Solid-State Modeling of the Terahertz Spectrum of the High Explosive HMX

Allis, Damian G.; Prokhorova, Darya A.; Korter, Timothy M.

doi:10.1021/jp0554285

Cited by 161 publications

(108 citation statements)

References 28 publications

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“…A possible explanation may be due to the overestimation the energies of the mode at 3.74 THz. It is worth noting that the same phenomenon can be found in many solid-state calculations [8,[33][34][35].…”

Section: )-Coosupporting

confidence: 73%

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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Section: )-Coosupporting

confidence: 73%

First principles investigation of L-alanine in terahertz region

Zheng

Wang

2012

J Biol Phys

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“…This information can provide an extraordinary precise "spectral fingerprint" capable of identification by a series of unique vibrational absorption lines. Such narrow vibrational lines can also provide rigorous input to help guide theoretical modeling 19 and advance the understanding of the vibrational properties of explosive solids.The THz measurement apparatus, method for the recovery of absorbance spectra for the waveguide films, and details of the PPWG have been described previously in Refs. 11 and 14.…”

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confidence: 99%

The underlying terahertz vibrational spectrum of explosives solids

Melinger

Laman

Grischkowsky

2008

Applied Physics Letters

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Using waveguide terahertz time-domain spectroscopy, we demonstrate the measurement of the underlying terahertz vibrational spectrum of the explosive solids hexahydro-1,3,5-trinitro-1,3,5-triazine, and 2,4,6-trinitrotoluene. Each explosive is cast as a polycrystalline thin film with planar ordering on the inner surface of metal parallel plate waveguide. For measurements near 10 K, each explosive reveals a complex spectrum of approximately 20 vibrational modes between 0.5 and 3.5 THz. The explosive films are of sufficient quality to produce vibrational linewidths as much as an order of magnitude sharper compared to conventional terahertz measurements of corresponding pellet samples of explosives. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2949068͔One of the most promising and discussed applications of terahertz ͑THz͒ spectroscopy is the detection and identification of explosive materials.1-3 Previous work has measured the THz absorption of explosive solids, revealing a number of broad features associated with the signature vibrational modes of the material.1,2,4-9 However, the majority of this work has been performed on disordered polycrystalline pellet samples, 1,2,4-8 resulting in inhomogeneous broadening of the absorption features, making their identification more difficult. We have addressed this problem by developing the technique of waveguide terahertz time-domain spectroscopy ͑THz-TDS͒, 10,11 whereby an ordered polycrystalline film is formed on a metal surface and its THz vibrational response is characterized via a parallel plate waveguide ͑PPWG͒. 12,13The planar order of the sample together with the formation of microcrystals of high crystalline quality reduces the inhomogeneous broadening, resulting in considerably sharper and much more identifiable features.11,14-18 Here, we present the application of waveguide THz-TDS to the explosive solids hexahydro-1,3,5-trinitro-1,3,5-triazine ͑RDX͒ and 2,4,6-trinitrotoluene ͑TNT͒, resulting in a dramatic sharpening of the vibrational absorption lines as the films are cooled to near 10 K. The linewidths measured at their full width at half maximum ͑FWHM͒ by waveguide THz-TDS are in some cases more than an order of magnitude sharper than corresponding THz measurements with standard pellets of explosives, and reveal a rich spectrum of approximately 20 narrow vibrational absorption lines between 0.5 and 3.5 THz. This information can provide an extraordinary precise "spectral fingerprint" capable of identification by a series of unique vibrational absorption lines. Such narrow vibrational lines can also provide rigorous input to help guide theoretical modeling 19 and advance the understanding of the vibrational properties of explosive solids.The THz measurement apparatus, method for the recovery of absorbance spectra for the waveguide films, and details of the PPWG have been described previously in Refs. 11 and 14. Prior to film formation, the metal waveguide plates were thoroughly washed with solvent and then plasma cleaned. Thin films of RDX and TNT were fo...

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“…36 This also shows that THz spectroscopy is sensitive to the intermolecular bonding of materials and is a powerful tool for studying the orientation or order of materials. Although theoretical predictions have recently been made by using solid-state density functional theory calculations, 38,40,41 it is still difficult to assign THz peaks by using theoretical models. Moreover, the calculations have not agreed sufficiently well with experimental results, even with small molecules, because the theoretical models do not take complete account of the appropriate crystalline conditions or hydrogen bonding effects.…”

Section: Terahertz Time-domain Spectroscopy (Thz-tds)mentioning

confidence: 99%