Laser-based circular dichroism detection of molecules in flowing liquid systems using high frequency polarization modulation

1987 ◽  
Author(s):  
Robert E. Synovec ◽  
Edward S. Yeung
Keyword(s):  
Circular Dichroism ◽  
High Frequency ◽  
Polarization Modulation ◽  
Flowing Liquid ◽  
Liquid Systems ◽  
Circular Dichroïsm

Polarization Modulation Fourier Transform Infrared Spectroscopy with Digital Signal Processing: Comparison of Vibrational Circular Dichroism Methods

2001 ◽  
Vol 55 (11) ◽  
pp. 1435-1447 ◽  
Author(s):  
Jovencio Hilario ◽  
David Drapcho ◽  
Raul Curbelo ◽  
Timothy A. Keiderling
Keyword(s):  
Signal Processing ◽  
Circular Dichroism ◽  
Digital Signal Processing ◽  
Digital Signal ◽  
Vibrational Circular Dichroism ◽  
Polarization Modulation ◽  
Rapid Scan ◽  
Ft Ir ◽  
Lock In ◽  
Circular Dichroïsm

Digital signal processing (DSP) has been implemented in a step-scan FT-IR spectrometer in a modification that enables processing of high-frequency polarization modulation signals. In this work, direct comparison is made between vibrational circular dichroism (VCD) spectra measured on the same instrument, with the same samples, under the same conditions, using this new DSP method and a conventional rapid-scan technique (employing a lock-in amplifier for demodulation). In this initial test, both techniques generated high-quality VCD for solution phase, rigid chiral molecules such α-pinene and camphor. Noise and reproducibility of known spectral features, as well as enhancing signal measurability and discrimination, were used as criteria for the selection of optimal DSP measurement parameters. Both DSP and rapid-scan VCD methods produced qualitatively reasonable spectra for biologically related molecules such as poly-γ-benzyl-L-glutamate, poly-L-proline, and duplex RNA homopolymer. In most cases, the DSP method had a slight signal-to-noise advantage based on standard deviations of the noise trace data over the rapid-scan measurement, but the final results did depend on the details of the data collection and the phase correction methods inherent in both methods.

Solid State Circular Dichroism Spectra Obtained by Phase Modulation Spectroscopy Exemplified by the Tris(Ethylenediamine)chromium(III) Chromophore

1980 ◽  
Vol 34 (3) ◽  
pp. 360-363 ◽  
Author(s):  
Hans Peter Jensen
Keyword(s):  
Group Theory ◽  
Circular Dichroism ◽  
Solid State ◽  
Absorption Band ◽  
Phase Modulation ◽  
Polarization Modulation ◽  
Circular Dichroism Spectra ◽  
Modulation Spectroscopy ◽  
Circular Dichroïsm

This paper shows what a marvelous thing it is to be able to get a complete dichroic tensor for an absorption band, how useful this information is, and what elegant tools there are available to help one out; namely, polarization, modulation spectroscopy, and group theory.

scholarly journals Terahertz Circular Dichroism Spectroscopy of Biomaterials Enabled by Kirigami Polarization Modulators

2019 ◽  
Author(s):  
Won Jin Choi ◽  
Gong Cheng ◽  
Zhengyu Huang ◽  
Shuai Zhang ◽  
Theodore B. Norris ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Dynamic Range ◽  
Mechanical Strain ◽  
Thz Radiation ◽  
Polarization Modulation ◽  
Electromagnetic Spectrum ◽  
Polarization Rotation ◽  
Optical Elements ◽  
Out Of Plane ◽  
Circular Dichroïsm

ABSTRACTSTerahertz circular dichroism (TCD) offers spectroscopic capabilities for understanding mesoscale chiral architecture and low-energy vibrations of macromolecules in (bio)materials1–5. However, the lack of dynamic polarization modulators comparable to polarization optics for other parts of electromagnetic spectrum impedes proliferation of TCD spectroscopy6–10. Here we show that tunable optical elements fabricated from patterned plasmonic sheets with periodic kirigami cuts make possible polarization modulation of THz radiation under application of mechanical strain. A herringbone pattern of microscale metal stripes enables dynamic range of polarization rotation modulation exceeding 80° over thousands of cycles. Upon out-of-plane buckling, the plasmonic stripes function as reconfigurable semi-helices of variable pitch aligned along the THz propagation direction. Several biomaterials, exemplified by elytrons of Chrysina gloriosa beetles, revealed distinct TCD fingerprints associated with the helical substructure in the biocomposite. Analogous kirigami modulators will also enable other applications in THz optics, such as polarization-based terahertz imaging and phase-encrypted telecommunication.

Sign in / Sign up

Export Citation Format

Share Document