Editing Exciton (section)

==== 0D semiconductors ====
{{See also|Quantum dot#Quantum confinement in semiconductors}}
In [[nanoparticles]] which exhibit quantum confinement effects and hence behave as quantum dots (also called 0-dimensional semiconductors), excitonic radii are given by<ref>
{{cite journal |last1=Brus |first1=Louis |date=1986 |title=Electronic wave functions in semiconductor clusters: experiment and theory |journal=The Journal of Physical Chemistry |volume=90 |issue=12 |pages=2555–2560 |doi= 10.1021/j100403a003|publisher=ACS Publications}}
</ref><ref name="Edvinsson2018">
{{cite journal|last1=Edvinsson|first1=T.|title=Optical quantum confinement and photocatalytic properties in two-, one- and zero-dimensional nanostructures|journal=Royal Society Open Science|volume=5|issue=9|year=2018|pages=180387|issn=2054-5703|doi=10.1098/rsos.180387|pmid=30839677|doi-access=free|pmc=6170533|bibcode=2018RSOS....580387E}}</ref>
:<math>a_\text{X} = \frac{\varepsilon_r}{\mu/m_0}a_0</math>

where <math>\varepsilon_r</math> is the [[relative permittivity]], <math>\mu \equiv (m_e^*m_h^*)/(m_e^*+m_h^*)</math> is the reduced mass of the electron-hole system, <math>m_0</math> is the electron mass, and <math>a_0</math> is the [[Bohr radius]].
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THE FOLLOWING IS INCORRECT
:<math>a_\text{X} = \frac{\varepsilon_\infty}{\mu/m_0}a_0</math>

where <math>\varepsilon_\infty</math> is the [[Permittivity#Complex permittivity|high-frequency dielectric constant]], <math>m^*_e</math> is the effective electron mass, <math>m_e</math> is the electron mass, and <math>a_0</math> is the [[Bohr radius]].
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