01555nas a2200169 4500008004100000245006300041210006200104300001600166490000800182520105800190100001901248700001701267700001501284700001701299700002001316856004901336 2021 eng d00aFunctional-State Dependence of Picosecond Protein Dynamics0 aFunctionalState Dependence of Picosecond Protein Dynamics a11134-111400 v1253 a
We examine temperature-dependent picosecond dynamics of two benchmarking proteins lysozyme and cytochrome c using temperature-dependent terahertz permittivity measurements. We find that a double Arrhenius temperature dependence with activation energies E1 ∼ 0.1 kJ/mol and E2 ∼ 10 kJ/mol fits the folded and ligand-free state response. The higher activation energy is consistent with the so-called protein dynamical transition associated with beta relaxations at the solvent–protein interface. The lower activation energy is consistent with correlated structural motions. When the structure is removed by denaturing, the lower-activation-energy process is no longer present. Additionally, the lower-activation-energy process is diminished with ligand binding but not for changes in the internal oxidation state. We suggest that the lower-energy activation process is associated with collective structural motions that are no longer accessible with denaturing or binding.
1 aGeorge, D., K.1 aChen, J., Y.1 aHe, Yunfen1 aKnab, J., R.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/54501859nas a2200241 4500008004500000020001400045245011000059210006900169260000800238300001400246490000800260520114300268653001501411100002101426700001501447700001601462700001301478700001901491700002201510700001601532700002001548856004901568 2020 Engldsh a0006-349500aEvidence of Intramolecular Structural Stabilization in Light Activated State of Orange Carotenoid Protein0 aEvidence of Intramolecular Structural Stabilization in Light Act cFeb a208A-208A0 v1183 aOrange carotenoid protein (OCP) controls efficiency of the light harvesting antenna, the phycobilisome (PBS), in diverse cyanobacteria and prevents oxidative damage. It is the only known photoactive protein that uses a carotenoid, canthaxanthin, as its chromophore. The structure of OCP consists of two globular domains, connected by an unstructured loop, that forms a hydrophobic pocket for the carotenoid. In low light, canthaxanthin bound OCP is inactive and appears orange. Illumination by strong light results in an active state that interacts with the PBS to induce fluorescence quenching, a red appearance and conformational changes that include a 12Å shift by canthaxanthin into the N-terminal domain. Terahertz (THz) dynamical transition measurements and anisotropic terahertz microscopy are used to measure the intramolecular structural dynamics in the inactive and active states, which can be induced by photoexcitation or chaotropic salts. The measurements indicate that the active state has a decrease in structural flexibility, which may be related to enhanced interactions with the PBS.
10aBiophysics1 aMcKinney, J., A.1 aSharma, A.1 aCrossen, K.1 aDeng, Y.1 aGeorge, D., K.1 aLechno-Yossef, S.1 aKerfeld, C.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/25302182nas a2200301 4500008004500000020001400045245011000059210006900169260000800238300000600246490000800252520133400260653002201594653001201616100001801628700001201646700001701658700001401675700001801689700001701707700001901724700002001743700002101763700001401784700001901798700001401817856004901831 2020 Engldsh a2469-995000aLinear dichroism infrared resonance in overdoped, underdoped, and optimally doped cuprate superconductors0 aLinear dichroism infrared resonance in overdoped underdoped and cAug a60 v1023 aBy measuring the polarization changes in terahertz, infrared, and visible radiation over an extended energy range (3-2330 meV), we observe symmetry breaking in cuprate high-temperature superconductors over wide energy, doping, and temperature ranges. We measure the polarization rotation (Re[theta(F)]) and ellipticity (Im[theta(F)]) of transmitted radiation through thin films as the sample is rotated. We observe a twofold rotational symmetry in theta(F), which is associated with linear dichroism (LD) and occurs when electromagnetic radiation polarized along one direction is absorbed more strongly than radiation polarized in the perpendicular direction. Such polarization anisotropies can be generally associated with symmetry breakings. We measure the amplitude of the LD signal and study its temperature, energy, and doping dependence. The LD signal shows a resonant behavior with a peak in the few hundred meV range, which is coincident with the midinfrared optical feature that has been associated with the formation of the pseudogap state. The strongest LD signal is found in underdoped films, although it is also observed in optimally and overdoped samples. The LD signal is consistent with an electronic nematic order which is decoupled from the crystallographic axes as well as novel magnetoelectric effects.
