The Experts below are selected from a list of 154719 Experts worldwide ranked by ideXlab platform
Peter Hamm - One of the best experts on this subject based on the ideXlab platform.
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surface enhanced 2d attenuated total reflectance IR Spectroscopy for surface sensitive ultrafast dynamics
International Conference on Ultrafast Phenomena (2016) paper UTh1A.1, 2016Co-Authors: Jan Philip Kraack, Peter HammAbstract:2D ATR IR Spectroscopy is introduced as a new and versatile spectroscopic method for studying ultrafast vibrational dynamics at solid-liquid interfaces. Investigations are reported comprising organic monolayers, surface-enhanced IR Spectroscopy and spectro-electrochemistry.
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Surface Enhancement in Ultrafast 2D ATR IR Spectroscopy at the Metal-Liquid Interface
The Journal of Physical Chemistry C, 2016Co-Authors: Jan Philip Kraack, Andres Kaech, Peter HammAbstract:We investigate surface enhancement in two-dimensional attenuated total reflectance infrared (2D ATR IR) Spectroscopy from organic monolayers (MLs) at metal–liquid interfaces. We consider MLs from both aromatic and aliphatic organic samples equipped with nitrile and azide functional groups, both of which are widely used as local vibrational probes in ultrafast Spectroscopy. Polarization-dependent 2D ATR IR Spectroscopy indicates the excitation of local hot spots formed between gold (Au) nanoparticles as the dominant origin of signal enhancement. The highest enhancement factors (∼50) are observed in the case of aromatic nitrile MLs, whereas modest values (
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compact implementation of fourier transform two dimensional IR Spectroscopy without phase ambiguity
Journal of The Optical Society of America B-optical Physics, 2011Co-Authors: Jan Helbing, Peter HammAbstract:We describe an optimized setup for two-dimensional (2D) IR Spectroscopy, which can be implemented at low additional cost and with standard optics in any laboratory equipped for femtosecond mid-IR Spectroscopy. An interferometer produces a paIR of intense pump pulses, whose interferogram is simultaneously recorded and dIRectly yields the relative phase needed for the calculation of absorptive 2D spectra. We analyze different sampling methods based on a realistic noise model and introduce fast population time modulation as an alternative to the use of choppers in the suppression of scatter. Signal levels are compared to those of a photon-echo setup.
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Difference 2D-IR Spectroscopy on the chromophore in bacteriorhodopsin
Springer Series in Chemical Physics, 2009Co-Authors: Esben Ravn Andresen, Jan Helbing, Peter HammAbstract:Difference two-dimensional-infrared (2D-IR) Spectroscopy has been employed to measure the 2D-IR spectrum of the C=C and C=ND chromophore bands in bacteriorhodopsin, demonstrating that couplings between individual bands in a mid-size protein can be measured.
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Transient 2D-IR Spectroscopy of thiopeptide isomerization.
The journal of physical chemistry. B, 2008Co-Authors: Valentina Cervetto, Peter Hamm, Jan HelbingAbstract:Transient 2D-IR spectra have been recorded during the photoreaction of the thioxopeptide Boc-Ala-Gly(═S)-Ala-Aib-OMe. We demonstrate the potential of transient 2D-IR Spectroscopy to resolve vibrati...
Jan Helbing - One of the best experts on this subject based on the ideXlab platform.
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compact implementation of fourier transform two dimensional IR Spectroscopy without phase ambiguity
Journal of The Optical Society of America B-optical Physics, 2011Co-Authors: Jan Helbing, Peter HammAbstract:We describe an optimized setup for two-dimensional (2D) IR Spectroscopy, which can be implemented at low additional cost and with standard optics in any laboratory equipped for femtosecond mid-IR Spectroscopy. An interferometer produces a paIR of intense pump pulses, whose interferogram is simultaneously recorded and dIRectly yields the relative phase needed for the calculation of absorptive 2D spectra. We analyze different sampling methods based on a realistic noise model and introduce fast population time modulation as an alternative to the use of choppers in the suppression of scatter. Signal levels are compared to those of a photon-echo setup.
