Thermodynamikvorlesung von Prof. Dr. E. Schöll, PhD
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Der Artikel Das ideale Bosegas basiert auf der Vorlesungsmitschrift von Franz- Josef Schmitt des 5.Kapitels (Abschnitt 3) der Thermodynamikvorlesung von Prof. Dr. E. Schöll, PhD.
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{{#set:Urheber=Prof. Dr. E. Schöll, PhD|Inhaltstyp=Script|Kapitel=5|Abschnitt=3}}
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Rechnung geht analog zum Fermigas, nur dass die Besetzungszahlen Nj bis unendlich laufen können:
![{\displaystyle {\begin{aligned}&Y=\sum \limits _{{{N}_{1}}...{{N}_{l}}=0}^{\infty }{}\exp \left(-\beta \sum \limits _{j=1}^{l}{}\left({{N}_{j}}{{E}_{j}}-\mu {{N}_{j}}\right)\right)=\prod \limits _{j=1}^{l}{}\left(\sum \limits _{{{N}_{j}}=0}^{\infty }{}\exp \left(-\beta \left({{N}_{j}}{{E}_{j}}-\mu {{N}_{j}}\right)\right)\right)\\&=\prod \limits _{j=1}^{l}{}\left(\sum \limits _{{{N}_{j}}=0}^{\infty }{}{{t}_{j}}^{{N}_{j}}\right)\\&{{t}_{j}}:=\exp \left(-\beta \left({{E}_{j}}-\mu \right)\right)\\&Y=\prod \limits _{j=1}^{l}{}{\frac {1}{1-{{t}_{j}}}}=\prod \limits _{j=1}^{l}{}{{Y}_{j}}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5669fbde8a256e5ecc72453dd9278622c7838d7a)
Die geometrische Reihe konvergiert genau dann, wenn
, also wenn
à Bose - Einstein- Kondensation erfolgt bereits, wenn Ej=µ!
Somit ergibt sich die Wahrscheinlichkeit, die Besetzungszahlen N1, N2,.... der Einteilchenzustände E1, E2,.... zu finden:
![{\displaystyle {\begin{aligned}&P\left({{N}_{1}},{{N}_{2}},...\right)={{Y}^{-1}}\exp \left(-\beta \left({{N}_{j}}{{E}_{j}}-\mu {{N}_{j}}\right)\right)=\prod \limits _{j=1}^{l}{}\left(1-{{t}_{j}}\right){{t}_{j}}^{{N}_{j}}=\prod \limits _{j=1}^{l}{}p\left({{N}_{j}}\right)\\&(separiert)\\&\\&p\left({{N}_{j}}\right)=\left(1-{{t}_{j}}\right){{t}_{j}}^{{N}_{j}}=\left(1-\exp \left(\beta \left(\mu -{{E}_{j}}\right)\right)\right)\exp \left(-\beta \left({{N}_{j}}{{E}_{j}}-\mu {{N}_{j}}\right)\right)\\&1-\exp \left(\beta \left(\mu -{{E}_{j}}\right)\right):={{e}^{{\Psi }_{j}}}\\&p\left({{N}_{j}}\right)={{e}^{{\Psi }_{j}}}\exp \left(-\beta \left({{N}_{j}}{{E}_{j}}-\mu {{N}_{j}}\right)\right)\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/3955874ef81c2112ae5d9f6171d00e440f7e5281)
Mittlere Besetzungszahl im Zustand Ej:
![{\displaystyle {\begin{aligned}&\left\langle {{N}_{j}}\right\rangle ={\frac {\partial {{\Psi }_{j}}}{\partial \alpha }}={\frac {1}{\beta }}{\frac {\partial }{\partial \mu }}\ln {{Y}_{j}}=-{\frac {1}{\beta }}{\frac {\partial }{\partial \mu }}\ln \left(1-{{t}_{j}}\right)={\frac {{t}_{j}}{1-{{t}_{j}}}}={\frac {1}{{{t}_{j}}^{-1}-1}}\\&\left\langle {{N}_{j}}\right\rangle ={\frac {1}{\exp \left(\beta \left({{E}_{j}}-\mu \right)\right)-1}}={\frac {1}{\exp \left({\frac {\left({{E}_{j}}-\mu \right)}{kT}}\right)-1}}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ac9c72fa0297cecc9bdd3c9287f08d8180219fa9)
Die Bose- Verteilung folgt auch explizit aus
