Raman and far‐infrared study of the lattice vibrations of methanol

Anderson, A.; Andrews, B.; Meiering, Elizabeth M.; Torrie, B. H.

doi:10.1002/jrs.1250190204

Cited by 27 publications

(22 citation statements)

References 16 publications

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“…Spectroscopic studies of pure ice analogs for water and other astrophysically relevant species in the far-IR region were previously reported by Bertie & Whalley (1967), Brown & King (1970), Ferraro et al (1980), Sill et al (1980), Warren (1984Warren ( , 1986, Martonchik et al (1984), Anderson et al (1988), Moore & Hudson (1992), Hudgins et al (1993), Smith et al (1994), A&A 565, A108 (2014) . (c) From Allamandola et al (1992).…”

Section: Introductionmentioning

confidence: 87%

Interstellar ice analogs: band strengths of H₂O, CO₂, CH₃OH, and NH₃in the far-infrared region

Giuliano

Escribano

Martín-Doménech

et al. 2014

A&A

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Context. Whereas observational astronomy now routinely extends to the far-infrared region of the spectrum, systematic laboratory studies are sparse. In particular, experiments on laboratory analogs performed through the years have provided information mainly about the band positions and shapes, while information about the band strengths are scarce and derivable principally from the optical constants. Aims. We measure the band strengths in the far-infrared region of interstellar ice analogs of astrophysically relevant species, such as H 2 O, CO 2 , CH 3 OH, and NH 3 , deposited at low temperature (8-10 K), followed by warm-up, to induce amorphous-crystalline phase transitions when relevant. Methods. The spectra of pure H 2 O, NH 3 , and CH 3 OH ices have been measured in the near-, mid-and far-infrared spectroscopic regions using the Interstellar Astrochemistry Chamber (ISAC) ultra-high-vacuum setup. In addition, far-infrared spectra of NH 3 and CO 2 were measured using a different set-up equipped with a bolometer detector. Band strengths in the far-infrared region were estimated using the corresponding near-and mid-infrared values as a reference. We also performed theoretical calculations of the amorphous and crystalline structures of these molecules using solid state computational programs at density functional theory (DFT) level. Vibrational assignment and mode intensities for these ices were predicted. Results. Infrared band strengths in the 25-500 μm range have been determined for the considered ice samples by direct comparison in the near-and mid-infrared regions. Our values were compared to those we calculated from the literature complex index of refraction. We found differences of a factor of two between the two sets of values. Conclusions. The calculated far-infrared band strengths provide a benchmark for interpreting the observational data from future space telescope missions, allowing the estimation of the ice column densities.

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Section: Introductionmentioning

confidence: 87%

Interstellar ice analogs: band strengths of H₂O, CO₂, CH₃OH, and NH₃in the far-infrared region

Giuliano

Escribano

Martín-Doménech

et al. 2014

A&A

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“…The percentage deviations, A , defined as above, are given for the lattice modes, the internal modes, and the total vibrational spectra of these solids. The assignments of the observed lattice frequencies are tentatively based on the frequency shifts of the deuterated species [20]. However, the calculated eigenvectors show that appreciable mixing occurs between librational and translational modes.…”

Section: T a B L E 8 Optimized Force Constants For Crystalline Methanmentioning

confidence: 98%

Lattice Dynamics of Methanol

Weng

Anderson

1992

Physica Status Solidi (b)

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“…In particular, Bertie & Whalley (1967), Warren (1984), Moore & Hudson (1992), Smith et al (1994), Maldoni et al (1999), and Moore et al (2001) focused mainly on the determination of optical constants and the analysis of the spectral differences between the amorphous and crystalline structures of water ices. Brown & King (1970) and Warren (1986) analyzed pure carbon dioxide ices, Ferraro et al (1980), Sill et al (1980), and Martonchik et al (1984) investigated pure ammonia ices, and Anderson et al (1988) reported spectroscopic data for methanol pure ices.…”

Section: Introductionmentioning

confidence: 99%

Interstellar ice analogs: H₂O ice mixtures with CH₃OH and NH₃in the far-IR region

Giuliano

Martín-Doménech

Escribano

et al. 2016

A&A

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Context. New spectroscopic observations in the far-infrared (IR) range are expected from future planned missions. Although water ice is the only species detected so far in interstellar ices in this range, the presence of ice mixtures requires laboratory characterization of the corresponding spectra. Aims. We present an investigation on far-IR spectra of binary ice mixtures relevant in various astrophysical environments. The foremost goal is to compare the spectroscopic features of the ice mixtures to those of pure ices, and to search for changes in peak frequencies, intensities, and band strengths of the main bands. Methods. Mixtures H 2 O:CH 3 OH and H 2 O:NH 3 of different ratios have been deposited on a diamond substrate at astrophysically relevant conditions. We measured the spectra in the near-and mid-IR regions to derive ice column densities that were subsequently used to calculate the apparent band strengths in the far-IR region. We also designed theoretical models to study these mixtures and to predict their spectra. Results. We recorded spectra of amorphous phases for H 2 O:CH 3 OH mixtures of different compositions, that is 1:1, 3:1, and 10:1 at 8 K, and compared these mixtures to those obtained after warming. This process involves the appearance of new spectral features and changes in band shapes and band strengths. We also compared the spectra to those of the pure species and to theoretical predictions. We measured apparent band strengths for all the observed features. For H 2 O:NH 3 mixtures, the ratios selected were 3:1, 1:1, and 1:3. In this case the spectral variations are even more marked than for the water:methanol samples. Conclusions. Band strengths in the far-IR are missing in astrophysics literature for ice mixtures. The results presented here are valuable for detecting the presence and composition of such mixtures from future space observations in this spectral region.

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Raman and far‐infrared study of the lattice vibrations of methanol

Cited by 27 publications

References 16 publications

Interstellar ice analogs: band strengths of H₂O, CO₂, CH₃OH, and NH₃in the far-infrared region

Interstellar ice analogs: band strengths of H₂O, CO₂, CH₃OH, and NH₃in the far-infrared region

Lattice Dynamics of Methanol

Interstellar ice analogs: H₂O ice mixtures with CH₃OH and NH₃in the far-IR region

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Raman and far‐infrared study of the lattice vibrations of methanol

Cited by 27 publications

References 16 publications

Interstellar ice analogs: band strengths of H2O, CO2, CH3OH, and NH3in the far-infrared region

Interstellar ice analogs: band strengths of H2O, CO2, CH3OH, and NH3in the far-infrared region

Lattice Dynamics of Methanol

Interstellar ice analogs: H2O ice mixtures with CH3OH and NH3in the far-IR region

Contact Info

Product

Resources

About

Interstellar ice analogs: band strengths of H₂O, CO₂, CH₃OH, and NH₃in the far-infrared region

Interstellar ice analogs: band strengths of H₂O, CO₂, CH₃OH, and NH₃in the far-infrared region

Interstellar ice analogs: H₂O ice mixtures with CH₃OH and NH₃in the far-IR region