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Difference 2D-IR Spectroscopy on the chromophore in bacteriorhodopsin
Springer Series in Chemical Physics, 2009Co-Authors: Esben Ravn Andresen, Jan Helbing, Peter HammAbstract:Difference two-dimensional-infrared (2D-IR) Spectroscopy has been employed to measure the 2D-IR spectrum of the C=C and C=ND chromophore bands in bacteriorhodopsin, demonstrating that couplings between individual bands in a mid-size protein can be measured.
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Transient 2D-IR Spectroscopy of thiopeptide isomerization.
The journal of physical chemistry. B, 2008Co-Authors: Valentina Cervetto, Peter Hamm, Jan HelbingAbstract:Transient 2D-IR spectra have been recorded during the photoreaction of the thioxopeptide Boc-Ala-Gly(═S)-Ala-Aib-OMe. We demonstrate the potential of transient 2D-IR Spectroscopy to resolve vibrati...
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2D-IR Spectroscopy of transient species
Springer Series in Chemical Physics, 2005Co-Authors: Jens Bredenbeck, Jan Helbing, Peter HammAbstract:Transient two-dimensional infrared Spectroscopy (T2D-IR) extends 2D-IR Spectroscopy to the non-equilibrium regime. We demonstrate different types of T2D-IR experiments for a charge transfer state of [Re(CH3-bpy(CO)3Cl], including the vibrational analogue of NMR-exchange Spectroscopy.
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Two-dimensional IR Spectroscopy of transient species
2004Co-Authors: Jens Bredenbeck, Jan Helbing, Peter HammAbstract:Transient two-dimensional infrared Spectroscopy (T2D-IR) extends 2D-IR Spectroscopy to the non-equilibrium regime. We demonstrate different types of T2D-IR experiments for a charge transfer state of [Re(CH)3-bpy(CO)3Cl], including the vibrational analogue of NMR-exchange Spectroscopy.
Neil T. Hunt - One of the best experts on this subject based on the ideXlab platform.
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Differentiation of bacterial spores via 2D-IR Spectroscopy.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2020Co-Authors: Barbara Procacci, Samantha H. Rutherford, Gregory M. Greetham, Michael Towrie, Anthony W. Parker, Camilla V. Robinson, Christopher R. Howle, Neil T. HuntAbstract:Abstract Ultrafast 2D-IR Spectroscopy is a powerful tool for understanding the Spectroscopy and dynamics of biological molecules in the solution phase. A number of recent studies have begun to explore the utility of the information-rich 2D-IR spectra for analytical applications. Here, we report the application of ultrafast 2D-IR Spectroscopy for the detection and classification of bacterial spores. 2D-IR spectra of Bacillus atrophaeus and Bacillus thuringiensis spores as dry films on CaF2 windows were obtained. The sporulated nature of the bacteria was confIRmed using 2D-IR diagonal and off-diagonal peaks arising from the calcium dipicolinate CaDP·3H2O biomarker for sporulation. Distinctive peaks, in the protein amide I region of the spectrum were used to differentiate the two types of spore. The identified marker modes demonstrate the potential for the use of 2D-IR methods as a dIRect means of spore classification. We discuss these new results in perspective with the current state of analytical 2D-IR measurements, showing that the potential exists to apply 2D-IR Spectroscopy to detect the spores on surfaces and in suspensions as well as in dry films. The results demonstrate how applying 2D-IR screening methodologies to spores would enable the creation of a library of spectra for classification purposes.
