Molecular Dynamics at Electrical- and Optical-Driven Phase Transitions: Time-Resolved Infrared Studies Using Fourier-Transform Spectrometers
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- 作者：Tobias Peterseim ; Martin Dressel
- 关键词：Fourier ; transform infrared spectroscopy ; Step ; scan technique ; Time ; dependent phenomena ; Vibrational spectroscopy ; Liquid crystals ; Photo ; induced phase transition ; Neutral ; ionic transition in TTF ; CA
- 刊名：Journal of Infrared, Millimeter, and Terahertz Waves
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：38
- 期：1
- 页码：104-123
- 全文大小：
- 刊物类别：Physics and Astronomy
- 刊物主题：Electrical Engineering; Electronics and Microelectronics, Instrumentation; Classical Electrodynamics;
- 出版者：Springer US
- ISSN：1866-6906
- 卷排序：38
文摘
The time-dependent optical properties of molecular systems are investigated by step-scan Fourier-transform spectroscopy in order to explore the dynamics at phase transitions and molecular orientation in the milli- and microsecond range. The electrical switching of liquid crystals traced by vibrational spectroscopy reveals a rotation of the molecules with a relaxation time of 2 ms. The photo-induced neutral-ionic transition in TTF-CA takes place by a suppression of the dimerization in the ionic phase and creation of neutral domains. The time-dependent infrared spectra, employed to investigate the domain-wall dynamics, depend on temperature and laser pulse intensity; the relaxation of the spectra follows a stretched-exponential decay with relaxation times in the microsecond range strongly dependent on temperature and laser intensity. We present all details of the experimental setups and thoroughly discuss the technical challenges.