Quantitative Anisotropic Analysis of Molecular Orientation in Amorphous N<sub>2</sub>O at 6 K by Infrared Multiple-Angle Incidence Resolution Spectrometry

Hama, Tetsuya; Ishibashi, Atsuki; Kouchi, Akira; Watanabe, Naoki; Shioya, Nobutaka; Shimoaka, Takafumi; Hasegawa, Takeshi

doi:10.1021/acs.jpclett.0c01585

Cited by 7 publications

(17 citation statements)

References 60 publications

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“…7). [33] The copper sample holder was connected to the cold head of a closed-cycle He refrigerator (RDK-101D, Sumitomo Heavy Industries) and installed in the vacuum sample chamber using a bore-through rotary feedthrough (KRP-152, Kitano Seiki). The inner wall of the vacuum chamber was coated with graphite particles (Aerodag G, Henkel Japan) to reduce the noise caused by scattering of IR light in the vacuum chamber.…”

Section: Ir-mairs Measurementsmentioning

confidence: 99%

“…66. [33,34,84] As a single peak for the CO stretching band only appeared in the OP spectra at 1033 cm −1 (Fig. 20B), all CH3OH deposited on the amorphous water surface should interact with the three-coordinated dangling-OH bonds, leading to the strong orientation of CO bonds perpendicular to the surface (Fig.…”

Section: Absorption Cross-section Of Dangling Oh Bondsmentioning

confidence: 99%

“…Hereafter, MAIRS2 is simply referred to as IR-MAIRS. [34] with permission. Copyright 2020 American Chemical Society For IR-MAIRS measurements, the FT-modulated IR light was passed through an angle-controllable linear polarizer comprising a ZnSe wire grid incorporated in the FT-IR spectrometer, and oblique incidence transmission measurements were taken at θ = 45 .…”

Section: Ir-mairs Measurementsmentioning

confidence: 99%

“…[64] A mercury cadmium telluride detector was used to detect the IR light, and the intensity of the transmitted IR light was measured as a single-beam by the FT-IR. [33,34] The accumulation number of the single-beam measurements was 1000 (615 s) for each polarization angle with a resolution of 4 cm À1 . The total measurement time was 4305 s (72 min) for one IR-MAIRS measurement.…”

Section: Ir-mairs Measurementsmentioning

confidence: 99%

“…[25] Recently, we developed an experimental setup for in situ IR-MAIRS under low-temperature, ultrahigh-vacuum conditions. [34,35] This article reviews our recent results for vapor-deposited amorphous water using low-temperature, ultrahigh-vacuum IR-MAIRS. We describe the experimental apparatus and the theoretical framework in detail and present some specific experimental results for vapor-deposited amorphous water, with emphasis on the molecular orientation and absorption cross-section of dangling-OH bonds; that is, the free OH-stretching modes of three-coordinated (one H donor and two H acceptors) and two-coordinated (one H donor and one H acceptor) molecules located at the ice surface (Figure 6).…”

Section: Introductionmentioning

confidence: 99%

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Infrared multiple‐angle incidence resolution spectrometry for vapor‐deposited amorphous water

Nagasawa

Numadate

Hama

2022

J Raman Spectroscopy

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Infrared (IR) multiple-angle incidence resolution spectrometry (IR-MAIRS) is a recently developed spectroscopic technique that combines oblique incidence transmission measurements and chemometrics (multivariate analysis) to obtain both pure in-plane (IP) and outof-plane (OP) vibration spectra for a thin sample. IR-MAIRS is established for analyzing the molecular orientation of organic thin films at atmospheric pressure, but it should also be powerful for the structural characterization of vapor-deposited thin samples prepared in a vacuum. The application of IR-MAIRS to vapor-deposited amorphous water is particularly interesting in the fields of physical and interstellar chemistry, because it is a representative model material for interstellar icy dust grains. We recently developed an experimental setup for in situ IR-MAIRS under low-temperature, ultrahigh-vacuum conditions, which thus facilitates measurements of interstellar ice analogues such as vapor-deposited amorphous water. This review considers the theoretical framework of IR-MAIRS and our recent experimental results for vapor-deposited amorphous water. We present spectroscopic signatures for the perpendicular orientation of dangling OH bonds for three-coordinated water molecules at the surface of amorphous water at 90 K. The absolute absorption cross-section of the three-coordinated dangling OH bonds is quantitatively measured as 1.0 ± 0.2 × 10 −18 cm 2 at 3696 cm −1 . As IR-MAIRS can essentially be conducted using only a Fourier-transform IR spectrometer and an angle-controllable linear polarizer, it is a useful, low-cost, and simple spectroscopic technique for studying laboratory analogues of interstellar ices including vapor-deposited amorphous water.