10aMaterials Science10aPhysics1 aMukherjee, A.1 aSeo, J.1 aArik, M., M.1 aZhang, H.1 aZhang, C., C.1 aKirzhner, T.1 aGeorge, D., K.1 aMarkelz, A., G.1 aArmitage, N., P.1 aKoren, G.1 aWei, J., Y. T.1 aCerne, J. uhttps://markelz.physics.buffalo.edu/node/23800443nas a2200157 4500008004100000245004800041210004000089490000800129100001500137700001900152700001600171700001700187700001600204700001600220856004900236 2020 eng d00aIs the Protein Dynamical Transition useful?0 aProtein Dynamical Transition useful0 v1181 aSharma, A.1 aGeorge, D., K.1 aCrossen, K.1 aMcKinney, J.1 aKerfeld, C.1 aMarkelz, A. uhttps://markelz.physics.buffalo.edu/node/28200655nas a2200229 4500008004100000020001400041245004500055210004500100300000900145490000700154100002600161700001700187700002100204700002100225700003300246700002100279700001700300700001600317700002000333700002300353856004900376 2019 eng d a2041-172300aProtein and RNA dynamical fingerprinting0 aProtein and RNA dynamical fingerprinting a1-100 v101 aNiessen, Katherine, A1 aXu, Mengyang1 aGeorge, Deepu, K1 aChen, Michael, C1 aFerré-D’Amaré, Adrian, R1 aSnell, Edward, H1 aCody, Vivian1 aPace, James1 aSchmidt, Marius1 aMarkelz, Andrea, G uhttps://markelz.physics.buffalo.edu/node/19904125nas a2200841 4500008004500000020001400045245005400059210005000113260000800163300000700171490000700178520199900185653001202184653001502196653002202211653001502233653001602248653002902264653001202293653002702305653001402332653001902346653001402365653000802379653002902387100002002416700002102436700002102457700001902478700002102497700001502518700001602533700001502549700001802564700002102582700002102603700002302624700001602647700002602663700001402689700001702703700002402720700001602744700001302760700002602773700001902799700001402818700002002832700001902852700002002871700002002891700001402911700001902925700001602944700001202960700001802972700001902990700001603009700001403025700002003039700001503059700001403074700001303088700001503101700001403116700001403130700001603144700001503160700001503175700002303190700002103213856004903234 2017 Engldsh a0022-372700aThe 2017 terahertz science and technology roadmap0 a2017 terahertz science and technology roadmap cFeb a490 v503 aScience and technologies based on terahertz frequency electromagnetic radiation (100 GHz-30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies.
10aex-vivo10ageneration10ametal wave-guides10anear-field10aperformance10aphotoconductive emitters10aPhysics10aquantum-cascade lasers10aradiation10asemiconductors10aTerahertz10athz10atime-domain spectroscopy1 aDhillon, S., S.1 aVitiello, M., S.1 aLinfield, E., H.1 aDavies, A., G.1 aHoffmann, M., C.1 aBooske, J.1 aPaoloni, C.1 aGensch, M.1 aWeightman, P.1 aWilliams, G., P.1 aCastro-Camus, E.1 aCumming, D., R. S.1 aSimoens, F.1 aEscorcia-Carranza, I.1 aGrant, J.1 aLucyszyn, S.1 aKuwata-Gonokami, M.1 aKonishi, K.1 aKoch, M.1 aSchmuttenmaer, C., A.1 aCocker, T., L.1 aHuber, R.1 aMarkelz, A., G.1 aTaylor, Z., D.1 aWallace, V., P.1 aZeitler, J., A.1 aSibik, J.1 aKorter, T., M.1 aEllison, B.1 aRea, S.1 aGoldsmith, P.1 aCooper, K., B.1 aAppleby, R.1 aPardo, D.1 aHuggard, P., G.1 aKrozer, V.1 aShams, H.1 aFice, M.1 aRenaud, C.1 aSeeds, A.1 aStohr, A.1 aNaftaly, M.1 aRidler, N.1 aClarke, R.1 aCunningham, J., E.1 