Exploiting Photoionization Reflectron Time-of-Flight Mass Spectrometry to Explore Molecular Mass Growth Processes to Complex Organic Molecules in Interstellar and Solar System Ice Analogs

Turner, Andrew M.; Kaiser, Ralf I.

doi:10.1021/acs.accounts.0c00584

Cited by 50 publications

(72 citation statements)

References 69 publications

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“…After the exposure of the PH 3 -N 2 ices to energetic electrons at 5 K, the irradiated ices were sublimed at a rate of 1 K min −1 to 300 K while probing the subliming molecules in the gas phase via PI-ReTOF-MS ( 28 ). This methodology denotes an extraordinary technique of detecting gas phase molecules isomer-selectively exploiting soft photoionization on the basis of their distinct adiabatic IEs through methodically tuning the photon energies (PEs) above and below the IE of the isomer of interest.…”

Section: Resultsmentioning

confidence: 99%

Formation of the elusive tetrahedral P ₃ N molecule

2022

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The tetrahedral 1,2,3-triphospha-4-azatricyclo [1.1.0.0 2,4 ] butane (P 3 N) molecule—an isovalent species of phosphorus (P 4 )—was prepared in low-temperature (5 K) phosphine-nitrogen ices and was identified in the gas phase through isomer-selective, tunable, soft photoionization reflectron time-of-flight mass spectrometry. Theoretical calculations reveal that the substitution of a single phosphorus atom by nitrogen in the P 4 molecule results in enhanced spherical aromaticity while simultaneously increasing the strain energy from 74 to 195 kJ mol −1 . In P 3 N, the P─P bond is shortened compared to those in P 4 by 3.6 pm, while the P─N─P bond angle of 73.0° is larger by 13.0° compared to the P─P─P bond angle of 60.0° in P 4 . The identification of tetrahedral P 3 N enhances our fundamental understanding of the chemical bonding, electronic structure, and stability of binary, interpnictide tetrahedral molecules and reveals a universal route to prepare ring strained cage molecules in extreme environments.

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Section: Resultsmentioning

confidence: 99%

Formation of the elusive tetrahedral P ₃ N molecule

2022

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“…[24] Here, exposing ices of pure acetaldehyde -the simplest aldehyde with an α-hydrogen atom-as a representative example, we investigated the galactic cosmic ray (GCR)-induced enolization of aldehydes in interstellar ices using energetic electrons as a proxy of GCRs. [25] The vinyl alcohol formed in these experiments was distinguished from its aldehyde isomer by photoionization reflectron time-of-flight mass spectrometry (PI-ReToF-MS), [26] which allowed to exclusively ionize and detect vinyl alcohol. Mechanistic pathways were extracted by exploiting mixtures of acetaldehyde and acetaldehyde-d 4 at cryogenic temperatures in the solid state (5 K) thus revealing the role of hydrogen-bonded dimers of acetaldehyde in the formation of vinyl alcohol.…”

Section: Introductionmentioning

confidence: 99%

Interstellar Enolization‐Acetaldehyde (CH₃CHO) and Vinyl Alcohol (H₂CCH(OH)) as a Case Study

Kleimeier

Kaiser

2021

ChemPhysChem

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Owing to the unique conditions in cold molecular clouds, enols—the thermodynamically less stable tautomers of aldehydes and ketones—do not undergo tautomerization to their more stable tautomers in the gas phase because they cannot overcome tautomerization barriers at the low temperatures. Laboratory studies of interstellar analog ices have demonstrated the formation of several keto–enol tautomer pairs in astrochemically relevant ice mixtures over the last years. However, so far only one of them, acetaldehyde−vinyl alcohol, has been detected in deep space. Due to their reactivity with electrophiles, enols can play a crucial role in our understanding of the molecular complexity in the interstellar medium and in comets and meteorites. To study the enolization of aldehydes in interstellar ices by interaction with galactic cosmic rays (GCRs), we irradiated acetaldehyde ices with energetic electrons as proxies of secondary electrons generated in the track of GCRs while penetrating interstellar ices. The results indicate that GCRs can induce enolization of acetaldehyde and that intra‐ as well as intermolecular processes are relevant. Therefore, enols should be ubiquitous in the interstellar medium and could be searched for using radio telescopes such as ALMA. Once enols are detected and abundances are established, they can serve as tracers for the non‐equilibrium chemistry in interstellar ices thus eventually constraining fundamental reaction mechanisms deep inside interstellar ices.

