Two-dimensional gas

A two-dimensional gas is a collection of objects constrained to move in a planar or other two-dimensional space in a gaseous state. The objects can be: classical ideal gas elements such as rigid disks undergoing elastic collisions; elementary particles, or any ensemble of individual objects in physics which obeys laws of motion without binding interactions. The concept of a two-dimensional gas is used either because:

{{citation|surname1=Thomas Waldmann|surname2=Jens Klein|surname3=Harry E. Hoster|surname4=R. Jürgen Behm|periodical=ChemPhysChem|title=Stabilization of Large Adsorbates by Rotational Entropy: A Time-Resolved Variable-Temperature STM Study |volume=14|pages=162–169|date= 2012|issue=1|language=de|doi=10.1002/cphc.201200531|pmid=23047526|s2cid=36848079 }} followed by a 2D solid. It was shown that the transition from a 2D gas to a 2D solid state can be controlled by a scanning tunneling microscope which can affect the local density of molecules via an electric field.{{Cite journal|last1=Matvija|first1=Peter|last2=Rozbořil|first2=Filip|last3=Sobotík|first3=Pavel|last4=Ošťádal|first4=Ivan|last5=Pieczyrak|first5=Barbara|last6=Jurczyszyn|first6=Leszek|last7=Kocán|first7=Pavel|title=Electric-field-controlled phase transition in a 2D molecular layer|journal=Scientific Reports|volume=7|issue=1|pages=7357|doi=10.1038/s41598-017-07277-7|pmid=28779091|bibcode=2017NatSR...7.7357M|year=2017|pmc=5544747}}