aJohnston, M., B. uhttps://markelz.physics.buffalo.edu/node/22400412nas a2200133 4500008004100000245006300041210006300104100001700167700001900184700001100203700001700214700001800231856002900249 2012 eng d00aFunctional State Dependence of Picosecond Protein Dynamics0 aFunctional State Dependence of Picosecond Protein Dynamics1 aChen, J., Y.1 aGeorge, D., K.1 aHe, Y.1 aKnab, J., R.1 aMarkelz, A.G. uhttp://arxiv.org/005439400733nas a2200217 4500008004100000245011300041210006900154260003400223100001800257700001800275700001900293700002100312700001900333700002300352700002000375700001700395700002000412700002000432700001400452856004900466 2012 eng d00aMulti-component response in multilayer graphene revealed through terahertz and infrared magneto-spectroscopy0 aMulticomponent response in multilayer graphene revealed through aWollongong, Australiac9/20121 aEllis, C., T.1 aStier, A., V.1 aGeorge, D., K.1 aTischler, J., G.1 aGlaser, E., R.1 aMyers-Ward, R., L.1 aTedesco, J., L.1 aEddy, C., R.1 aGaskill, D., K.1 aMarkelz, A., G.1 aCerne, J. uhttps://markelz.physics.buffalo.edu/node/30701418nas 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 aWe 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.
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/22100526nas a2200169 4500008004100000020001400041245007100055210006900126300001400195490000800209100001500217700001400232700002000246700001800266700002300284856004900307 2011 eng d a0006-349500aEvidence of protein collective motions on the picosecond timescale0 aEvidence of protein collective motions on the picosecond timesca a1058-10650 v1001 aHe, Yunfen1 aChen, J-Y1 aKnab, Joseph, R1 aZheng, Wenjun1 aMarkelz, Andrea, G uhttps://markelz.physics.buffalo.edu/node/18700927nas a2200169 4500008004500000020002200045245009300067210006900160260001900229520038000248100001800628700001500646700002000661700001400681700001300695856004900708 2011 Engldsh a978-1-4577-0509-000aMagneto Optical Polarization Measurements using THz Polarization Modulation Spectroscopy0 aMagneto Optical Polarization Measurements using THz Polarization aNew YorkbIeee3 aWe report a new broad band technique for rapidly measuring the complex Faraday and Kerr rotations in materials such as topological insulators and graphene, combining the distinct advantages of THz time domain spectroscopy and polarization modulation techniques. The performance of the system is demonstrated using GaAs two dimensional electron gas in a magnetic field.
1 aStier, A., V.1 aGeorge, D.1 aMarkelz, A., G.1 aCerne, J.1 aKoch, M. uhttps://markelz.physics.buffalo.edu/node/24401840nas a2200157 4500008004100000245008700041210006900128490000600197520134000203100001101543700001601554700001701570700001401587700001801601856006301619 2010 eng d00aWhy is THz Sensitive to Protein Functional States? Oxidation State of Cytochrome C0 aWhy is THz Sensitive to Protein Functional States Oxidation Stat0 v33 aWe 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 H2O/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.
1 aHe, Y.1 aChen, J.-Y.1 aKnab, J., R.1 aZheng, W.1 aMarkelz, A.G. uhttp://www.tstnetwork.org/10.11906/TST.149-162.2010.12.15/01967nas 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 aWe 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.