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“…The molecular survey of W51e1/e2 provided an inventory of gas-phase molecules, as compiled in Figures 7 and 8. It is important not only to detect these molecules via microwave spectroscopy, but also to discuss potential formation pathways, particularly of complex organic molecules (COMs) and hydrocarbons, along with nitriles, from the bottom up (Abplanalp et al 2016a;Turner & Kaiser 2020). These formation routes are discussed in this section, first in the context of laboratory experiments elucidating the synthesis of organic molecules in interstellar ices in cold molecular clouds, followed by sublimation into the gas phase in the hot core stage, as studied through surface science experiments (Figure 7).…”

Section: Molecule Formation Mechanismsmentioning

confidence: 99%

“…Once formed inside the ices at 10 K, the transition from the cold molecular cloud to a starforming region leads to the sublimation of the newly formed molecules from the ices into the gas phase, driven by temperature increases of the ices by up to 300 K. The gasphase studies exploit crossed molecular beam experiments where the reactants collide under single-collision conditions; this approach guarantees that only primary reaction products are identified (Mebel & Kaiser 2015). To present versatile reaction mechanisms, it is important to rearrange the astronomical inventory of the molecules detected toward W51e1/e2 (Table 2; Figures 7 and 8) according to their chemical functional groups, since the synthesis of molecules with identical functional groups is driven by identical and hence versatile reaction mechanisms (Kaiser & Balucani 2001;Kaiser 2002;Kaiser & Mebel 2002Mebel & Kaiser 2015;Abplanalp et al 2016a;Turner & Kaiser 2020). In Section 4.1, we discuss laboratory experiments exploiting isomer-selective, tunable photoionization; these studies have revealed that COMs, as compiled in Figure 7, can be formed within interstellar ices at 10 K, followed by the sublimation of the new species into the gas phase when the cold cloud transitions to a star-forming region.…”

Section: Molecule Formation Mechanismsmentioning

confidence: 99%

Spectral-line Survey of the Region of Massive Star Formation W51e1/e2 in the 4 mm Wavelength Range

Kalenskii

Kaiser

Bergman

et al. 2022

ApJ

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We present the results of a spectral-line survey of the W51e1/e2 star-forming region at 68–88 GHz. 79 molecules and their isotopologues were detected, from simple diatomic or triatomic molecules, such as SO, SiO, and CCH, to complex organic compounds, such as CH3OCH3 or CH3COCH3. A number of lines that are absent from the Lovas list of molecular lines observed in space were detected, and most of these were identified. A significant number of the detected molecules are typical for hot cores. These include the neutral molecules HCOOCH3, CH3CH2OH, and CH3COCH3, which are currently believed to exist in the gas phase only in hot cores and shock-heated gas. In addition, vibrationally excited C4H and HC3N lines with upper-level energies of several hundred Kelvins were found. Such lines can arise only in hot gas with temperatures on the order of 100 K or higher. Apart from neutral molecules, various molecular ions were also detected. Some of these (HC18O+, H13CO+, and HCS+) usually exist in molecular clouds with high visual extinctions. Potential formation pathways of complex organic molecules and hydrocarbons, along with nitriles, are considered. These formation routes are first discussed in the context of laboratory experiments elucidating the synthesis of organic molecules in interstellar ices in cold molecular clouds, followed by sublimation into the gas phase in the hot core stage. Thereafter, we discuss the predominant formation of hydrocarbons and their nitriles in the gas phase through bimolecular neutral–neutral reactions.

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Exploiting Photoionization Reflectron Time-of-Flight Mass Spectrometry to Explore Molecular Mass Growth Processes to Complex Organic Molecules in Interstellar and Solar System Ice Analogs

Cited by 50 publications

References 69 publications

Formation of the elusive tetrahedral P ₃ N molecule

Formation of the elusive tetrahedral P ₃ N molecule

Interstellar Enolization‐Acetaldehyde (CH₃CHO) and Vinyl Alcohol (H₂CCH(OH)) as a Case Study

Spectral-line Survey of the Region of Massive Star Formation W51e1/e2 in the 4 mm Wavelength Range

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Exploiting Photoionization Reflectron Time-of-Flight Mass Spectrometry to Explore Molecular Mass Growth Processes to Complex Organic Molecules in Interstellar and Solar System Ice Analogs

Cited by 50 publications

References 69 publications

Formation of the elusive tetrahedral P 3 N molecule

Formation of the elusive tetrahedral P 3 N molecule

Interstellar Enolization‐Acetaldehyde (CH3CHO) and Vinyl Alcohol (H2CCH(OH)) as a Case Study

Spectral-line Survey of the Region of Massive Star Formation W51e1/e2 in the 4 mm Wavelength Range

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Product

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Formation of the elusive tetrahedral P ₃ N molecule

Formation of the elusive tetrahedral P ₃ N molecule

Interstellar Enolization‐Acetaldehyde (CH₃CHO) and Vinyl Alcohol (H₂CCH(OH)) as a Case Study