Low-Frequency Raman Spectra of Nitric Acid Hydrates

Grothe, Hinrich; Myhre, Cathrine Lund; Nielsen, Claus J.

doi:10.1021/jp055521t

Cited by 10 publications

(13 citation statements)

References 41 publications

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“…It is well known that low wavenumber Raman spectra show highly characteristic patterns allowing easy discrimination between different crystals. This fingerprint information was recently employed to clearly distinguish between different solid nitric acid hydrates, including metastable polymorphs 70, 71. At < 400 cm −1 , β‐H 2 CO 3 shows more Raman bands than α‐H 2 CO 3 (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Local structural order in carbonic acid polymorphs: Raman and FT‐IR spectroscopy

Mitterdorfer

Bernard

Klauser

et al. 2011

J Raman Spectroscopy

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Two different polymorphs of carbonic acid, α-and β-H 2 CO 3 , were identified and characterized using infrared spectroscopy (FT-IR) previously. Our attempts to determine the crystal structures of these two polymorphs using powder and thin-film X-ray diffraction techniques have failed so far. Here, we report the Raman spectrum of the α-polymorph, compare it with its FT-IR spectrum and present band assignments in line with our work on the β-polymorph [Angew. Chem. Int. Ed. 48 (2009) 2690-2694]. The Raman spectra also contain information in the wavenumber range ∼90-400 cm −1 , which was not accessible by FT-IR spectroscopy in the previous work. While the α-polymorph shows Raman and IR bands at similar positions over the whole accessible range, the rule of mutual exclusion is obeyed for the β-polymorph. This suggests that there is a center of inversion in the basic building block of β-H 2 CO 3 whereas there is none in α-H 2 CO 3 . Thus, as the basic motif in the crystal structure we suggest the cyclic carbonic acid dimer containing a center of inversion in case of β-H 2 CO 3 and a catemer chain or a sheet-like structure based on carbonic acid dimers not containing a center of inversion in case of α-H 2 CO 3 . This hypothesis is strengthened when comparing Raman active lattice modes at <400 cm −1 with the calculated Raman spectra for different dimers. In particular, the intense band at 192 cm −1 in β-H 2 CO 3 can be explained by the inter-dimer stretching mode of the centrosymmetric RC(OHO) 2 CR entity with R OH. The same entity can be found in gas-phase formic acid (R H) and in β-oxalic acid (R COOH) and produces an intense Raman active band at a very similar wavenumber. The absence of this band in α-H 2 CO 3 confirms that the difference to β-H 2 CO 3 is found in the local coordination environment and/or monomer conformation rather than on the long range.

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Section: Resultsmentioning

confidence: 99%

Local structural order in carbonic acid polymorphs: Raman and FT‐IR spectroscopy

Mitterdorfer

Bernard

Klauser

et al. 2011

J Raman Spectroscopy

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“…20 A recent Raman study showed that different preparation techniques to form the amorphous solid have a minor impact on the later phase composition and phase transition temperatures. 21 The XRD system (Seifert XRD 3000 TT, Germany) hosted the cryostat (Leybold RGD 210, Germany) in its centre. The ESEM system (FEI-Philips XL30 ESEM-FEG) was equipped with a cryo-transfer chamber (Gatan ALTO 2500).…”

Section: Methodsmentioning

confidence: 99%

The crystallization kinetics and morphology of nitric acid trihydrate

Grothe

Tizek

Waller

et al. 2006

Phys. Chem. Chem. Phys.

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Crystallization kinetics of stable and metastable nitric acid trihydrate (NAT) were investigated by time dependent X-ray powder diffraction (XRD) measurements. Kinetic conversion curves were evaluated adopting the Avrami model. The growth and morphology of the respective crystallites were monitored in situ on the cryo-stage of an environmental scanning electron microscope (ESEM) under a partial pressure of nitrogen gas (0.3 Torr, 40 Pa). The results show a close relationship between the presence of ice in the sample and the crystallization mechanism of NAT, which results in different shapes and sizes of NAT crystal particles.

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“…In principle, lowfrequency Raman and/or terahertz spectroscopy for observing lattice mode vibrations would be the most appropriate methods. Recently, low-frequency Raman data have been measured in the lab (Escribano et al, 2007;Grothe et al, 2006a), but far-infrared spectroscopy data -i.e., the THz rangeare still missing. THz observations are impossible from the ground due to water-vapor absorption lines, but might be obtainable directly in the upper atmosphere or from space.…”

Section: Polar Stratospheric Cloudsmentioning

confidence: 99%

Ice structures, patterns, and processes: A view across the icefields

et al. 2012

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We look ahead from the frontiers of research on ice dynamics in its broadest sense; on the structures of ice, the patterns or morphologies it may assume, and the physical and chemical processes in which it is involved. We highlight open questions in the various fields of ice research in nature; ranging from terrestrial and oceanic ice on Earth, to ice in the atmosphere, to ice on other solar system bodies and in interstellar space.

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Low-Frequency Raman Spectra of Nitric Acid Hydrates

Cited by 10 publications

References 41 publications

Local structural order in carbonic acid polymorphs: Raman and FT‐IR spectroscopy

Local structural order in carbonic acid polymorphs: Raman and FT‐IR spectroscopy

The crystallization kinetics and morphology of nitric acid trihydrate

Ice structures, patterns, and processes: A view across the icefields

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