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/22200593nas a2200169 4500008004100000245007800041210006900119260004100188300001200229490005800241100002000299700001600319700001700335700001100352700001100363856004900374 2007 eng d00aDevelopment of Tagless Biosensors for Detecting the Presence of Pathogens0 aDevelopment of Tagless Biosensors for Detecting the Presence of aDordrecht, The NetherlandsbSpringer a123-1340 ved X.-C. Zhang, R. E. Miles, H. Eisele and A. Krotkus1 aMarkelz, A., G.1 aChen, J.-Y.1 aKnab, J., R.1 aHe, Y.1 aYe, S. uhttps://markelz.physics.buffalo.edu/node/30301240nas a2200169 4500008004100000020001400041245006600055210006600121300001400187490000800201520070900209100002400918700002100942700002000963700001500983856007200998 2007 eng d a0009-261400aProtein dynamical transition in terahertz dielectric response0 aProtein dynamical transition in terahertz dielectric response a413 - 4170 v4423 aThe 200K protein dynamical transition is observed for the first time in the terahertz dielectric response. The complex dielectric permittivity ε=ε′+iε″ is determined in the 0.2–2.0THz and 80–294K ranges. ε″ has a linear temperature dependence up to 200K then sharply increases. The low temperature linear dependence in ε″ suggests anharmonicity for temperatures 80K<t<180k, challenging="" the="" assumed="" harmonicity="" below="" 200k.="" temperature="" dependence="" is="" consistent="" with="" thermally="" activated="" sidechain="" motions="" and="" shows="" involved="" in="" dynamical="" transition="" extend="" to="" subpicosecond="" time="" scales.<="" div="">
1 aMarkelz, Andrea, G.1 aKnab, Joseph, R.1 aChen, Jing, Yin1 aHe, Yunfen uhttps://www.sciencedirect.com/science/article/pii/S000926140700680X01209nas a2200253 4500008004500000020001400045245006500059210006500124260000800189300000600197490000700203520054700210653001300757653001300770653001200783653001700795653001000812100001700822700001700839700001500856700001500871700002000886856004900906 2007 Engldsh a0003-695100aTerahertz dielectric assay of solution phase protein binding0 aTerahertz dielectric assay of solution phase protein binding cJun a30 v903 aThe 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.
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/22300480nas a2200157 4500008004100000020001400041245006000055210006000115300001400175490000700189100002000196700001900216700001500235700002300250856004900273 2007 eng d a0018-921900aTerahertz measurements of protein relaxational dynamics0 aTerahertz measurements of protein relaxational dynamics a1605-16100 v951 aKnab, Joseph, R1 aChen, Jing-Yin1 aHe, Yunfen1 aMarkelz, Andrea, G uhttps://markelz.physics.buffalo.edu/node/19100473nas a2200145 4500008004100000020001400041245007700055210006900132300001400201490000700215100001700222700001900239700002000258856004900278 2006 eng d a0006-349500aHydration dependence of conformational dielectric relaxation of lysozyme0 aHydration dependence of conformational dielectric relaxation of a2576-25810 v901 aKnab, Joseph1 aChen, Jing-Yin1 aMarkelz, Andrea uhttps://markelz.physics.buffalo.edu/node/18900541nas a2200169 4500008004100000020001500041245008500056210006900141260000900210300001200219100002000231700001900251700001400270700001500284700002300299856004900322 2006 eng d a142440399500aProtein conformational dynamics measured with terahertz time domain spectroscopy0 aProtein conformational dynamics measured with terahertz time dom bIEEE a183-1831 aKnab, Joseph, R1 aChen, Jing-Yin1 aYe, Shuji1 aHe, Yunfen1 aMarkelz, Andrea, G uhttps://markelz.physics.buffalo.edu/node/19201575nas 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 aFrequency-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.
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/22900491nas a2200169 4500008004100000245005700041210005600098260001900154100001100173700001300184700001600197700001300213700001400226700001200240700002000252856004900272 2006 eng d00aUltrafast Carriers Dynamics in GaSb/Mn Random Alloys0 aUltrafast Carriers Dynamics in GaSbMn Random Alloys aVienna Austria1 aYe, S.1 aKnab, J.1 aChen, J.-Y.1 aWang, S.1 aCheon, M.1 aLuo, H.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/30801577nas a2200181 4500008004100000245006000041210006000101260005000161300001000211490002000221520103000241100001601271700001701287700001101304700001101315700002001326856004901346 2006 eng d00aUsing terahertz spectroscopy as a protein binding assay0 aUsing terahertz spectroscopy as a protein binding assay a San Jose, California, United Statesc02/2006 a35-420 vProc SPIE 6080,3 aThe vibrational modes corresponding to protein tertiary structural motion lay in the far infrared or terahertz frequency range. These collective large scale motions depend on global structure and thus will necessarily be perturbed by ligand binding events. We discuss the use of terahertz dielectric spectroscopy to measure these vibrational modes and the sensitivity of the technique to changes in protein conformation, oxidation state and environment. A challenge of applying this sensitivity as a spectroscopic assay for ligand binding is the sensitivity of the technique to both bulk water and water bound to the protein. This sensitivity can entirely obscure the signal from the protein or protein-ligand complex itself, thus necessitating sophisticated sample preparation making the technique impractical for industrial applications. We discuss methods to overcome this background and demonstrate how terahertz spectroscopy can be used to quickly assay protein binding for proteomics and pharmaceutical research.