![{\displaystyle {\begin{aligned}&\left\langle {{N}_{j}}\right\rangle =\sum \limits _{{{N}_{j}}=0}^{\infty }{}{{N}_{j}}p({{N}_{j}})=\sum \limits _{{{N}_{j}}=0}^{\infty }{}{{N}_{j}}\left(1-{{t}_{j}}\right){{t}_{j}}^{{N}_{j}}=\left(1-{{t}_{j}}\right){{t}_{j}}{\frac {d}{d{{t}_{j}}}}\sum \limits _{{{N}_{j}}=0}^{\infty }{}{{t}_{j}}^{{N}_{j}}\\&=\left(1-{{t}_{j}}\right){{t}_{j}}{\frac {d}{d{{t}_{j}}}}\left({\frac {1}{1-{{t}_{j}}}}\right)=\left(1-{{t}_{j}}\right){{t}_{j}}\left({\frac {1}{{\left(1-{{t}_{j}}\right)}^{2}}}\right)={\frac {{t}_{j}}{\left(1-{{t}_{j}}\right)}}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c36ce0209e157b2037e8be2863554e49c6cddfaa)
Die Verteilung divergiert für Ej → µ. Das heißt: Die Zustandssumme Yj divergiert für Ej→µ
Vergleich aller drei Verteilungen:
![{\displaystyle \left\langle {{N}_{j}}\right\rangle ={\frac {1}{\exp \left({\frac {\left({{E}_{j}}-\mu \right)}{kT}}\right)-k}}\left\{{\begin{matrix}k=1\\k=0\\k=-1\\\end{matrix}}\right.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/6a047d26bd67d6f28df7dbbbbf7d30fb94016bf3)
mit k=-1 → Fermi - Dirac- Statistik
k=0 → Maxwell- Boltzmann
k= + 1 → Bose - Einstein!
Übergang zum Quasikontinuum der Zustände:
Fugazität:
![{\displaystyle {\begin{aligned}&\ln Y=\prod \limits _{j=1}^{l}{}\ln {{Y}_{j}}=-\sum \limits _{j}^{}{}\ln \left(1-\zeta {{e}^{-\beta {{E}_{j}}}}\right)\\&\approx -\left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\int _{0}^{\infty }{}dp{{p}^{2}}\ln \left(1-\zeta {{e}^{-\beta {\frac {{p}^{2}}{2m}}}}\right)\\&=-\left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\left[{\frac {{p}^{3}}{3}}\ln \left(1-\zeta {{e}^{-\beta {\frac {{p}^{2}}{2m}}}}\right)_{0}^{\infty }-\int _{0}^{\infty }{}dp{\frac {{p}^{3}}{3}}{\frac {\beta {\frac {p}{m}}\zeta {{e}^{-\beta {\frac {{p}^{2}}{2m}}}}}{\left(1-\zeta {{e}^{-\beta {\frac {{p}^{2}}{2m}}}}\right)}}\right]\\&{\frac {{p}^{3}}{3}}\ln \left(1-\zeta {{e}^{-\beta {\frac {{p}^{2}}{2m}}}}\right)_{0}^{\infty }=0\\&\Rightarrow \ln Y={\frac {2}{3}}\beta \left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\int _{0}^{\infty }{}dp{{p}^{2}}{\frac {\beta {\frac {{p}^{2}}{2m}}}{\left({\frac {1}{\zeta }}{{e}^{\beta {\frac {{p}^{2}}{2m}}}}-1\right)}}={\frac {2}{3}}\beta \left(2s+1\right){\frac {V}{{h}^{3}}}\int _{0}^{\infty }{}dp4\pi {{p}^{2}}\left\langle N(p)\right\rangle E(p)\\&\Rightarrow \ln Y={\frac {2}{3}}\beta \left(2s+1\right){\frac {V}{{h}^{3}}}\int _{0}^{\infty }{}dp4\pi {{p}^{2}}\left\langle N(p)\right\rangle E(p)={\frac {2}{3}}\beta U\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c1de0b87f2eaf7897df970512fd52d3fcc500e8e)
somit folgt:
![{\displaystyle pV=kT\ln Y={\frac {2}{3}}U}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c0cb5160e0c104ca9cc94e31d421e7c53a0dcf92)
also identisch zum fermigas! (S. 131)
(quasiklassischer, nicht entarteter Grenzfall)
Nebenbemerkung: Entartetetes Bosegas hoher Dichte kann nicht wie im Fermifall behandelt werden, da die Zustandssumme für Ej < µ divergiert!
