Physics and Astronomy Colloquium Series
Physics Majors' Senior Project Talks
Thursday, Dec. 11, 2014
"Paranematic Ordering Induced by Polymer Fibrils in the Isotropic Phase of Nematic 5CB Liquid Crystals"
We use transmission ellipsometry to measure the polar anchoring coefficient W of nematic 4-Cyano-4'-pentylbiphenyl (5CB) liquid crystals to an alignment layer made of RM-82 photo-polymer (Merck), and find that strong anchoring is present. By introducing a polymer network of 3-5% concentration RM-82 to the liquid crystal bulk, we find that order is maintained for temperatures greater than the nematic-isotropic transitioin temperature of 5CB. A model based on the Landau-deGennes theory is used to describe the optical retardation due to the anchoring behavior of liquid crystal molecules to polymer fibrils in the isotropic phase. By parametrically fitting the model to our experimental data, we obtain values for fibril radius r0, fibril half-separation distance R0, and the characteristic nematic correlation length ξ0 of the system. We investigate the dependence of these parameters on polymer concentration for 3,4, and 5% RM-82.
"Sacramento State SRT"
An attempt was made to identify the mechanical and electrical problems preventing Sacramento State University's Small Radio Telescope from functioning. The telescope's mount has been rewired and now works. The telescope's feed, low-noise amplifier, and receiver have all been replaced.
The Physics and Astronomy Colloquium Series is open to all members of the university. Unless otherwise noted, talks are held on Thursday afternoons at 4:00-5:20 in Mendocino 1015. Schedule is regularly updated as dates, titles, and abstracts are received. Please check back often. To receive updates about the Colloquium Series, please join our Events Mailing List. For past semesters' series, see our archive.
Fall 2014 Semester Schedule
We will update the schedule for the Fall 2014 semester as we get closer to the start of the semester. Have a great summer!
Oct. 2, 2014
Oct. 16, 2014
Oct. 30, 2014
Nov. 13, 2014
Dec. 4, 2014
Dec. 11, 2014