@article {329,
	title = {Near-Field Stationary Sample Terahertz Spectroscopic Polarimetry for Biomolecular Structural Dynamics Determination},
	journal = {ACS Photonics},
	volume = {8},
	year = {2021},
	month = {02/2021},
	pages = {658-668},
	chapter = {658},
	abstract = {<p>THz polarimetry on environmentally sensitive and microscopic samples can provide unique insight into underlying mechanisms of complex phenomena. For example, near-field THz anisotropic absorption successfully isolated protein structural vibrations which are connected to biological function. However, to determine how these vibrations impact function requires high throughput measurements of these complex systems, which is challenged by the need for near field detection, sample environmental control and full polarization variation. Stationary sample anisotropic terahertz spectroscopy (SSATS) and near-field stationary sample anisotropic terahertz microscopy (SSATM) have been proposed using synchronous control of THz and electro optic probe polarizations along an iso-response curve. Here we realize these techniques through robust control and calibration of the THz and NIR polarization states. Both methods rapidly measure the linear dichroism in the far field and near field. Validation measurements using standard birefringent sucrose single crystals found the crystal orientation can be determined by scanning the reference polarization and the synchronous pump{\textendash}probe polarization settings can be optimized to eliminate artifacts. SSATM is then used to determine spectral reproducibility and dehydration effects for a series of chicken egg white lysozyme samples. Reproducible anisotropic absorbance bands are found at about 30, 44, 55, and 62 cm<sup>{\textendash}1</sup>. These bands initially sharpen with slow dehydration, similar to the increase in resolution achieved in X-ray crystallographic protein structure determination. The SSATM technique confirms the reliability of anisotropic absorption characterization of protein intramolecular vibrations and opens an avenue for rapid determination of how these long-range dynamics affect biological function.</p>},
	doi = {10.1021/acsphotonics.0c01876},
	url = {https://pubs.acs.org/doi/abs/10.1021/acsphotonics.0c01876},
	author = {Deng, Y. and McKinney, J. A. and George, D. K. and Niessen, K. A. and Sharma, A. and Markelz, A.G.}
}
@article {291,
	title = {Functional State Dependence of Picosecond Protein Dynamics},
	journal = {arXiv:1105.4425},
	year = {2012},
	url = {http://arxiv.org/0054394},
	author = {Chen, J. Y. and George, D. K. and He, Y. and Knab, J. R. and Markelz, A.G.}
}
@article {292,
	title = {Why is THz Sensitive to Protein Functional States? Oxidation State of Cytochrome C},
	journal = {Terahertz Science and Technology},
	volume = {3},
	year = {2010},
	chapter = {149-162},
	abstract = {<p>We investigate the presence of structural collective motions on a picosecond time scale for the heme protein, cytochrome c, as a function of oxidation and hydration, using terahertz (THz) time-domain spectroscopy and molecular dynamics simulations. Structural collective mode frequencies have been calculated to lie in this frequency range, and the density of states can be considered a measure of flexibility. A dramatic increase in the THz response occurs with oxidation, with the largest increase for lowest hydrations and highest frequencies. For both oxidation states the measured THz response rapidly increases with hydration saturating above ~25\% (g H<sub>2</sub>O/g protein), in contrast to the rapid turn-on in dynamics observed at this hydration level for other proteins. Quasi-harmonic collective vibrational modes and dipole-dipole correlation functions are calculated from the molecular dynamics trajectories. The collective mode density of states alone reproduces the measured hydration dependence providing strong evidence of the existence of these collective motions. The large oxidation dependence is reproduced only by the dipole-dipole correlation function, indicating the contrast arises from diffusive motions consistent with structural changes occurring in the vicinity of a buried internal water molecule.</p>},
	doi = {10.11906/TST.149-162.2010.12.15},
	url = {http://www.tstnetwork.org/10.11906/TST.149-162.2010.12.15/},
	author = {He,Y. and Chen, J.-Y. and Knab, J. R. and Zheng, W. and Markelz, A.G.}
}
@proceedings {317,
	title = {Third harmonic generation in a GaAs/AlGaAs Superlattice in the Bloch Oscillator Regime},
	year = {1995},
	month = {07/1995},
	pages = {161-163},
	address = {Chicago, IL},
	author = {Wanke, M. C. and Markelz, A.G. and Unterrainer, K. and Allen, S. J. and Bhatt, R.}
}
@proceedings {319,
	title = {Far-infrared harmonic generation from semiconductor heterostructures},
	volume = {1854},
	year = {1994},
	pages = {48-55},
	author = {Markelz, A.G. and Gwinn, E. G. and Sherwin, M. S. and Heyman, J. N. and Nguyen, C. and Kroemer, H.}
}
@proceedings {318,
	title = {Frequency Dependence of the Third Order Susceptibility of InAs Quantum Wells at Terahertz Frequencies},
	year = {1994},
	month = {08/1994},
	pages = {1193-1196},
	author = {Markelz, A.G. and Cerne, J. and Gwinn, E. G. and Brar, B. and Kroemer, H.}
}
@proceedings {320,
	title = {Far-infrared nonlinear response of electrons in semiconductor nanostructures},
	volume = {1854},
	year = {1993},
	pages = {36-47},
	author = {Sherwin, M. S. and Asmar, N. G. and Bewley, W. W. and Craig, K. and Felix, C. L. and Galdrikian, B. and Gwinn, E. G. and Markelz, A.G. and Gossard, A. C. and Hopkins, P. F. and Sundaram, M. and Birnir, B.}
}
@proceedings {321,
	title = {Conversion of 124 and 123 + cupric oxide:  microstructure and phase diagram},
	volume = {169},
	year = {1990},
	pages = {245-248},
	author = {Morris, D. E. and Nickel, J. H. and Markelz, A.G. and Gronksy, R. and Fendorf, M. and Burmester, C. P.}
}