Entwicklung nach Potenzen von
![{\displaystyle \xi ={{e}^{\frac {\mu }{kT}}}<<1}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2782b9154e9ed87b4b18806955cab639f4b66a9b)
also:
![{\displaystyle \mu <0}](https://wikimedia.org/api/rest_v1/media/math/render/svg/fa905b901e1874757c6f7bb0d1b243022920a965)
Gesamte Teilchenzahl:
![{\displaystyle {\begin{aligned}&{\bar {N}}=\sum \limits _{j}^{}{}\left\langle {{N}_{j}}\right\rangle \approx \left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\int _{0}^{\infty }{}dp{{p}^{2}}{\frac {1}{\exp \left({\frac {\left({{E}_{j}}-\mu \right)}{kT}}\right)-1}}=\left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\int _{0}^{\infty }{}dp{{p}^{2}}{\frac {1}{\exp \left({\frac {\left({\frac {{p}^{2}}{2m}}-\mu \right)}{kT}}\right)-1}}\\&{\frac {{p}^{2}}{2mkT}}=y\\&\Rightarrow {\bar {N}}=\sum \limits _{j}^{}{}\left\langle {{N}_{j}}\right\rangle \approx \left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\int _{0}^{\infty }{}dp{{p}^{2}}{\frac {1}{\exp \left({\frac {\left({\frac {{p}^{2}}{2m}}-\mu \right)}{kT}}\right)-1}}\\&={\frac {\left(2s+1\right)}{2}}{\frac {4\pi V}{{h}^{3}}}{{\left(2mkT\right)}^{\frac {3}{2}}}\int _{0}^{\infty }{}dy{\frac {{y}^{\frac {1}{2}}}{{{\xi }^{-1}}\exp \left(y\right)-1}}={\frac {\left(2s+1\right)}{2}}{\frac {4\pi V}{{h}^{3}}}{{\left(2mkT\right)}^{\frac {3}{2}}}\int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{\frac {\xi {{e}^{-y}}}{1-\xi {{e}^{-y}}}}\\&\int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{\frac {\xi {{e}^{-y}}}{1-\xi {{e}^{-y}}}}\approx \xi \int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{{e}^{-y}}+{{\xi }^{2}}\int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{{e}^{-2y}}+....\\&\int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{{e}^{-y}}={\frac {1}{2}}{\sqrt {\pi }}\\&\int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{{e}^{-2y}}={\frac {1}{{2}^{\frac {5}{2}}}}{\sqrt {\pi }}\\&\Rightarrow {\bar {N}}\approx {\frac {\left(2s+1\right)}{4}}{\frac {4V}{{h}^{3}}}{{\left(2\pi mkT\right)}^{\frac {3}{2}}}\left[\xi +{\frac {1}{{2}^{\frac {3}{2}}}}{{\xi }^{2}}\right]\\&\lambda :={{\left({\frac {{h}^{2}}{2\pi mkT}}\right)}^{\frac {1}{2}}}={{\left({\frac {2s+1}{{N}_{C}}}\right)}^{\frac {1}{3}}}\\&\Rightarrow {\bar {N}}\approx \left(2s+1\right){\frac {V}{{\lambda }^{3}}}\xi \left[1+{\frac {1}{{2}^{\frac {3}{2}}}}\xi \right]=\left(2s+1\right){\frac {V}{{\lambda }^{3}}}{{e}^{\frac {\mu }{kT}}}\left[1+{\frac {1}{{2}^{\frac {3}{2}}}}{{e}^{\frac {\mu }{kT}}}\right]\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/201de8933442840c6789fee3d8192bc47f19aa92)
Wobei wieder die thermische Wellenlänge eingesetzt wurde.
