@proceedings {544, title = {Stabilization of Terahertz Vibrational Modes in Illuminated Orange Carotenoid Protein Crystals}, year = {2020}, address = {Buffalo, NY}, abstract = {

Orange carotenoid protein (OCP) controls efficiency of the phycobilisome (PBS), the light harvesting antenna in cyanobacteria, to prevent oxidative damage. The OCP switches from resting state to photo protective state with intense blue light illumination. Questions persist as to why OCPR interaction increases with the PBS over that with the OCPO. Here we examine the role of long-range intramolecular vibrations within OCP. Using Stationary Sample Anisotropic Terahertz Microscopy (SSATM) we measure changes in the intramolecular vibrations with photo switching. We report the first observation of switching in the intramolecular vibrations with photoexcitation. Results suggest that there is a stiffening of the molecule in the photo protective state. This increase in structural stability may enhance the interaction with the PBS change in OCP interaction with PBS. In low light, carotenoid bound OCP appears orange (OCP o ) and is inactive. Illumination by strong light converts OCP to the active, red (OCPR) state, which interacts with the PBS. A comparison of anisotropic THz microscopy measurements of dark adapted (OCP o ) and illuminated OCP crystals indicate differences in their vibrational modes that may be important for OCP-PBS interactions.

}, doi = {10.1109/IRMMW-THz46771.2020.9370827}, author = {McKinney, J. and Sharma, A. and Deng, Y. and George, D. and Lechno-Yossef, S. and Kerfeld, C. and Markelz, A.} } @article {249, title = {Spectral Assignment of Lysozyme Collective Vibrations}, journal = {Biophysical Journal}, volume = {116}, number = {3}, year = {2019}, note = {ISI Document Delivery No.: HO2XG
Times Cited: 0
Cited Reference Count: 1
Cited References:
Niessen KA, 2017, BIOPHYS J, V112, P933, DOI 10.1016/j.bpj.2016.12.049
Deng, Yanting Mckinney, Jeffrey Romo, Tod Grossfield, Alan Markelz, Andrea
63rd Annual Meeting of the Biophysical-Society
Mar 02-06, 2019
Baltimore, MD
Biophys Soc

8
Cell press
Cambridge
1542-0086
1}, month = {Feb}, pages = {564A-564A}, type = {Meeting Abstract}, abstract = {
Global structural vibrations at terahertz (THz) frequencies have been associated with protein function and allosteric control. A chief obstacle to utilizing this control mechanism has been measurement of specific motions. Recently it was shown that while the vibrational density of states, and isotropic absorption spectra are broad and featureless, collective vibrations can be isolated based on their directionality using aligned samples (realized with protein crystals) and anisotropic THz microscopy [1]. However the assignment of resonant bands to specific structural motions was complicated by the high symmetry of the tetragonal crystals used, and the slow experimental method. To structurally map the vibrations of the chicken egg white lysozyme (CEWL) we measure anisotropic absorption of triclinic crystals using our new technique: ideal polarization varying anisotropic THz microscopy (IPV-ATM). The low symmetry triclinic crystals provide absolute protein orientation, and the near field IPV-ATM rapidly measures broadband terahertz linear dichroism of the microcrystals. All measurements were performed at room temperature under 100\% humidity conditions. The unit cell parameters of triclinic lysozyme nitrate crystals, α = 28.5A{\textdegree}, b = 32.7A{\textdegree}, c = 35.1A{\textdegree}, α = 88.2{\textdegree}, β = 108.9{\textdegree}, γ = 111.9{\textdegree}, belonging to the P1 space group, were determined by X-ray diffraction before and after THz measurements. The intramolecular vibrational absorbance of the triclinic crystals has a more complex polarization dependence than the higher symmetry tetragonal crystals, as expected. While the tetragonal crystals have two strong bands at 45cm-1 and 55cm-1, the triclinic crystals have a series of narrow bands between 40 and 60cm-1 and a prominent band at 30cm-1. We compare the measured spectra to normal mode ensemble averaged calculations to assign the observed resonances, and isolating which collective motions impact the catalytic site.
}, keywords = {Biophysics}, isbn = {0006-3495}, doi = {10.1016/j.bpj.2018.11.3032}, author = {Deng, Y. T. and McKinney, J. and Romo, T. and Grossfield, A. and Markelz, A.} } @proceedings {230, title = {Stationary Sample Anisotropic THz Spectroscopy using Discretely Tunable THz Sources}, year = {2019}, note = {Irmmw-thz
44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
Sep 01-06, 2019
Paris, FRANCE
Lytid; TYDEX; Swiss Terahertz; Fondat Maison Chimie; CNRS, Lab Physique ENS; Li2S; LUNA; MenloSystems; ENS; PSL Univ Paris; FYLA; ADVANTEST; Springer Nature; Soc Francaise Physique; Sorbonne Univ; Int Soc Infrared Millimeter \& Terahertz Waves; IEEE; GDR NANO THz MIR
2162-2027}, abstract = {

We demonstrate anisotropic THz spectroscopy of sucrose using newly developed compact discretely tunable THz sources for turn-key spectroscopic systems.