1 aChen, J.-Y.1 aKnab, J., R.1 aYe, S.1 aHe, Y.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/30900541nas a2200157 4500008004100000245008100041210006900122260005100191300001100242490000900253100001700262700001600279700001900295700002000314856004900334 2005 eng d00aCritical hydration and temperature effects on terahertz biomolecular sensing0 aCritical hydration and temperature effects on terahertz biomolec bInternational Society for Optics and Photonics a59950P0 v59951 aKnab, Joseph1 aShah, Binni1 aChen, Jing-Yin1 aMarkelz, Andrea uhttps://markelz.physics.buffalo.edu/node/19001840nas a2200313 4500008004500000020001400045245009000059210006900149260000800218300000600226490000700232520100400239653001501243653001201258653001701270653000801287653001301295653002801308653001001336653001201346653002401358653001701382653001001399100001701409700001701426700001401443700002001457856004901477 2005 Engldsh a1539-375500aLarge oxidation dependence observed in terahertz dielectric response for cytochrome c0 aLarge oxidation dependence observed in terahertz dielectric resp cOct a40 v723 aFar infrared dielectric response is used to characterize the collective mode density of states for cytochrome c as a function of oxidation state and hydration using terahertz time domain spectroscopy. A strong absorbance and refractive index increase was observed with the oxidation. A simple phenomenological fitting using a continuous distribution of oscillators reproduces the frequency dependence of the complex dielectric response as well as demonstrates quantitative agreement with a uniform increase in either mode density or polarizability with oxidation in the 5-80 cm(-1) frequency range. Hydration dependence measurements find that a difference in the equilibrium water content for ferri and ferro cytochrome c is not sufficient to account for the large change in terahertz response. The large dielectric increase at terahertz frequencies with oxidation suggests either a significant global softening of the potential and/or a significant increase in polarizability with oxidation.
10aabsorption10abinding10aconformation10adna10adynamics10aheart ferricytochrome-c10amodes10aPhysics10aprotein flexibility10aspectroscopy10astate1 aChen, J., Y.1 aKnab, J., R.1 aCerne, J.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/26300506nas a2200169 4500008004500000020001400045245006500059210006500124260000800189300001400197490000800211653001400219100002000233700001700253700001700270856004900287 2005 Engldsh a0065-772700aProtein dynamics studies using terahertz dielectric response0 aProtein dynamics studies using terahertz dielectric response cAug aU347-U3480 v23010aChemistry1 aMarkelz, A., G.1 aKnab, J., R.1 aChen, J., Y. uhttps://markelz.physics.buffalo.edu/node/23400483nas a2200133 4500008004100000245009500041210006900136260002700205100002000232700001600252700001700268700001500285856004900300 2004 eng d00aMeasuring Protein Flexibility with Terahertz Spectroscopy: Basic Research and Applications0 aMeasuring Protein Flexibility with Terahertz Spectroscopy Basic aSan Diego, CAc06/20041 aMarkelz, A., G.1 aChen, J.-Y.1 aKnab, J., R.1 aMaeder, M. uhttps://markelz.physics.buffalo.edu/node/31100571nas a2200169 4500008004100000245006900041210006900110260005100179300001200230490000900242100002300251700002000274700001900294700001900313700002000332856004900352 2004 eng d00aTagless and universal biosensor for point detection of pathogens0 aTagless and universal biosensor for point detection of pathogens bInternational Society for Optics and Photonics a182-1860 v54111 aMarkelz, Andrea, G1 aKnab, Joseph, R1 aChen, Jing-Yin1 aerne, John, Č1 aCox, William, A uhttps://markelz.physics.buffalo.edu/node/19601843nas 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 aWe 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.
