01315nas a2200337   4500008004500000020002200045245009400067210006900161260006300230490001000293520025200303653001500555653001700570653001600587653002600603653004400629653001400673653001900687100001900706700001900725700002000744700001400764700001600778700001500794700001900809700000900828700003000837700003600867700002500903856004900928       2019                        Engldsh    a978-1-5106-2632-400aTunable Compact Narrow Band THz Sources for Frequency Domain THz Anisotropic Spectroscopy0 aTunable Compact Narrow Band THz Sources for Frequency Domain THz  aBaltimore, MDbSpie-Int Soc Optical EngineeringcApr 15-170 v109833 a<p>We demonstrate frequency domain THz anisotropy signature detection for protein crystal models using newly developed compact tunable narrow band THz sources based on Orientation Patterned Gallium Phosphide for turn-key spectroscopic systems.</p>10aanisotropy10abiomolecules10afemtosecond10aoptical rectification10aorientation patterned gallium phosphide10aTerahertz10aTHz generation1 aGeorge, D., K.1 aLaFave, T., J.1 aMarkelz, A., G.1 aMcNee, I.1 aTekavec, P.1 aKozlov, V.1 aSchunemann, P.1 aSpie1 aBuffalo, Dept, Phys Buffa1 aInstruments, Eugene, O. R. U. S1 aSyst, P., O. B. Nash  uhttps://markelz.physics.buffalo.edu/node/18500501nas a2200157   4500008004100000245006500041210006500106260001200171100001900183700001400202700001600216700001500232700001900247700002000266856005700286       2019                        eng d00aTunable narrow band sources for anisotropic THz spectroscopy0 aTunable narrow band sources for anisotropic THz spectroscopy  c02/20191 aGeorge, D., K.1 aMcNee, I.1 aTekavec, P.1 aKozlov, V.1 aSchunemann, P.1 aMarkelz, A., G.  uhttps://meetings.aps.org/Meeting/MAR19/Session/S23.201432nas a2200301   4500008004500000020002200045245011500067210006900182260004900251490001000300520047300310653001500783653001700798653001600815653002600831653004400857653001400901653001900915100001400934700001600948700001500964700002000979700001900999700001901018700002301037700002101060856004901081       2019                        Engldsh    a978-1-5106-2447-400aTunable narrowband THz generation in orientation patterned gallium phosphide for THz anisotropy identification0 aTunable narrowband THz generation in orientation patterned galli  aBellinghambSpie-Int Soc Optical Engineering0 v109023 a<p>We demonstrate tunable narrowband THz generation by optical rectification of a femtosecond pulse in Orientation Patterned Gallium Phosphide. Center frequencies of 0.9 - 3.8 THz with average power up to 15 mu W were achieved using a 1.064 mu m fiber laser for the pump laser. Biomolecular characterization for an early application of this system is also shown in this work by anisotropic spectroscopic signature detection of molecular crystals in the THz region.</p>10aanisotropy10abiomolecules10afemtosecond10aoptical rectification10aorientation patterned gallium phosphide10aTerahertz10aTHz generation1 aMcNee, I.1 aTekavec, P.1 aKozlov, V.1 aMarkelz, A., G.1 aGeorge, D., K.1 aSchunemann, P.1 aSchunemann, P., G.1 aSchepler, K., L.  uhttps://markelz.physics.buffalo.edu/node/23600791nas a2200181   4500008004500000020002200045245008000067210006900147260001900216520022200235100001900457700002000476700001400496700001600510700001500526700001900541856004900560       2018                        Engldsh    a978-1-5386-3809-500aTHz Anisotropy Identification using Tunable Compact Narrow Band THz Sources0 aTHz Anisotropy Identification using Tunable Compact Narrow Band   aNew YorkbIeee3 a<p>We demonstrate THz anisotropy signature determination of a protein crystal model using newly developed compact tunable narrow band THz sources for turn-key spectroscopic systems for the bio molecular community.