Using the C–O stretch to unravel the nature of hydrogen bonding in low-temperature solid methanol–water condensates

Dawes, Anita; Mason, Nigel J.; Fraser, H. J.

doi:10.1039/c5cp05299h

Cited by 31 publications

(42 citation statements)

References 47 publications

(116 reference statements)

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“…There is also an observed redshift in the position of the water bending mode with increasing benzene concentration. Since strong hydrogen bonding is associated with a blueshift in the n 2 bending mode of H 2 O, 21 the observed redshift with respect to pure amorphous solid water confirms that the strength of benzene-water interaction is weaker than that of the water-water hydrogen bonding interaction 24 and is a result of benzene molecules disrupting the water hydrogen bonding network. This is in agreement with results from the VUV spectra (Section 3.1.1) and temperature programmed desorption results of Thrower et al 28 The influence of dilution of benzene in water on the IR bands of benzene is small, resulting only in slight blueshifts in the bands (see Table 2) relative to pure benzene and no visible broadening.…”

Section: Pccp Papermentioning

confidence: 73%

“…We calculated the cross sections of benzene for different concentrations of benzene and water ice mixtures. These values may suffer from errors of up to 20%, not unlike the infrared integrated absorption coefficients, or A-values, for molecular vibrational bands which suffer form uncertainties of up to 30% 21 in the values quoted in the literature. Nevertheless, the results show a significant enhancement of the peak cross section intensity at lower concentrations, tending towards gas phase cross sections of benzene, with a peak gas phase cross section of 270 Mb and 225 Mb, 150 Mb and 75 Mb for 1 : 100, 1 : 10 and 1 : 1 solid phase mixtures of benzene and water respectively, compared with 47 Mb for pure solid benzene.…”

Section: Discussionmentioning

confidence: 99%

“…A detailed description of this set up and general procedures can be found in ref. 21. Briefly, in these experiments absorbance spectra were collected at 1 cm À1 resolution, by averaging 128 scans in the range 4000-800 cm À1 .…”

Section: Experimental Methodsmentioning

confidence: 99%

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Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Dawes

Pascual

Mason

et al. 2018

Phys. Chem. Chem. Phys.

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We present results of a combined vacuum ultraviolet (VUV) and infrared (IR) photoabsorption study of amorphous benzene : water mixtures and layers to investigate the benzene-water interaction in the solid phase. VUV spectra of 1 : 1, 1 : 10 and 1 : 100 benzene : water mixtures at 24 K reveal a concentration dependent shift in the energies of the 1B2u, 1B1u and 1E1u electronic states of benzene. All the electronic bands blueshift from pure amorphous benzene towards gas phase energies with increasing water concentration. IR results reveal a strong dOH-π benzene-water interaction via the dangling OH stretch of water with the delocalised π system of the benzene molecule. Although this interaction influences the electronic states of benzene with the benzene-water interaction causing a redshift in the electronic states from that of the free benzene molecule, the benzene-benzene interaction has a more significant effect on the electronic states of benzene. VUV spectra of benzene and water layers show evidence of non-wetting between benzene and water, characterised by Rayleigh scattering tails at wavelengths greater than 220 nm. Our results also show evidence of benzene-water interaction at the benzene-water interface affecting both the benzene and the water electronic states. Annealing the mixtures and layers of benzene and water show that benzene remains trapped in/under water ice until water desorption near 160 K. These first systematic studies of binary amorphous mixtures in the VUV, supported with complementary IR studies, provide a deeper insight into the influence of intermolecular interactions on intramolecular electronic states with significant implications for our understanding of photochemical processes in more realistic astrochemical environments.

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Section: Pccp Papermentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

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Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Dawes

Pascual

Mason

et al. 2018

Phys. Chem. Chem. Phys.

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“…The products formed in the H 2 CO + H + O 2 experiment are listed in Table 2 along with the corresponding IR signatures that are labeled in Figure 3. Note that the two peaks around 1000 cm −1 are within the frequency range of the C-O stretch of CH 3 OH (Dawes et al 2016). However, these peaks disappear between 195 and 205 K (not shown here), which is a temperature range that is higher than the desorption temperature of CH 3 OH or any species that are positively identified in this study.…”

Section: Formation Of Hcooh Ice By H 2 Co + H + Omentioning

confidence: 92%

Extension of the HCOOH and CO₂ solid-state reaction network during the CO freeze-out stage: inclusion of H₂CO