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Measuring proteins in H2O with 2D-IR Spectroscopy
Chemical science, 2019Co-Authors: Samantha Hume, Gregory M. Greetham, Michael Towrie, Anthony W. Parker, Gordon Hithell, Paul M. Donaldson, Matthew J. Baker, Neil T. HuntAbstract:The amide I infrared band of proteins is highly sensitive to secondary structure, but studies under physiological conditions are prevented by strong, overlapping water absorptions, motivating the widespread use of deuterated solutions. H/D exchange raises fundamental questions regarding the impact of increased mass on protein dynamics, while deuteration is impractical for biomedical or commercial applications of protein IR Spectroscopy. We show that 2D-IR Spectroscopy can avoid this problem because the 2D-IR amide I signature of proteins dominates that of water even at sub-millimolar protein concentrations. Using equine blood serum as a test system, we investigate the significant implications of being able to measure the Spectroscopy and dynamics of proteins in water, demonstrating relevance in areas ranging from fundamental science to the clinic. Measurements of vibrational relaxation dynamics of serum proteins reveals that deuteration slows down the rate of amide I vibrational relaxation by >10%, indicating a dynamic impact of isotopic exchange in some proteins. The unique link between protein secondary structure and 2D-IR amide I lineshape allows differentiation of signals due to albumin and globulin protein fractions in serum leading to measurements of the biomedically-important albumin to globulin ratio (AGR) with an accuracy of ±4% across a clinically-relevant range. Furthermore, we demonstrate that 2D-IR Spectroscopy enables differentiation of the structurally similar globulin proteins IgG, IgA and IgM, opening up a straightforward spectroscopic approach to measuring levels of serum proteins that are currently only accessible via biomedical laboratory testing.
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Applications of 2D-IR Spectroscopy to Probe the Structural Dynamics of DNA
Frontiers and Advances in Molecular Spectroscopy, 2018Co-Authors: Gordon Hithell, Lennart A. I. Ramakers, Glenn A. Burley, Neil T. HuntAbstract:Abstract Ultrafast two-dimensional infrared (2D-IR) Spectroscopy is a powerful probe of the structural and vibrational dynamics of proteins and enzymes in the solution phase. Until recently, relatively few applications of 2D-IR to DNA had been reported, but this is beginning to change rapidly, showing that the vibrational modes of DNA are sensitive reporters of base paIRing and stacking and allowing site-specific probing of the nature of the complex interactions of the DNA macromolecule with its solvent envIRonment. Most recently, 2D-IR Spectroscopy has been used to probe the minor-groove ligand binding mechanism and reveals the melting of double-stranded DNA in real time, offering the potential for 2D-IR to provide mechanistic insight into the behavior of this most fundamental of biological molecules in the solution phase. The experimental methods used to obtain 2D-IR spectra are fIRst described along with a discussion of the 2D-IR spectral features relevant to DNA studies before a review of the current state of the art of 2D-IR Spectroscopy applications to DNA is presented.
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2D-IR Spectroscopy: ultrafast insights into biomolecule structure and function
Chemical Society Reviews, 2009Co-Authors: Neil T. HuntAbstract:Ultrafast 2D-IR Spectroscopy is rapidly becoming a valuable tool for examining the relationship between structure and function of biomolecules. The unique combination of molecular-level structural information and ultrafast time resolution gives previously inaccessible insights relating to the rapid structural fluctuations, vibrational dynamics and solvent-solute interactions of proteins, all of which have important implications for the biological function of these species. In this tutorial review, the method and development of ultrafast 2D-IR Spectroscopy is discussed, including an introduction to the two main experimental approaches, double resonance and photon echo 2D-IR, and the extension of the technique to non-equilibrium or transient 2D-IR measurements. The scope of the new information available through 2D-IR Spectroscopy is then demonstrated by reference to the current state of the art of 2D-IR studies of molecules of biological interest.
Michael Towrie - One of the best experts on this subject based on the ideXlab platform.