Auch hier:
![{\displaystyle \Delta {\bar {N}}=\left(2s+1\right){\frac {V}{{\lambda }^{3}}}{{e}^{\frac {\mu }{kT}}}{\frac {1}{{2}^{\frac {3}{2}}}}{{e}^{\frac {\mu }{kT}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/0bacf215acbff0030f443e4f3d36bff069029a51)
als Quantenkorrektur
Elimination von
durch
0. Näherung:
![{\displaystyle {\bar {N}}=\left(2s+1\right){\frac {V}{{\lambda }^{3}}}{{e}^{\frac {\mu }{kT}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5c9de91f39a4453c5b0a2942ba3940fc36edcb97)
1. Näherung:
![{\displaystyle {\begin{aligned}&{\bar {N}}=\left(2s+1\right){\frac {V}{{\lambda }^{3}}}{{e}^{\frac {\mu }{kT}}}\left[1+{\frac {1}{{2}^{\frac {3}{2}}}}{\frac {{\bar {N}}{{\lambda }^{3}}}{V\left(2s+1\right)}}\right]\\&\Rightarrow {{e}^{\frac {\mu }{kT}}}\approx {\frac {{\bar {N}}{{\lambda }^{3}}}{V\left(2s+1\right)}}\left[1-{\frac {1}{{2}^{\frac {3}{2}}}}{\frac {{\bar {N}}{{\lambda }^{3}}}{V\left(2s+1\right)}}\right]\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/729a9dd894fcfa740cc2cc6651d63ae1e78022de)
Innere Energie:
![{\displaystyle {\begin{aligned}&U=\left(2s+1\right){\frac {4\pi V}{{h}^{3}}}\int _{0}^{\infty }{}dp{{p}^{2}}{\frac {\frac {{p}^{2}}{2m}}{\exp \left({\frac {\left({\frac {{p}^{2}}{2m}}-\mu \right)}{kT}}\right)-1}}\\&{\frac {{p}^{2}}{2mkT}}=y\\&\Rightarrow U={\frac {\left(2s+1\right)}{2}}{\frac {4\pi V}{{h}^{3}}}{{\left(2mkT\right)}^{{\frac {3}{2}}kT}}\int _{0}^{\infty }{}dy{{y}^{\frac {3}{2}}}{\frac {\xi {{e}^{-y}}}{1-\xi {{e}^{-y}}}}\\&\int _{0}^{\infty }{}dy{{y}^{\frac {3}{2}}}{\frac {\xi {{e}^{-y}}}{1-\xi {{e}^{-y}}}}\approx \xi \int _{0}^{\infty }{}dy{{y}^{\frac {3}{2}}}{{e}^{-y}}+{{\xi }^{2}}\int _{0}^{\infty }{}dy{{y}^{\frac {1}{2}}}{{e}^{-2y}}+....\\&\int _{0}^{\infty }{}dy{{y}^{\frac {3}{2}}}{{e}^{-y}}={\frac {3}{4}}{\sqrt {\pi }}\\&\int _{0}^{\infty }{}dy{{y}^{\frac {3}{2}}}{{e}^{-2y}}={\frac {1}{{2}^{\frac {5}{2}}}}{\frac {3}{4}}{\sqrt {\pi }}\\&\Rightarrow U\approx {\frac {3}{2}}kTV{\frac {\left(2s+1\right)}{{h}^{3}}}{{\left(2\pi mkT\right)}^{\frac {3}{2}}}\left[\xi +{\frac {1}{{2}^{\frac {5}{2}}}}{{\xi }^{2}}\right]\\&\lambda :={{\left({\frac {{h}^{2}}{2\pi mkT}}\right)}^{\frac {1}{2}}}={{\left({\frac {2s+1}{{N}_{C}}}\right)}^{\frac {1}{3}}}\\&\Rightarrow U\approx {\frac {3}{2}}\left(2s+1\right){\frac {VkT}{{\lambda }^{3}}}\xi \left[1+{\frac {1}{{2}^{\frac {5}{2}}}}\xi \right]={\frac {3}{2}}\left(2s+1\right)kT{\frac {V}{{\lambda }^{3}}}{{e}^{\frac {\mu }{kT}}}\left[1+{\frac {1}{{2}^{\frac {5}{2}}}}{{e}^{\frac {\mu }{kT}}}\right]\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ac87d45f52e86b820bdd995e294ad7b810a5f7b6)
Also folgt als kalorische Zustandsgleichung:
![{\displaystyle {\begin{aligned}&U\approx {\frac {3}{2}}\left(2s+1\right){\frac {VkT}{{\lambda }^{3}}}\xi \left[1+{\frac {1}{{2}^{\frac {5}{2}}}}\xi \right]={\frac {3}{2}}\left(2s+1\right)kT{\frac {V}{{\lambda }^{3}}}{{e}^{\frac {\mu }{kT}}}\left[1+{\frac {1}{{2}^{\frac {5}{2}}}}{{e}^{\frac {\mu }{kT}}}\right]=\\&\\&\Rightarrow U\approx {\frac {3}{2}}kT{\bar {N}}\left[1-{\frac {1}{{2}^{\frac {5}{2}}}}{\frac {{\lambda }^{3}}{V\left(2s+1\right)}}{\bar {N}}\right]\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/7730d78ef4baf907d7a717ceff830361007e4904)
Mit der Quantenkorrektur
![{\displaystyle \Delta U\approx -{\frac {3}{2}}kT{\bar {N}}{\frac {1}{{2}^{\frac {5}{2}}}}{\frac {{\lambda }^{3}}{V\left(2s+1\right)}}{\bar {N}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/a6a57db47696d81d204fef694ec18bf6cfdb6d79)
thermische Zustandsgleichung
![{\displaystyle pV={\frac {2}{3}}U=kT{\bar {N}}\left[1-{\frac {1}{{2}^{\frac {5}{2}}}}{\frac {{\lambda }^{3}}{V\left(2s+1\right)}}{\bar {N}}\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/aea1e9e93e2cbb007e40067582d670aa1cccd723)
Hier wird der Druck um die Quantenkorrektur
![{\displaystyle \Delta pV=-kT{\bar {N}}{\frac {1}{{2}^{\frac {5}{2}}}}{\frac {{\lambda }^{3}}{V\left(2s+1\right)}}{\bar {N}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/beb4661b42e0ec2ea44d893781995c452cb46c87)
verringert.
Dies ist die sogenannte Bose- Anziehung! → Bildung von Bose - Einstein- Kondensaten!
Bose- Einstein- Kondensation[edit | edit source]
Grundzustand des Bosegases: Eo=0 (Verschiebung der Achse geeignet)
Somit:
![{\displaystyle {\begin{aligned}&\left\langle {{N}_{0}}\right\rangle ={\frac {1}{{{\xi }^{-1}}-1}}={\frac {\xi }{1-\xi }}\\&\xi ={{e}^{\beta \mu }}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5eee85bbe3f099f669e94c6eb5ae8ce9a3fe0c33)
Fugazität
Die mittlere Besetzungszahl dieses Quantenzustandes kann makroskopisch groß werden für
![{\displaystyle \left\langle {{N}_{0}}\right\rangle \approx {\bar {N}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/f8e432d05007d3e95d1fd5f993b126791f6653f4)
(alle Teilchen kondensieren im grundzustand)
Allgemein:
![{\displaystyle {\begin{aligned}&{\bar {N}}=\left\langle {{N}_{0}}\right\rangle +N{\acute {\ }}\\&N{\acute {\ }}=\sum \limits _{j>0}^{}{}\left\langle {{N}_{j}}\right\rangle \\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/6154317f4c8fcbbcf681f55fd5bc6ca43e63a3e8)
1) Normale Phase:
![{\displaystyle \xi ={{e}^{\beta \mu }}<<1}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b0d1916ce7e727559412ca33b22695b93e715ddb)
![{\displaystyle \left\langle {{N}_{0}}\right\rangle }](https://wikimedia.org/api/rest_v1/media/math/render/svg/3e05122d3f1162e76fa60a5b8796bccb26267e64)
ist vernachlässigbar! → verdünntes Bosegas, siehe oben, S. 140 ff.