We use terahertz time domain spectroscopy to examine finite size effects on the optical phonon modes in SrTiO3 thin films. In temperature-dependent measurements we find a near absence of mode softening in the TO1 phonon frequency. Furthermore we see an increase in the soft mode frequency with reduced thickness. Both of these results correlate well with the reduced dielectric response observed for nanoscale ferroelectric systems.
10aFerroelectrics10aFinite size10aMode softening10aphonons10aStrontium titanate10aTerahertz1 aWolpert, D1 aKorolev, K1 aSachs, S1 aKnab, J1 aCox, W1 aCerne, J1 aMarkelz, A.G1 aZhao, T1 aRamesh, R1 aMoeckly, B.H uhttps://www.sciencedirect.com/science/article/pii/S138694770300305901941nas a2200373 4500008004100000020001500041245008000056210006900136260003100205300001000236490000600246520087600252653002801128653004401156653002101200653001901221653001901240653002901259653002401288653001801312653001701330653002201347653001201369653001201381653002001393100001601413700001201429700001401441700001601455700001301471700001501484700001901499856004901518 2003 eng d a097284220900aFinite size effects in ferroelectric nanosystems: Absence of mode softening0 aFinite size effects in ferroelectric nanosystems Absence of mode aSan Francisco, CAc02/2003 a76-810 v23 aWe present measurements of the mode softening behavior for PbZr 0.5Ti0.5O3 (PZT(50)) thin films using terahertz time domain spectroscopy (TTDS). The films were grown using pulsed laser deposition (PLD) techniques on silicon substrates to study how reduced size affects the mode softening behavior. At room temperature two modes are observed at 1.1 THz (37 cm-1) and at 2.3 THz (77 cm-1). As the temperature is increased toward Tc we do not see strong mode softening, but rather a spectral weight transfer from the high frequency mode to the low frequency mode. This absence of mode softening is more dramatic than that reported by other investigators[1]. We will discuss the possible sources for this discrepancy. These results suggest a change in lattice dynamics for nanoscale ferroelectric films that may be highly dependent on the sample preparation technique.
10aFerroelectric materials10aFourier Transform Infrared Spectroscopy10aFrequency ranges10aLead compounds10aMode softening10ananostructured materials10aNatural frequencies10aOptical modes10aPermittivity10aphase transitions10aphonons10aRouters10aThermal effects1 aWolpert, D.1 aCox, W.1 aCerne, J.1 aMarkelz, A.1 aZhao, T.1 aRamesh, R.1 aM., Romanowicz uhttps://markelz.physics.buffalo.edu/node/27500445nas 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/31400511nas a2200157 4500008004100000245005900041210005900100260003400159300001200193100001600205700002100221700002000242700002400262700001800286856004900304 2003 eng d00aUltrafast THz spectroscopy of photoactive biomolecules0 aUltrafast THz spectroscopy of photoactive biomolecules aSan Jose, Californiac01/2003 a146-1531 aChen, J.-Y.1 aWhitmire, S., E.1 aMarkelz, A., G.1 aHillebrecht, J., R.1 aBirge, R., R. uhttps://markelz.physics.buffalo.edu/node/31501436nas 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 aWe 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(>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.
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/25801295nas a2200241 4500008004100000020001400041245007000055210006900125260001100194300001400205490000700219520060900226100001400835700001900849700001900868700002000887700002100907700002000928700001600948700002000964700002000984856004901004 1996 eng d a0031-900700aUndressing a collective intersubband excitation in a quantum well0 aUndressing a collective intersubband excitation in a quantum wel cMar 25 a2382-23850 v763 aWe have experimentally measured the 1-2 intersubband absorption in a single 40 nm wide modulation-doped Al0.3Ga0.7As/GaAs square quantum well as a function of frequency, intensity, and charge density. The low-intensity depolarization-shifted absorption occurs near 80 cm(-1) (10 meV or 2.4 THz), nearly 30% higher than the intersubband spacing. At higher intensities, the absorption peak shifts to lower frequencies. Our data are in good agreement with a theory proposed by Zaluzny, which attributes the redshift to a reduction in the depolarization shift as the excited subband becomes populated.