</p>1 aGeorge, D., K.1 aMarkelz, A., G.1 aMcNee, I.1 aTekavec, P.1 aKozlov, V.1 aSchunemann, P.  uhttps://markelz.physics.buffalo.edu/node/22601122nas a2200169   4500008004100000020001400041245009100055210006900146260001300215300001200228490000600240520059300246100002700839700001700866700002000883856004900903       2015                        eng d  a1867-245000aTerahertz optical measurements of correlated motions with possible allosteric function0 aTerahertz optical measurements of correlated motions with possib  c2015-Jun  a201-2160 v73 a<p>A suggested mechanism for allosteric response is the distortion of the energy landscape with agonist binding changing the protein structure's access to functional configurations. Intramolecular vibrations are indicative of the energy landscape and may have trajectories that enable functional conformational change. Here, we discuss the development of an optical method to measure the intramolecular vibrations in proteins, namely, crystal anisotropy terahertz microscopy, and the various approaches which can be used to identify the spectral data with specific structural motions.</p>1 aNiessen, Katherine, A.1 aXu, Mengyang1 aMarkelz, A., G.  uhttps://markelz.physics.buffalo.edu/node/25500488nas a2200145   4500008004100000245009100041210006900132260001200201300001400213490000600227100002000233700001100253700002000264856005800284       2015                        eng d00aTerahertz Optical Measurements of Correlated Motions with Possible Allosteric Function0 aTerahertz Optical Measurements of Correlated Motions with Possib  c04/2015  a201–2160 v71 aNiessen, K., A.1 aXu, M.1 aMarkelz, A., G.  uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425745/00412nas a2200121   4500008004100000245005500041210005500096260003900151300001200190100001900202700002000221856004900241       2013                        eng d00aTerahertz Spectroscopy of Liquids and Biomolecules0 aTerahertz Spectroscopy of Liquids and Biomolecules  aBerlin-HeidelbergbSpringer-Verlag  a229-2501 aGeorge, D., K.1 aMarkelz, A., G.  uhttps://markelz.physics.buffalo.edu/node/30100379nas a2200109   4500008004100000245006000041210005700101260001300158490002900171100002000200856004900220       2012                        eng d00aTerahertz / Far Infrared Spectroscopy: Protein Dynamics0 aTerahertz Far Infrared Spectroscopy Protein Dynamics  bSpringer0 ved. Gordon C. K. Roberts1 aMarkelz, A., G.  uhttps://markelz.physics.buffalo.edu/node/30201418nas a2200289   4500008004500000020001400045245011000059210006900169260000800238300000600246490000800252520061600260653001100876653001200887100002000899700001800919700001200937700001900949700001900968700001500987700001101002700001401013700002001027700001101047700002101058856004901079       2012                        Engldsh    a0031-900700aTerahertz Response and Colossal Kerr Rotation from the Surface States of the Topological Insulator Bi2Se30 aTerahertz Response and Colossal Kerr Rotation from the Surface S  cFeb  a50 v1083 a<p>We report the THz response of thin films of the topological insulator Bi2Se3. At low frequencies, transport is essentially thickness independent showing the dominant contribution of the surface electrons. Despite their extended exposure to ambient conditions, these surfaces exhibit robust properties including narrow, almost thickness-independent Drude peaks, and an unprecedentedly large polarization rotation of linearly polarized light reflected in an applied magnetic field. This Kerr rotation can be as large as 65 degrees and can be explained by a cyclotron resonance effect of the surface states.</p>10abi2te310aPhysics1 aAguilar, R., V.1 aStier, A., V.1 aLiu, W.1 aBilbro, L., S.1 aGeorge, D., K.1 aBansal, N.1 aWu, L.1 aCerne, J.1 aMarkelz, A., G.1 aOh, S.1 aArmitage, N., P.  uhttps://markelz.physics.buffalo.edu/node/22101467nas a2200349   4500008004500000020001400045245004900059210004900108260000800157300000600165490000700171520058300178653001300761653001200774653002900786653001200815653001700827653001400844653002300858653001700881653001400898100001700912700001800929700001500947700001800962700001800980700001600998700001701014700002001031700001701051856004901068       2008                        Engldsh    a0003-695100aTerahertz response of quantum point contacts0 aTerahertz response of quantum point contacts  cJun  a30 v923 a<p>We measure a clear terahertz response in the low-temperature conductance of a quantum point contact at 1.4 and 2.5 THz. We show that this photoresponse does not arise from a heating effect, but that it is instead excellently described by a classical model of terahertz-induced gate-voltage rectification. This effect is distinct from the rectification mechanisms that have been studied previously, being determined by the phase-dependent interference of the source drain and gate voltage modulations induced by the terahertz field. (C) 2008 American Institute of Physics.