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Differentiation of bacterial spores via 2D-IR Spectroscopy.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2020Co-Authors: Barbara Procacci, Samantha H. Rutherford, Gregory M. Greetham, Michael Towrie, Anthony W. Parker, Camilla V. Robinson, Christopher R. Howle, Neil T. HuntAbstract:Abstract Ultrafast 2D-IR Spectroscopy is a powerful tool for understanding the Spectroscopy and dynamics of biological molecules in the solution phase. A number of recent studies have begun to explore the utility of the information-rich 2D-IR spectra for analytical applications. Here, we report the application of ultrafast 2D-IR Spectroscopy for the detection and classification of bacterial spores. 2D-IR spectra of Bacillus atrophaeus and Bacillus thuringiensis spores as dry films on CaF2 windows were obtained. The sporulated nature of the bacteria was confIRmed using 2D-IR diagonal and off-diagonal peaks arising from the calcium dipicolinate CaDP·3H2O biomarker for sporulation. Distinctive peaks, in the protein amide I region of the spectrum were used to differentiate the two types of spore. The identified marker modes demonstrate the potential for the use of 2D-IR methods as a dIRect means of spore classification. We discuss these new results in perspective with the current state of analytical 2D-IR measurements, showing that the potential exists to apply 2D-IR Spectroscopy to detect the spores on surfaces and in suspensions as well as in dry films. The results demonstrate how applying 2D-IR screening methodologies to spores would enable the creation of a library of spectra for classification purposes.
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Measuring proteins in H2O with 2D-IR Spectroscopy
Chemical science, 2019Co-Authors: Samantha Hume, Gregory M. Greetham, Michael Towrie, Anthony W. Parker, Gordon Hithell, Paul M. Donaldson, Matthew J. Baker, Neil T. HuntAbstract:The amide I infrared band of proteins is highly sensitive to secondary structure, but studies under physiological conditions are prevented by strong, overlapping water absorptions, motivating the widespread use of deuterated solutions. H/D exchange raises fundamental questions regarding the impact of increased mass on protein dynamics, while deuteration is impractical for biomedical or commercial applications of protein IR Spectroscopy. We show that 2D-IR Spectroscopy can avoid this problem because the 2D-IR amide I signature of proteins dominates that of water even at sub-millimolar protein concentrations. Using equine blood serum as a test system, we investigate the significant implications of being able to measure the Spectroscopy and dynamics of proteins in water, demonstrating relevance in areas ranging from fundamental science to the clinic. Measurements of vibrational relaxation dynamics of serum proteins reveals that deuteration slows down the rate of amide I vibrational relaxation by >10%, indicating a dynamic impact of isotopic exchange in some proteins. The unique link between protein secondary structure and 2D-IR amide I lineshape allows differentiation of signals due to albumin and globulin protein fractions in serum leading to measurements of the biomedically-important albumin to globulin ratio (AGR) with an accuracy of ±4% across a clinically-relevant range. Furthermore, we demonstrate that 2D-IR Spectroscopy enables differentiation of the structurally similar globulin proteins IgG, IgA and IgM, opening up a straightforward spectroscopic approach to measuring levels of serum proteins that are currently only accessible via biomedical laboratory testing.
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Waveguide-enhanced 2D-IR Spectroscopy in the gas phase
Optics letters, 2013Co-Authors: Gregory M. Greetham, Ian P. Clark, Damien Weidmann, Michael N. R. Ashfold, Andrew J. Orr-ewing, Michael TowrieAbstract:A method for obtaining high-quality 2D-IR spectra of gas-phase samples is presented. Time-resolved IR absorption Spectroscopy techniques, such as 2D-IR Spectroscopy, often requIRe that beams are focused into the sample. This limits the exploitable overlapped path length through samples to a few millimeters. To cIRcumvent this limitation, 2D-IR experiments have been performed within a hollow waveguide. This has enabled acquisition of 2D-IR spectra of low-concentration gas-phase samples, with more than an order of magnitude signal enhancement compared with the equivalent experiment in free space. The technique is demonstrated by application to the 2D-IR Spectroscopy of IRon pentacarbonyl.
Gregory M. Greetham - One of the best experts on this subject based on the ideXlab platform.