1 aCraig, K.1 aGaldrikian, B.1 aHeyman, J., N.1 aMarkelz, A., G.1 aWilliams, J., B.1 aSherwin, M., S.1 aCampman, K.1 aHopkins, P., F.1 aGossard, A., C. uhttps://markelz.physics.buffalo.edu/node/26501583nas a2200241 4500008004100000020001400041245006200055210006100117260001100178300001200189490000700201520093300208100002001141700001401161700001901175700001501194700001601209700001601225700001501241700002001256700001601276856004901292 1995 eng d a0167-278900aNONLINEAR QUANTUM DYNAMICS IN SEMICONDUCTOR QUANTUM-WELLS0 aNONLINEAR QUANTUM DYNAMICS IN SEMICONDUCTOR QUANTUMWELLS cMay 15 a229-2420 v833 aWe discuss recent measurements of the nonlinear response of electrons in wide quantum wells driven by intense electromagnetic radiation at terahertz frequencies. The theme is the interplay of quantum mechanics, strong periodic driving, the electron-electron interaction and dissipation. We discuss harmonic generation from an asymmetric double quantum well in which the effects of dynamic screening are important. Measurements and theory are found to be in good agreement. We also discuss intensity-dependent absorption in a 400 Angstrom square quantum well. A new nonlinear quantum effect occurs, in which the frequency at which electromagnetic radiation is absorbed shifts to the red with increasing intensity. The preliminary experimental results are in agreement with a theory by Zaluzny, in which the source of the nonlinearity is the self-consistent potential in the Hartree approximation for the electron dynamics.
1 aSherwin, M., S.1 aCraig, K.1 aGaldrikian, B.1 aHeyman, J.1 aMarkelz, A.1 aCampman, K.1 aFafard, S.1 aHopkins, P., F.1 aGossard, A. uhttps://markelz.physics.buffalo.edu/node/27200682nas a2200217 4500008004100000020001400041245011500055210006900170260001100239300001400250490000700264100001400271700002000285700002000305700001800325700001700343700002000360700001900380700001600399856004900415 1995 eng d a0163-182900aQUENCHING OF EXCITONIC QUANTUM-WELL PHOTOLUMINESCENCE BY INTENSE FAR-INFRARED RADIATION - FREE-CARRIER HEATING0 aQUENCHING OF EXCITONIC QUANTUMWELL PHOTOLUMINESCENCE BY INTENSE cFeb 15 a5253-52620 v511 aCerne, J.1 aMarkelz, A., G.1 aSherwin, M., S.1 aAllen, S., J.1 aSundaram, M.1 aGossard, A., C.1 aVanson, P., C.1 aBimberg, D. uhttps://markelz.physics.buffalo.edu/node/26200655nas a2200217 4500008004100000020001400041245008000055210006900135260001100204300001600215490000700231100001800238700002000256700001800276700001400294700002000308700002000328700002000348700002000368856004900388 1995 eng d a0163-182900aRESONANT-ENERGY RELAXATION OF TERAHERTZ-DRIVEN 2-DIMENSIONAL ELECTRON GASES0 aRESONANTENERGY RELAXATION OF TERAHERTZDRIVEN 2DIMENSIONAL ELECTR cJun 15 a18041-180440 v511 aAsmar, N., G.1 aMarkelz, A., G.1 aGwinn, E., G.1 aCerne, J.1 aSherwin, M., S.1 aCampman, K., L.1 aHopkins, P., F.1 aGossard, A., C. uhttps://markelz.physics.buffalo.edu/node/25900500nas a2200169 4500008004100000245003800041210003800079260001300117100002100130700002000151700001600171700002100187700001800208700001700226700002000243856006700263 1995 eng d00aTerahertz grid frequency doublers0 aTerahertz grid frequency doublers bCiteseer1 aChiao, Jung-Chih1 aMarkelz, Andrea1 aLi, Yongjun1 aHacker, Jonathan1 aCrowe, Thomas1 aAllen, James1 aRutledge, David uhttps://www.nrao.edu/meetings/isstt/papers/1995/1995199206.pdf01316nas a2200229 4500008004100000020001400041245006500055210006300120260000800183300001200191490000600203520067700209100001400886700001800900700001900918700002000937700002000957700002000977700002000997700002001017856004901037 1994 eng d a0268-124200aFAR-INFRARED SATURATION SPECTROSCOPY OF A SINGLE SQUARE-WELL0 aFARINFRARED SATURATION SPECTROSCOPY OF A SINGLE SQUAREWELL cMay a627-6290 v93 aWe have performed saturation spectroscopy measurements of the lowest intersubband transition in a single 400 angstrom GaAs/Al0.3Ga0.7As modulation-doped square quantum well. We couple intense tunable far-infrared radiation from the Santa Barbara free electron laser into our sample using an edge-coupling technique and measure absorption as a function of frequency and intensity. Saturation and frequency shifts in the absorption line are clearly observed. We attribute the frequency shifts to reductions in the many-body depolarization shift. From our preliminary measurements, we estimate the intersubband relaxation time to be 600 ps to within a factor of three.
