoms/isotopes of hydrogen]]		* [[Physics:Quantum atoms/isotopes of hydrogen]]

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	{{Short description\|Nuclear spin isomers of molecular hydrogen}}		{{Short description\|Nuclear spin isomers of molecular hydrogen}}
	{{Quantum matter backlink\|Atoms}}		{{Quantum matter backlink\|Atoms}}
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	'''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.		'''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.
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	== Ortho and para hydrogen ==		== Ortho and para hydrogen ==

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	* [[Physics:Quantum atoms/isotopes of hydrogen]]		* [[Physics:Quantum atoms/isotopes of hydrogen]]
	* [[Physics:Quantum Molecular orbital theory]]		* [[Physics:Quantum Molecular orbital theory]]
	* ~~[[Physics:Quantum~~ spin]]		* nuclear spin states
	* [[Physics:Quantum fermion]]		* [[Physics:Quantum fermion]]

Maintenance script: Create Quantum Collection spin isomers of hydrogen page

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Create Quantum Collection spin isomers of hydrogen page

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{{Short description|Nuclear spin isomers of molecular hydrogen}}
{{Quantum matter backlink|Atoms}}

'''Spin isomers of hydrogen''' are forms of molecular hydrogen that differ in the relative nuclear spin orientation of the two protons in <math>\mathrm{H}_2</math>. The two main forms are '''orthohydrogen''' and '''parahydrogen'''.

== Ortho and para hydrogen ==
In '''orthohydrogen''', the two proton spins are parallel and the total nuclear spin is <math>I=1</math>. In '''parahydrogen''', the two proton spins are antiparallel and the total nuclear spin is <math>I=0</math>.

Because protons are fermions, the total molecular wavefunction must have the proper exchange symmetry. This links the nuclear spin state to the allowed rotational states of the molecule.

== Quantum significance ==
The ortho and para forms have different rotational energy level populations and different low-temperature behavior. At room temperature hydrogen is mostly orthohydrogen, while at very low temperature the para form is energetically favored.

Spin isomers are important in cryogenics, molecular spectroscopy, nuclear spin physics, and precision studies of hydrogen molecules.

== Related pages ==
* [[Physics:Quantum atoms/hydrogen]]
* [[Physics:Quantum atoms/isotopes of hydrogen]]
* [[Physics:Quantum Molecular orbital theory]]
* [[Physics:Quantum spin]]
* [[Physics:Quantum fermion]]

== References ==
{{reflist|3}}
* {{Cite web |title=Ortho-hydrogen and para-hydrogen |url=https://www.britannica.com/science/hydrogen/Ortho-hydrogen-and-para-hydrogen |website=Encyclopaedia Britannica |access-date=2026-05-23}}
* {{Cite book |last=Silvera |first=Isaac F. |title=The solid molecular hydrogens in the condensed phase: Fundamentals and static properties |journal=Reviews of Modern Physics |year=1980 |volume=52 |issue=2 |pages=393-452 |doi=10.1103/RevModPhys.52.393}}

{{Author|Harold Foppele}}