</p>10adetector10adevices10afield-effect transistors10aPhysics10aplasma-waves10aradiation10aresonant detection10asubterahertz10atransport1 aSong, J., W.1 aKabir, N., A.1 aKawano, Y.1 aIshibashi, K.1 aAizin, G., R.1 aMourokh, L.1 aReno, J., L.1 aMarkelz, A., G.1 aBird, J., P.  uhttps://markelz.physics.buffalo.edu/node/24301967nas a2200349   4500008004500000020001400045245009200059210006900151260000800220300001400228490000700242520094400249653001501193653002101208653002701229653001201256653002701268653002101295653003401316653002301350653003001373653002601403653002201429653001401451100001301465700001401478700001701492700001701509700002001526700002201546856004901568       2008                        Engldsh    a0006-349500aTerahertz spectroscopy of bacteriorhodopsin and rhodopsin: Similarities and differences0 aTerahertz spectroscopy of bacteriorhodopsin and rhodopsin Simila  cApr  a3217-32260 v943 a<p>We studied the low-frequency terahertz spectroscopy of two photoactive protein systems, rhodopsin and bacteriorhodopsin, as a means to characterize collective low-frequency motions in helical transmembrane proteins. From this work, we found that the nature of the vibrational motions activated by terahertz radiation is surprisingly similar between these two structurally similar proteins. Specifically, at the lowest frequencies probed, the cytoplasmic loop regions of the proteins are highly active; and at the higher terahertz frequencies studied, the extracellular loop regions of the protein systems become vibrationally activated. In the case of bacteriorhodopsin, the calculated terahertz spectra are compared with the experimental terahertz signature. This work illustrates the importance of terahertz spectroscopy to identify vibrational degrees of freedom which correlate to known conformational changes in these proteins.</p>10aBiophysics10abovine rhodopsin10aconformational-changes10aelastic10afrequency normal-modes10alight activation10amolecular-dynamics simulation10aneutron-scattering10aprotein-coupled receptors10atransmembrane helices10avibrational-modes10awild-type1 aBalu, R.1 aZhang, H.1 aZukowski, E.1 aChen, J., Y.1 aMarkelz, A., G.1 aGregurick, S., K.  uhttps://markelz.physics.buffalo.edu/node/22201209nas a2200253   4500008004500000020001400045245006500059210006500124260000800189300000600197490000700203520054700210653001300757653001300770653001200783653001700795653001000812100001700822700001700839700001500856700001500871700002000886856004900906       2007                        Engldsh    a0003-695100aTerahertz dielectric assay of solution phase protein binding0 aTerahertz dielectric assay of solution phase protein binding  cJun  a30 v903 a<p>The authors demonstrate a method for rapid determination of protein-ligand binding on solution phase samples using terahertz dielectric spectroscopy. Measurements were performed using terahertz time domain spectroscopy on aqueous solutions below the liquid-solid transition for water. Small ligand binding sensitivity was demonstrated using triacetylglucosamine and hen egg white lysozyme with a decrease in dielectric response with binding. The magnitude of the change increases with frequency. (c) 2007 American Institute of Physics.