}, isbn = {978-1-5386-8285-2}, doi = {https://doi.org/10.1109/IRMMW-THz.2019.8874234}, author = {LaFave, T., Jr. and George, D. K. and Markelz, A. G. and McNee, Ian and Kozlov, Vladimir and Schunemann, Peter} } @article {267, title = {SUBCUBIC POWER DEPENDENCE OF 3RD-HARMONIC GENERATION FOR INPLANE, FAR-INFRARED EXCITATION OF INAS QUANTUM-WELLS}, journal = {Semiconductor Science and Technology}, volume = {9}, number = {5}, year = {1994}, note = {Sherwin, Mark S/Q-4762-2017
Sherwin, Mark S/0000-0002-3869-1893; Markelz, Andrea/0000-0003-0443-4319
S
8th International Conference on Hot Carriers in Semiconductors
Aug 16-20, 1993
Oxford univ, oxford, england
Sci \& engn res council; royal soc; brit council; oxford univ
4}, month = {May}, pages = {634-637}, abstract = {

Large third-order, free-carrier nonlinear susceptibilities, chi(3) (to approximately 0.2 esu), and subcubic dependence of the third-harmonic power on the incident intensity, have been observed between 19 cm-1 and 23 cm-1 for InAs/AlSb quantum wells with electron sheet densities between 2.5 x 10(12) cm-2 and 8 X 10(12) cm-2. We find that the transmission of the fundamental, and the samples{\textquoteright} DC conductivity, decrease with increasing incident intensity, indicating a large rise in the scattering rate. Using the intensity-dependent transmission to account for absorption in the sample is not sufficient to recover a cubic power law for the third-harmonic intensity. In addition, given the increased scattering rate indicated by the conductivity data, the bulk free-carrier chi(3) due to non-parabolicity should decrease dramatically with increasing fundamental intensity, contrary to our results. Thus, non-parabolicity alone cannot account for the observed third-harmonic response.

}, isbn = {0268-1242}, doi = {https://doi.org/10.1088/0268-1242/9/5S/063}, author = {Markelz, A. G. and Asmar, N. G. and Gwinn, E. G. and Sherwin, M. S. and Nguyen, C. and Kroemer, H.} } @article {298, title = {Site-selective oxygen-isotope substitution in YBa2Cu3O7-δ}, journal = {Physical Review B}, volume = {44}, year = {1991}, chapter = {9556}, abstract = {

We report selective substitution of oxygen-18 and oxygen-16 isotopes into the inequivalent oxygen lattice sites in YBa2Cu3O7-δ. The technique involves gas-phase diffusion and exploits the site dependence of diffusion rates. The CuO2-plane [O(2),O(3)] sites of YBa2Cu3O7-δ can be filled with 18O while the apical [O(4)] and CuO-chain sites [O(1)] contain 16O (the opposite distribution can also be made). The site-selective isotope occupation has been confirmed by Raman spectroscopy. Our method will permit experiments to determine the contributions of the different oxygen sites to the isotope effect, in order to locate the pairing interaction within the unit cell.

}, doi = {10.1103/PhysRevB.44.9556}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.44.9556}, author = {Morris, D. E. and Markelz, A. G. and Wei, J. Y. T. and Huitgren, C. T. and Nickel, J. H. and Hamilton, J. C. and McCarty, K. F.} } @article {279, title = {SMALL OXYGEN ISOTOPE SHIFT IN YBA2CU3O7}, journal = {Physical Review B}, volume = {37}, number = {10}, year = {1988}, note = {Markelz, Andrea/0000-0003-0443-4319
B
74}, month = {Apr 1}, pages = {5936-5939}, isbn = {0163-1829}, doi = {10.1103/physrevb.37.5936}, author = {Morris, D. E. and Kuroda, R. M. and Markelz, A. G. and Nickel, J. H. and Wei, J. Y. T.} } @article {277, title = {SPECIFIC-HEAT MEASUREMENTS ON SUPERCONDUCTING BI-CA-SR-CU AND TL-CA-BA-CU OXIDES - ABSENCE OF A LINEAR TERM IN THE SPECIFIC-HEAT OF BI-CA-SR-CU OXIDES}, journal = {Physical Review B}, volume = {38}, number = {16}, year = {1988}, note = {Fisher, Robert Anthony/H-6779-2019
Markelz, Andrea/0000-0003-0443-4319
B
68}, month = {Dec 1}, pages = {11942-11945}, isbn = {0163-1829}, doi = {10.1103/PhysRevB.38.11942}, author = {Fisher, R. A. and Kim, S. and Lacy, S. E. and Phillips, N. E. and Morris, D. E. and Markelz, A. G. and Wei, J. Y. T. and Ginley, D. S.} }