1 aCraig, K.1 aFelix, C., L.1 aHeyman, J., N.1 aMarkelz, A., G.1 aSherwin, M., S.1 aCampman, K., L.1 aHopkins, P., F.1 aGossard, A., C. uhttps://markelz.physics.buffalo.edu/node/26400528nas a2200157 4500008004100000245010600041210006900147260001200216300001400228100001800242700001400260700001800274700001300292700001600305856004900321 1994 eng d00aFrequency Dependence of the Third Order Susceptibility of InAs Quantum Wells at Terahertz Frequencies0 aFrequency Dependence of the Third Order Susceptibility of InAs Q c08/1994 a1193-11961 aMarkelz, A.G.1 aCerne, J.1 aGwinn, E., G.1 aBrar, B.1 aKroemer, H. uhttps://markelz.physics.buffalo.edu/node/31801594nas a2200337 4500008004100000020001400041245009400055210006900149260000800218300001200226490000900238520066100247100001800908700001400926700001800940700001800958700001900976700002100995700001701016700002001033700001501053700001801068700002001086700002001106700002001126700002001146700001301166700001201179700001601191856004901207 1994 eng d a0022-231300aPROBING TERAHERTZ DYNAMICS IN SEMICONDUCTOR NANOSTRUCTURES WITH UCSB FREE-ELECTRON LASERS0 aPROBING TERAHERTZ DYNAMICS IN SEMICONDUCTOR NANOSTRUCTURES WITH cApr a250-2550 v60-13 aThe UCSB free-electron lasers provide kilowatts of continuously tunable radiation from 120 GHz to 4.8 THz. They have the most impact on terahertz science and technology that require a tunable, high power source to explore non-linear dynamics or that sacrifice incident power to recover the linear response of systems with very small cross-section. We describe three experiments that demonstrate the utility of these lasers in experiments on the terahertz dynamics of semiconductor nanostructures: (i) terahertz dynamics of resonant tunneling diodes, (ii) saturation spectroscopy of quantum wells and (iii) photon-assisted tunneling in superlattices.
1 aAllen, S., J.1 aCraig, K.1 aFelix, C., L.1 aGuimaraes, P.1 aHeyman, J., N.1 aKaminski, J., P.1 aKeay, B., J.1 aMarkelz, A., G.1 aRamian, G.1 aScott, J., S.1 aSherwin, M., S.1 aCampman, K., L.1 aHopkins, P., F.1 aGossard, A., C.1 aChow, D.1 aLui, M.1 aLiu, T., Y. uhttps://markelz.physics.buffalo.edu/node/25700717nas a2200241 4500008004100000245008100041210006900122300001000191490000900201100002000210700001800230700001900248700001400267700001800281700001900299700001800318700001800336700002000354700002000374700001700394700001500411856004900426 1993 eng d00aFar-infrared nonlinear response of electrons in semiconductor nanostructures0 aFarinfrared nonlinear response of electrons in semiconductor nan a36-470 v18541 aSherwin, M., S.1 aAsmar, N., G.1 aBewley, W., W.1 aCraig, K.1 aFelix, C., L.1 aGaldrikian, B.1 aGwinn, E., G.1 aMarkelz, A.G.1 aGossard, A., C.1 aHopkins, P., F.1 aSundaram, M.1 aBirnir, B. uhttps://markelz.physics.buffalo.edu/node/320