Development of phonon-polarization THz spectroscopy, and the investigation of relaxor ferroelectrics

This thesis develops phonon-polariton based THz spectroscopy and uses this technique to make the first THz frequency dielectric measurements of a relaxor ferroelectric crystal, in particular KTao0.982Nb0.018O3 (KTN 1.8). THz spectroscopy has emerged as an important probe for a wide variety of systems with the development of pulsed THz radiation sources and time-domain detection methods. Four factors motivate the use of phonon-polaritons generated in an ionic crystal (typically LiNbO3 or LiTaO3) via impulsive stimulated Raman scattering as a THz source for spectroscopy: (1) the versatility of phonon-polariton waveform shaping and detection, (2) the ability to use the ionic crystal as a compact, integrated spectroscopic platform, (3) the high THz refractive index of the host material facilitates coupling of THz radiation into high-dielectric samples, and (4) the potential to generate large amplitude polariton fields for nonlinear THz spectroscopy. Here we demonstrate both reflection and transmission implementations of THz spectrometers based on grating interferometric measurement of the phase and amplitude of a phonon-polariton waveform before and after interaction with a sample.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Paxton, Benjamin John

Advisor dc:contributor.advisor

• Keith A. Nelson.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/36264

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/36264