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Archivio digitale delle tesi discusse presso l’Università di Pisa

Tesi etd-05102005-112503


Tipo di tesi
Tesi di laurea specialistica
Autore
Marianelli, Prisca
Indirizzo email
prisca@davide.it
URN
etd-05102005-112503
Titolo
Optical measurements of strong anchoring energies in nematic liquid crystals
Dipartimento
SCIENZE MATEMATICHE, FISICHE E NATURALI
Corso di studi
FISICA APPLICATA
Relatori
relatore Prof. Faetti, Sandro
Parole chiave
  • Nessuna parola chiave trovata
Data inizio appello
26/05/2005
Consultabilità
Completa
Riassunto
In this thesis we present some measurements of azimuthal anchoring energies for the nematic liquid crystal 5CB. The 5CB was in contact with glass surfaces covered with a thin polyimide substrate (Nissan corporation, SE-3510), that has been rubbed along a given direction. The glass surfaces were supplied by Stephane Joly of NEMOPTIC industry. Two different experimental methods -recently proposed by our group- have been used: a reflectometric method and a transmission method. Both these methods use a monocromatic laser beam (Laser He-Ne). In these subsrates we have measured a very high anchoring energy: Wa=3.5 10^(-4)J/m^2 (at T=25°C), corresponding to an extrapolation length de=12 nm.
We have studied how the anchoring energy depends from temperature and we descovered that it rapidly decreases near the clarification temperature. We have also observed the easy axis gliding, as the surfaces with weak anchoring energy.
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