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Section: Ir-mairs Measurementsmentioning

confidence: 99%

Section: Absorption Cross-section Of Dangling Oh Bondsmentioning

confidence: 99%

Section: Ir-mairs Measurementsmentioning

confidence: 99%

Section: Ir-mairs Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Infrared multiple‐angle incidence resolution spectrometry for vapor‐deposited amorphous water

Nagasawa

Numadate

Hama

2022

J Raman Spectroscopy

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A Spontaneously Electrical State of Matter

2023

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Metrics & MoreArticle Recommendations CONSPECTUS: Molecular deposition on solid surfaces forms crystalline or amorphous/glassy thin solid films. Intermolecular interactions govern the packing and dynamics of these films. The connection between molecular structure and intermolecular interactions is based on understanding electrostatic forces, dispersion forces and hydrogen bonding. Recently, an entire class of dipolar molecular species have demonstrated counterintuitive self-organization such that the dipole moments of individual molecules are oriented in thin films. This leads to the spontaneous generation of polarized molecular films manifesting a polarization charge equivalent to tens to hundreds of volts in strength at the film-vacuum interface, relative to the film-substrate interface. These voltages, and the corresponding electric fields present in such films, result from a collective and spontaneous orientation of molecular dipoles throughout the film during film growth and represent a metastable state of polarized material. The existence of these materials should encourage reconsideration of the importance of solid-state intermolecular electrostatic interactions. This account will detail observations of the spontaneous electric fields in molecular solids, provide insights into the dynamics and structure of molecular materials that the emergence of these electric fields can facilitate, and present a dipole-alignment based meanfield model that reproduces the temperature dependence of the electric field strength. Species as diverse as carbon monoxide, nitrous oxide, freons, simple alcohols, and cis-methyl formate have been demonstrated to spontaneously generate electric fields. We have reported electric fields more than 10 8 V m −1 , have shown how field strength varies with the film deposition temperature, and have reported temperature-dependent Stark shifts observable in both infrared and ultraviolet absorption spectra. The latter has led to the reporting of large Wannier−Mott excitons in wide band gap molecular materials, such as solid carbon monoxide and ammonia. Changes in the field strength with time, at specific temperatures, can be related to the structural dynamics of glassy molecular solids. Measurement of surface potentials is a very sensitive technique by which to observe the rotation and translation of molecular species buried in thin films. This is particularly true for polarized, supercooled molecular glasses, where surface potentials have been used to report on secondary relaxation processes that have hitherto been hidden from measurement.Characterizing spontaneously electric molecular films, and understanding their behavior, requires the inclusion of nonlocal and nonlinear effects. The mean-field model that we present describes the data by connecting the energy of interaction of an average dipole with the mean effective field in the film, where this field is itself a function of the degree of polarization. This feedback loop produces a smooth function with a nonintuitive, discontinuous differ...

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Tuning Molecular Conformations to Enhance Spontaneous Orientation Polarization in Organic Thin Films

Wang

Nakano

Hashizume

et al. 2022

ACS Appl. Mater. Interfaces

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Three isomeric derivatives of 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) bearing ethyl groups on the N-phenyl moieties were synthesized to elucidate the effects of intramolecular interactions on spontaneous orientation polarization (SOP) in thin films. The films of the TPBi derivatives displayed enhanced SOP with a surface potential change of up to 1.8 times that for TPBi, and the p-substituted derivative exhibited the largest potential change reported to date (+141.0 mV/nm). Density functional theory calculations and single-crystal structure analysis suggest that the introduction of the ethyl groups switched the stable molecular conformation from C 1 to C 3 symmetry. Through analysis of the structural anisotropy in the films by spectral ellipsometry and two-dimensional (2D) grazing-incidence wide-angle X-ray scattering, we conclude that the conformational change of the molecules was the major factor underlying the SOP enhancement.

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Quantitative Anisotropic Analysis of Molecular Orientation in Amorphous N₂O at 6 K by Infrared Multiple-Angle Incidence Resolution Spectrometry

Cited by 7 publications

References 60 publications

Infrared multiple‐angle incidence resolution spectrometry for vapor‐deposited amorphous water

Infrared multiple‐angle incidence resolution spectrometry for vapor‐deposited amorphous water

A Spontaneously Electrical State of Matter

Tuning Molecular Conformations to Enhance Spontaneous Orientation Polarization in Organic Thin Films

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Quantitative Anisotropic Analysis of Molecular Orientation in Amorphous N2O at 6 K by Infrared Multiple-Angle Incidence Resolution Spectrometry

Cited by 7 publications

References 60 publications

Infrared multiple‐angle incidence resolution spectrometry for vapor‐deposited amorphous water

Infrared multiple‐angle incidence resolution spectrometry for vapor‐deposited amorphous water

A Spontaneously Electrical State of Matter

Tuning Molecular Conformations to Enhance Spontaneous Orientation Polarization in Organic Thin Films

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Product

Resources

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Quantitative Anisotropic Analysis of Molecular Orientation in Amorphous N₂O at 6 K by Infrared Multiple-Angle Incidence Resolution Spectrometry