</p>10adynamics10alysozyme10aPhysics10aspectroscopy10awater1 aChen, J., Y.1 aKnab, J., R.1 aYe, S., J.1 aHe, Y., F.1 aMarkelz, A., G.  uhttps://markelz.physics.buffalo.edu/node/22301575nas a2200337   4500008004500000020001400045245011100059210006900170260000800239300000600247490000700253520062400260653002900884653002200913653001200935653001700947653001400964653002300978653001701001100001801018700001301036700001701049700001701066700002001083700001701103700001701120700001601137700001801153700001701171856004901188       2006                        Engldsh    a0003-695100aTerahertz transmission characteristics of high-mobility GaAs and InAs two-dimensional-electron-gas systems0 aTerahertz transmission characteristics of highmobility GaAs and   cSep  a30 v893 a<p>Frequency-dependent complex conductivity of high-mobility GaAs and InAs two-dimensional-electron-gas (2DEG) systems is studied by terahertz time domain spectroscopy. Determining the momentum relaxation time from a Drude model, the authors find a lower value than that from dc measurements, particularly at high frequencies/low temperatures. These deviations are consistent with the ratio tau(t)/tau(q,) where tau(q) is the full scattering time. This suggests that small-angle scattering leads to weaker heating of 2DEGs at low temperatures than expected from dc mobilit9y. (c) 2006 American Institute of Physics.</p>10afield-effect transistors10aphotoconductivity10aPhysics10aplasma-waves10aradiation10aresonant detection10asubterahertz1 aKabir, N., A.1 aYoon, Y.1 aKnab, J., R.1 aChen, J., Y.1 aMarkelz, A., G.1 aReno, J., L.1 aSadofyev, Y.1 aJohnson, S.1 aZhang, Y., H.1 aBird, J., P.  uhttps://markelz.physics.buffalo.edu/node/22901843nas a2200193   4500008004100000245010000041210006900141260001900210300001900229490000800248520123500256100001601491700001701507700001401524700002401538700001801562700002001580856004901600       2004                        eng d00aTerahertz measurements of the Photoactive Protein Bacteriorhodopsin mutant D96N: M and P states0 aTerahertz measurements of the Photoactive Protein Bacteriorhodop  aWarrendale, PA  apages261–2670 v8263 a<div id="Abs1-content" class="c-article-section__content"><p>We use terahertz (THz) spectroscopy as a biomaterials characterization tool. Previously we have shown a strong contrast between the THz dielectric response for wild type (WT) and D96N mutant of bacteriorhodopsin. In those studies we observed a large increase in the THz absorbance of WT with excitation to thermally captured photo-intermediates whereas no such increase in absorbance was observed for the mutant D96N. These results suggest that the THz response is sensitive to structural changes and relative flexibility of biomolecules. However the photo-intermediate populations of the WT and D96N samples were not equivalent in those measurements. While the WT samples had relaxed (bR), M and P state intermediates present, the D96N samples had only bR and M states. Here we present terahertz absorbance measurements of D96N as a function of M and P state populations at room temperature. The THz response is constant for intermediate states populations up to 23% M state and up to 30% P state. These results verify that there is a fundamental difference in the conformational dynamics as measured by THz dielectric response for a single residue mutation.</p></div>1 aChen, C.-Y.1 aKnab, J., R.1 aCerne, J.1 aHillebrecht, J., R.1 aBirge, R., R.1 aMarkelz, A., G.  uhttps://markelz.physics.buffalo.edu/node/31000492nas a2200133   4500008004100000245010100041210006900142260003000211100002000241700001600261700001700277700001500294856004900309       2004                        eng d00aThz Dielectric Response As A Function Of Protein Hydration: Intramolecular Coupling Contribution0 aThz Dielectric Response As A Function Of Protein Hydration Intra  aPhiladelphia, PAc10/20041 aMarkelz, A., G.1 aChen, J.-Y.1 aKnab, J., R.1 aMaeder, M.  uhttps://markelz.physics.buffalo.edu/node/31200371nas a2200109   4500008004100000245005100041210005100092490000700143100002000150700002100170856007000191       2003                        eng d00aTerahertz Applications to Biomolecular Sensing0 aTerahertz Applications to Biomolecular Sensing0 v131 aMarkelz, A., G.1 aWhitmire, S., E.  uhttps://www.worldscientific.com/doi/abs/10.1142/S012915640300210100445nas a2200145   4500008004100000245005300041210005300094260002200147100001600169700001200185700001900197700001400216700002000230856004900250       2003                        eng d00aTerahertz Biosensors based on Xerogel Substrates0 aTerahertz Biosensors based on Xerogel Substrates  aSanta Barbara, CA1 aChen, J.