2) kondensierte Phase
![{\displaystyle \xi \approx 1}](https://wikimedia.org/api/rest_v1/media/math/render/svg/93943e25d650446a2efdc161ffb58184ce37d192)
![{\displaystyle N{\acute {\ }}=\sum \limits _{j>0}^{}{}{\frac {1}{{{e}^{\beta {{E}_{j}}}}-1}}<<{\bar {N}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/9b18f027424921c0be669a2a255c3f01957f4c1f)
unabhängig von
!
Kontinuierlicher Fall:
![{\displaystyle {\frac {N{\acute {\ }}}{V}}\approx \left(2s+1\right){\frac {2\pi }{{h}^{3}}}{{\left(2mkT\right)}^{\frac {3}{2}}}\int _{0}^{\infty }{}dy{\frac {{y}^{\frac {1}{2}}}{{{e}^{y}}-1}}\approx \left(2s+1\right){{\left({\frac {2\pi mkT}{{h}^{2}}}\right)}^{\frac {3}{2}}}{\frac {2}{\sqrt {\pi }}}\int _{0}^{\infty }{}dy{{e}^{-y}}{{y}^{\frac {1}{2}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/edc92d4c28c9f6d73470f6d22fc8a7b65281b2d6)
Vergl. S. 141
![{\displaystyle {\begin{aligned}&{\frac {N{\acute {\ }}}{V}}\approx \left(2s+1\right){\frac {2\pi }{{h}^{3}}}{{\left(2mkT\right)}^{\frac {3}{2}}}\int _{0}^{\infty }{}dy{\frac {{y}^{\frac {1}{2}}}{{{e}^{y}}-1}}\approx \left(2s+1\right){{\left({\frac {2\pi mkT}{{h}^{2}}}\right)}^{\frac {3}{2}}}{\frac {2}{\sqrt {\pi }}}\int _{0}^{\infty }{}dy{{e}^{-y}}{{y}^{\frac {1}{2}}}\\&{\frac {2}{\sqrt {\pi }}}\int _{0}^{\infty }{}dy{{e}^{-y}}{{y}^{\frac {1}{2}}}=1\\&{{\left({\frac {2\pi mkT}{{h}^{2}}}\right)}^{\frac {3}{2}}}={{\lambda }^{-3}}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d25b8e14a3944638d94fd538081943c6cceac5ef)
Dabei ist dies der nicht kondensierte Anteil, eine normale Komponente, die sich wie verdünntes Bosegas verhält!
![{\displaystyle {\begin{aligned}&{\frac {N{\acute {\ }}}{V}}={\frac {\left(2s+1\right)}{{\lambda }^{3}}}{\tilde {\ }}{{T}^{\frac {3}{2}}}\\&\Rightarrow {\frac {N{\acute {\ }}}{\bar {N}}}={{\left({\frac {T}{{T}_{C}}}\right)}^{\frac {3}{2}}}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/27340552815b0725174b8470fd3bb566fcaf5efa)
{{#set:Definition=kritische Temperatur|Index=kritische Temperatur}}
Somit ergibt sich der Bruchteil der Kondensierten Teilchen:
![{\displaystyle {\begin{aligned}&{\frac {\left\langle {{N}_{0}}\right\rangle }{\bar {N}}}=1-{{\left({\frac {T}{{T}_{C}}}\right)}^{\frac {3}{2}}}\quad f{\ddot {u}}r\quad T<{{T}_{C}}\\&{\frac {\left\langle {{N}_{0}}\right\rangle }{\bar {N}}}=0\quad f{\ddot {u}}r\quad T>{{T}_{C}}\\\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/6d8b13c829a149337963df851edfefee793534a4)
Das markierte Gebiet ist das Gebiet der Bose- Einstein-Kondensation!
Bei zweikomponentigen Gasen liegt eine normale und ein kondensierte Komponente vor.
Dann wird der Druck nur durch die normale Komponente alleine bestimmt!
Vergleiche dazu auch: Dampfdruck über einer Flüssigkeit!
Phasenübegang bei
:
normale Phase - >Kondensierte Phase
Vorgang der Bose- Einstein- Kondensation
è ein makroskopisches Quantenphänomen!
Anwendung:
Die suprafluide Phase von
bei tiefen Temperaturen ähnelt einer 2- komponentigen Flüssigkeit aus normaler und kondensierter Komponente!