University of Illinois Urbana-Champaign

Exploring the solid state phase transition in DL-norvaline with terahertz spectroscopy

Schmuttenmaer, Charles A.

Content Files
1126690.pptx
3070.pdf

Permalink

https://hdl.handle.net/2142/100844

Description

Title
Exploring the solid state phase transition in DL-norvaline with terahertz spectroscopy
Author(s)
Schmuttenmaer, Charles A.
Contributor(s)
  • Williams, Michael R. C.
  • Regan, Kevin P.
  • Nemes, Coleen T.
  • Neu, Jens
Issue Date
2018-06-20
Keyword(s)
Mini-symposium: Far-Infrared Spectroscopy
Date of Ingest
  • 2018-08-17T16:09:53Z
  • 2018-12-12T22:35:09Z
Abstract
DL-Norvaline is a molecular crystal at room temperature and it undergoes a phase transition when cooled below 190 K. This phase transition is believed to be Martensitic. We investigate this phase transition by measuring its terahertz (THz) spectrum over a range of temperatures. Temperature-dependent THz time-domain spectroscopy (THz-TDS) measurements reveal that the transition temperature (Tβ→α) is 190 K. The influence of nucleation seeds was analyzed by determining the Tβ→α of molecular crystals with varying grain size. Grains of 5 µm or less result in a lower transition temperature (Tβ→α = 180 K) compared to larger grains of 125–250 µm (Tβ→α = 190 K). Additionally, we gain insight into the physical process of the phase transition via temperature-dependent THz-TDS spectra of doped and mixed molecular crystals. The addition of molecular dopants, which differ from DL-norvaline only at the end of the side chain which resides in the hydrophobic layers of the crystal, decreases Tβ→α. This is consistent with a solid-solid phase transition in which the unit cell shifts along this hydrophobic layer, and it leads us to believe that the phase transition in DL-norvaline is Martensitic in nature.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Permalink
http://hdl.handle.net/2142/100844
DOI
10.15278/isms.2018.WI05
Copyright and License Information
Copyright 2018 Charles A. Schmuttenmaer

Owning Collections

Abstracts & Presentations - 2018 International Symposium on Molecular Spectroscopy PRIMARY