-Y.1 aCox, W.1 aBright, F., V.1 aCerne, J.1 aMarkelz, A., G.  uhttps://markelz.physics.buffalo.edu/node/31400514nas a2200145   4500008004100000245008800041210006900129260003000198300001200228100001700240700002000257700002400277700001800301856004900319       2001                        eng d00aTerahertz Time domain spectroscopy of the M intermediate state of Bacteriorhodopsin0 aTerahertz Time domain spectroscopy of the M intermediate state o  aToulouse, Francec09/2001  a345-3481 aWhitmire, S.1 aMarkelz, A., G.1 aHillebrecht, J., R.1 aBirge, R., R.  uhttps://markelz.physics.buffalo.edu/node/31601241nas a2200229   4500008004500000020001400045245009400059210006900153260000800222300001400230490000700244520056400251653001100815653001500826653001200841653001100853653002700864653003000891100002000921700002100941856004900962       1998                        Engldsh    a0003-695100aTemperature-dependent terahertz output from semi-insulating GaAs photoconductive switches0 aTemperaturedependent terahertz output from semiinsulating GaAs p  cMay  a2229-22310 v723 a<p>The temperature dependence of the terahertz (THz) output power and spectra from biased photoconductive switches was measured for several antenna gap widths and applied biases. The spectrally integrated THz output had a nonmonotonic temperature dependence in all cases with the value increasing by a factor of 3 from room temperature to 150 K for low biases and 100 K at high biases. An abrupt decrease in output power occurs below 90 K, and the spectrum shifts to lower frequencies as the temperature is lowered. (C) 1998 American Institute of Physics.</p>10adomain10ageneration10aPhysics10apulses10asemiconductor surfaces10atransmission spectroscopy1 aMarkelz, A., G.1 aHeilweil, E., J.  uhttps://markelz.physics.buffalo.edu/node/27001436nas a2200241   4500008004500000020001400045245009100059210006900150260000800219300001200227490000700239520073900246653001800985653001201003100001801015700001401033700002001047700001801067700002001085700002001105700002001125856004901145       1996                        Engldsh    a0003-695100aTemperature of quasi-two-dimensional electron gases under steady-state terahertz drive0 aTemperature of quasitwodimensional electron gases under steadyst  cFeb  a829-8310 v683 a<p>We use photoluminescence to study the time-average energy distribution of electrons in the presence of strong steady-state drive at terahertz (THz) frequencies, in a modulation-doped 125 Angstrom AlGaAs/GaAs square well that is held at low lattice temperature TL. We find that the energy distribution can be characterized by an effective electron temperature, T-e(&gt;T-L), that agrees well with values estimated from the THz-illuminated, dc conductivity. This agreement indicates that under strong THz drive, LO phonon scattering dominates both energy and momentum relaxation; that the carrier distribution maintains a heated, thermal form; and that phonon drift effects are negligible. (C) 1996 American Institute of Physics.</p>10ahot-electrons10aPhysics1 aAsmar, N., G.1 aCerne, J.1 aMarkelz, A., G.1 aGwinn, E., G.1 aSherwin, M., S.1 aCampman, K., L.1 aGossard, A., C.  uhttps://markelz.physics.buffalo.edu/node/25800605nas a2200169   4500008004100000245009100041210006900132260003100201300001200232490005000244100001800294700002000312700002000332700001800352700001400370856005100384       1996                        eng d00aThird Harmonic Generation in a Gaas/Algaas Superlattice in the Bloch Oscillator Regime0 aThird Harmonic Generation in a GaasAlgaas Superlattice in the Bl  aNew York, NYbPlenum Press  a161-1630 veds. Hess, Karl, Leburton, J.P., Ravaioli, U.1 aWanke, M., C.1 aMarkelz, A., G.1 aUnterrainer, K.1 aAllen, S., J.1 aBhatt, R.  uhttps://www.springer.com/gp/book/9781461380351