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Differentiation of bacterial spores via 2D-IR Spectroscopy.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2020Co-Authors: Barbara Procacci, Samantha H. Rutherford, Gregory M. Greetham, Michael Towrie, Anthony W. Parker, Camilla V. Robinson, Christopher R. Howle, Neil T. HuntAbstract:Abstract Ultrafast 2D-IR Spectroscopy is a powerful tool for understanding the Spectroscopy and dynamics of biological molecules in the solution phase. A number of recent studies have begun to explore the utility of the information-rich 2D-IR spectra for analytical applications. Here, we report the application of ultrafast 2D-IR Spectroscopy for the detection and classification of bacterial spores. 2D-IR spectra of Bacillus atrophaeus and Bacillus thuringiensis spores as dry films on CaF2 windows were obtained. The sporulated nature of the bacteria was confIRmed using 2D-IR diagonal and off-diagonal peaks arising from the calcium dipicolinate CaDP·3H2O biomarker for sporulation. Distinctive peaks, in the protein amide I region of the spectrum were used to differentiate the two types of spore. The identified marker modes demonstrate the potential for the use of 2D-IR methods as a dIRect means of spore classification. We discuss these new results in perspective with the current state of analytical 2D-IR measurements, showing that the potential exists to apply 2D-IR Spectroscopy to detect the spores on surfaces and in suspensions as well as in dry films. The results demonstrate how applying 2D-IR screening methodologies to spores would enable the creation of a library of spectra for classification purposes.
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Measuring proteins in H2O with 2D-IR Spectroscopy
Chemical science, 2019Co-Authors: Samantha Hume, Gregory M. Greetham, Michael Towrie, Anthony W. Parker, Gordon Hithell, Paul M. Donaldson, Matthew J. Baker, Neil T. HuntAbstract:The amide I infrared band of proteins is highly sensitive to secondary structure, but studies under physiological conditions are prevented by strong, overlapping water absorptions, motivating the widespread use of deuterated solutions. H/D exchange raises fundamental questions regarding the impact of increased mass on protein dynamics, while deuteration is impractical for biomedical or commercial applications of protein IR Spectroscopy. We show that 2D-IR Spectroscopy can avoid this problem because the 2D-IR amide I signature of proteins dominates that of water even at sub-millimolar protein concentrations. Using equine blood serum as a test system, we investigate the significant implications of being able to measure the Spectroscopy and dynamics of proteins in water, demonstrating relevance in areas ranging from fundamental science to the clinic. Measurements of vibrational relaxation dynamics of serum proteins reveals that deuteration slows down the rate of amide I vibrational relaxation by >10%, indicating a dynamic impact of isotopic exchange in some proteins. The unique link between protein secondary structure and 2D-IR amide I lineshape allows differentiation of signals due to albumin and globulin protein fractions in serum leading to measurements of the biomedically-important albumin to globulin ratio (AGR) with an accuracy of ±4% across a clinically-relevant range. Furthermore, we demonstrate that 2D-IR Spectroscopy enables differentiation of the structurally similar globulin proteins IgG, IgA and IgM, opening up a straightforward spectroscopic approach to measuring levels of serum proteins that are currently only accessible via biomedical laboratory testing.
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Waveguide-enhanced 2D-IR Spectroscopy in the gas phase
Optics letters, 2013Co-Authors: Gregory M. Greetham, Ian P. Clark, Damien Weidmann, Michael N. R. Ashfold, Andrew J. Orr-ewing, Michael TowrieAbstract:A method for obtaining high-quality 2D-IR spectra of gas-phase samples is presented. Time-resolved IR absorption Spectroscopy techniques, such as 2D-IR Spectroscopy, often requIRe that beams are focused into the sample. This limits the exploitable overlapped path length through samples to a few millimeters. To cIRcumvent this limitation, 2D-IR experiments have been performed within a hollow waveguide. This has enabled acquisition of 2D-IR spectra of low-concentration gas-phase samples, with more than an order of magnitude signal enhancement compared with the equivalent experiment in free space. The technique is demonstrated by application to the 2D-IR Spectroscopy of IRon pentacarbonyl.