Qasim

Lamberts

et al. 2019

A&A

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Context. Formic acid (HCOOH) and carbon dioxide (CO 2 ) are simple species that have been detected in the interstellar medium. The solid-state formation pathways of these species under experimental conditions relevant to prestellar cores are primarily based off of weak infrared transitions of the HOCO complex and usually pertain to the H 2 O-rich ice phase, and therefore more experimental data are desired. Aims. Here, we present a new and additional solid-state reaction pathway that can form HCOOH and CO 2 ice at 10 K 'nonenergetically' in the laboratory under conditions related to the "heavy" CO freeze-out stage in dense interstellar clouds, i.e., by the hydrogenation of an H 2 CO:O 2 ice mixture. This pathway is used to piece together the HCOOH and CO 2 formation routes when H 2 CO or CO reacts with H and OH radicals. Methods. Temperature programmed desorption -quadrupole mass spectrometry (TPD-QMS) is used to confirm the formation and pathways of newly synthesized ice species as well as to provide information on relative molecular abundances. Reflection absorption infrared spectroscopy (RAIRS) is additionally employed to characterize reaction products and determine relative molecular abundances.Results. We find that for the conditions investigated in conjunction with theoretical results from the literature, H + HOCO and HCO + OH lead to the formation of HCOOH ice in our experiments. Which reaction is more dominant can be determined if the H + HOCO branching ratio is more constrained by computational simulations, as the HCOOH:CO 2 abundance ratio is experimentally measured to be around 1.8:1. H + HOCO is more likely than OH + CO (without HOCO formation) to form CO 2 . Isotope experiments presented here further validate that H + HOCO is the dominant route for HCOOH ice formation in a CO-rich CO:O 2 ice mixture that is hydrogenated. These data will help in the search and positive identification of HCOOH ice in prestellar cores.

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“…required to calculate these parameters might not be available in some laboratories. In such cases, an analytical method using averaged values has been used [23,32] instead. In order to address the impact of approximated values in the Complex Refractive Index calculation, a statistical analysis was performed.…”

Section: Refractive Index In Infraredmentioning

confidence: 99%

Infrared complex refractive index of N-containing astrophysical ices free of water processed by cosmic-ray simulated in laboratory

Rocha

Pilling

Domaracka

et al. 2020

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Several nitrogen containing species has been unambiguously identified in the Solar System and in the Interstellar Medium. It is believed that such rich inventory of species is a result of the energetic processing of astrophysical ices during all stages of the protostellar evolution. An intrinsic parameter of matter, the complex refractive index, stores all the "chemical memory" triggered by energetic processing, and therefore might be used to probe ice observations in the infrared. In this study, four N-containing ices have been condensed in ultra-high vacuum chamber and processed by heavy ions (O and Ni) with energies between 0.2 and 15.7 MeV at the Grand Accélérateur National d'Ions Lourds (GANIL), in Caen, France. All chemical changes were monitored in situ by a Infrared Absorption Spectroscopy. The complex refractive index was calculated directly from the absorbance spectrum, by using the Lambert-Beer and Kramers-Kroning relations. The values containing the values will be available in a online database: https://www1.univap.br/gaa/nkabs-database/data.htm. As result, other than the database, it was observed that non-polar ices are more destroyed by sputtering than polar ones. Such destruction and chemical evolution leads to variation in the IR albedo of samples addressed in this paper.

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Using the C–O stretch to unravel the nature of hydrogen bonding in low-temperature solid methanol–water condensates

Abstract: The C–O stretch of CH3OH is highly sensitive to the interaction between CH3OH and H2O showing a progressive change in profile as a function of CH3OH/H2O mixing ratio, R.

Cited by 31 publications

References 47 publications

Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Extension of the HCOOH and CO₂ solid-state reaction network during the CO freeze-out stage: inclusion of H₂CO

Infrared complex refractive index of N-containing astrophysical ices free of water processed by cosmic-ray simulated in laboratory

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Using the C–O stretch to unravel the nature of hydrogen bonding in low-temperature solid methanol–water condensates

Abstract: The C–O stretch of CH3OH is highly sensitive to the interaction between CH3OH and H2O showing a progressive change in profile as a function of CH3OH/H2O mixing ratio, R.

Cited by 31 publications

References 47 publications

Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Probing the interaction between solid benzene and water using vacuum ultraviolet and infrared spectroscopy

Extension of the HCOOH and CO2 solid-state reaction network during the CO freeze-out stage: inclusion of H2CO

Infrared complex refractive index of N-containing astrophysical ices free of water processed by cosmic-ray simulated in laboratory

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Extension of the HCOOH and CO₂ solid-state reaction network during the CO freeze-out stage: inclusion of H₂CO