Terahertz response of organic amorphous systems: experimental concerns and perspectives

Šibík, Juraj; Zeitler, J. Axel

doi:10.1080/14786435.2015.1111528

Cited by 29 publications

(30 citation statements)

References 27 publications

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“…The VDOS measured by terahertz spectroscopy is indiscriminate and measures overall contribution, not just the density of states in excess of the Debye level. However, it is important to note that a signature of the actual boson peak can be observed in both absorption coefficient (when plotted divided by the square of frequency) and refractive index as outlined recently [37]. As mentioned in Sec.…”

Section: Vibrational Density Of States and Boson Peakmentioning

confidence: 72%

Direct measurement of molecular mobility and crystallisation of amorphous pharmaceuticals using terahertz spectroscopy

Šibík

Zeitler

2016

Advanced Drug Delivery Reviews

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Despite much effort in the area, no comprehensive understanding of the formation and behaviour of amorphous solids has yet been achieved. This severely limits the industrial application of such materials, including drug delivery where, in principle, amorphous solids have demonstrated their great usefulness in increasing the bioavailability of poorly aqueous soluble active pharmaceutical ingredients. Terahertz time-domain spectroscopy is a relatively novel analytical technique that can be used to measure the fast molecular dynamics of molecules with high accuracy in a non-contact and non-destructive fashion. Over the past decade a number of applications for the characterisation of amorphous drug molecules and formulations have been developed and it has been demonstrated how this technique can be used to determine the onset and strength in molecular mobility that underpins the crystallisation of amorphous drugs. In this review we provide an overview of the history, fundamentals and future perspective of pharmaceutical applications related to the terahertz dynamics of amorphous systems.

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Section: Vibrational Density Of States and Boson Peakmentioning

confidence: 72%

Direct measurement of molecular mobility and crystallisation of amorphous pharmaceuticals using terahertz spectroscopy

Šibík

Zeitler

2016

Advanced Drug Delivery Reviews

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“…We would like to explicitly highlight our notation: in this manuscript we use the symbol T g,α for the temperature where τ α T g,α = 100 s for the dielectric α-relaxation process and T β where τ β T β = 100 s for the JG β -relaxation process. In this manuscript we explicitly do not use the term T g,β but we would like to emphasise that T β ≡ T g,β in the context of our previous work and that of others 7,15,24,26,27,29 .…”

mentioning

confidence: 99%

Insights into the structural dynamics of poly lactic-co-glycolic acid at terahertz frequencies

Shmool

Zeitler

2019

Polym. Chem.

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“…The BP is detectable by inelastic neutron [3][4][5][6][7] or X-ray [8,9] scattering, low-frequency Raman scattering [10][11][12], and low-temperature specific heat [2,13,14]. The BP is also detectable by terahertz-time-domain spectroscopy (THz-TDS); i.e., far infrared (IR) spectroscopy [25][26][27][28][29][30][31][32][33][34], which is not well known. However, recently, THz-TDS is becoming recognized as suitable for the detection of the BP [34].…”

Section: Introductionmentioning

confidence: 99%

Boson peak dynamics of natural polymer starch investigated by terahertz time-domain spectroscopy and low-frequency Raman scattering

Terao

Mori

Fujii

et al. 2018

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Terahertz time-domain spectroscopy and low-frequency Raman scattering were performed on the natural polymer starch to investigate the boson peak (BP) dynamics. In the infrared spectrum, the BP was observed at 0.99THz at the lowest temperature. Compared to the result from a previous study for vitreous glucose, both the frequency of the BP and absorption coefficient show lower values than those of the vitreous glucose. These behaviors originate from the longer correlation length of the medium-range order and lower concentration of hydroxyl groups in the starch. In the Raman spectrum, the BP was observed at 1.1THz at room temperature, although the BP was not observed around room temperature due to the excess wing of the fast relaxation modes in the infrared spectrum. The temperature dependence of ε″(ν) during the heating process and cooling process shows a hysteresis below 230K. During the heating process, kinks were observed at 140K and 230K. These kinks are attributed to the β-relaxation and the β-relaxation, respectively.

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Terahertz response of organic amorphous systems: experimental concerns and perspectives

Cited by 29 publications

References 27 publications

Direct measurement of molecular mobility and crystallisation of amorphous pharmaceuticals using terahertz spectroscopy

Direct measurement of molecular mobility and crystallisation of amorphous pharmaceuticals using terahertz spectroscopy

Insights into the structural dynamics of poly lactic-co-glycolic acid at terahertz frequencies

Boson peak dynamics of natural polymer starch investigated by terahertz time-domain spectroscopy and low-frequency Raman scattering

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