Far-infrared vibrational spectra of all-trans, 9-cis and 13-cis retinal measured by THz time-domain spectroscopy

Walther, Markus; Fischer, Bernd; Schall, M.; Helm, H.; Jepsen, Peter Uhd

doi:10.1016/s0009-2614(00)01271-9

Cited by 307 publications

(155 citation statements)

References 14 publications

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“…Using low-power radiation sources it is simply impossible to penetrate thick layers of water. As a result, studies have been mainly restricted to (bio)molecules embedded in polyethylene, which is transparent in the terahertz region (33), hydrated films of biomolecules (34), and only a few solvents (mainly water and methanol) (35,36). Moreover, to be sure that the surface layers do not influence the results of the measurements, it is important that we probe a sufficiently large volume of the probe.…”

Section: Resultsmentioning

confidence: 99%

Solute-induced retardation of water dynamics probed directly by terahertz spectroscopy

Heugen

Schwaab

Bründermann

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

393

338

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Hydrogen bond rearrangement in water occurs on the picosecond time scale, so relevant experiments must access these times. Here, we show that terahertz spectroscopy can directly investigate hydration layers. By a precise measurement of absorption coefficients between 2.3 THz and 2.9 THz we could determine the size and the characteristics of the hydration shell. The hydration layer around a carbohydrate (lactose) is determined to extend to 5.13 ؎ 0.24 Å from the surface corresponding to Ϸ123 water molecules beyond the first solvation shell. Accompanying molecular modeling calculations support this result and provide a microscopic visualization. Terahertz spectroscopy is shown to probe the collective modes in the water network. The observed increase of the terahertz absorption of the water in the hydration layer is explained in terms of coherent oscillations of the hydration water and solute. Simulations also reveal a slowing down of the hydrogen bond rearrangement dynamics for water molecules near lactose, which occur on the picosecond time scale. The present study demonstrates that terahertz spectroscopy is a sensitive tool to detect solute-induced changes in the water network.hydration water dynamics ͉ molecular dynamics simulations of biomolecules ͉ solvated lactose T he many unusual properties of water combined with its importance as the solvent of life account for its continued study by numerous researchers. Indeed, the properties of water are essential in the behavior of all biological systems. For example, water plays a central role in the folding and function of proteins, and the function of carbohydrates. The dynamics of water surrounding a solute is of fundamental importance in a wide range of processes in solution. In particular, the properties of water molecules near the surface of a biomolecule have been the subject of numerous and sometimes controversial experimental and theoretical studies (1-5). The characteristics and role of this ''biological'' water, with properties that differ considerably from those of bulk water, are still not fully understood (6).The importance of the hydration layer or the biological water is obvious in specific protein processes, such as opening and closing of channels, the kinetics of which has been found to be coupled with the solvent fluctuations (1). Important questions that remain so far unanswered include the following: How does solvation water differ from bulk water, and how large is the solvation layer that can be attributed to solvent water? Simulations suggest the existence of rather rigid water structures around proteins (5) and carbohydrates (7), but experimental studies that characterize the hydration layer are limited. Hydrogen bond rearrangements in water occur on the picosecond time scale (8), so that a detailed understanding of the relevant processes at a molecular level requires experimental techniques that are able to probe the hydration layers on this time scale. However, experimental investigations of fast dynamics of hydration water still remain a ch...

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Section: Resultsmentioning

confidence: 99%

Solute-induced retardation of water dynamics probed directly by terahertz spectroscopy

Heugen

Schwaab

Bründermann

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

393

338

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“…For example, the spectrum of glucose in polycrystalline form measured by THz-TDS is totally different from the spectrum measured in amorphous form, which can be considered as an easy way to identify materials in different states [12]; the spectra among all-trans, 9-cis, and 13-cis retinal are also distinctly different, making the characterization of isomeric crystals efficient [13].…”

Section: Introductionmentioning

confidence: 99%

First principles investigation of L-alanine in terahertz region

Zheng

Wang

2012

J Biol Phys

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Terahertz absorption spectrum (0.5-4.0 THz) of L-alanine in the solid phase was measured by terahertz time-domain spectroscopy at room temperature. Simulations utilizing gaseous-state and solid-state theory were performed to determine the origins of the observed vibrational features. Our calculations showed that the measured features in solidstate materials could be well understood by considering the crystal packing interactions in a solid-state density functional theory calculation. Furthermore, intermolecular vibrations of L-alanine are found to be the dominating contributions to these measured spectral features in the range of 0.5-4.0 THz, except that located at 3.11 THz.

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“…Developed in the 1980s and 1990s [1,2], THz time-domain spectroscopy (THz TDS) has been established as a general spectroscopic technique to study liquids [3], solids [4], gases [5], biomolecules [6,7], aqueous salt solutions [8], nanoparticles [9], semiconductors [10] and plasmas [11]. The covered frequency bandwidth ranges from 3 cm −1 to 140 cm −1 (0.1 THz to 4 THz).…”

Section: Introductionmentioning

confidence: 99%

Uncertainty and Ambiguity in Terahertz Parameter Extraction and Data Analysis

Krüger

Funkner

Bründermann

et al. 2010

J Infrared Milli Terahz Waves

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Phase sensitive measurement techniques, such as THz time-domain spectroscopy or dispersive Fourier transform spectroscopy, are very useful tools to obtain a complete set of optical material parameters. When recording the electric field as a function of time delay between THz and optical pulse, the absorption coefficient and the index of refraction can be extracted. However, the analysis shows ambiguity. Here, we describe an analysis which yields a complete set of mathematical solutions and show how the physically relevant can be deduced. We present a comprehensive mathematical survey for parameter extraction. We have recorded the THz spectra of anthracene and the fatty acid capric acid as examples for weakly absorbing solid samples, and an ionic liquid as an example for a strongly absorbing liquid sample. Finally, we discuss the uncertainty of the obtained optical parameters using error propagation of the Fourier transformation with a simple model and a rigorous mathematical procedure.The final publication is available at link.springer.com:http://dx

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Far-infrared vibrational spectra of all-trans, 9-cis and 13-cis retinal measured by THz time-domain spectroscopy

Cited by 307 publications

References 14 publications

Solute-induced retardation of water dynamics probed directly by terahertz spectroscopy

Solute-induced retardation of water dynamics probed directly by terahertz spectroscopy

First principles investigation of L-alanine in terahertz region

Uncertainty and Ambiguity in Terahertz Parameter Extraction and Data Analysis

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