Evaporation and Condensation of SiO and SiO<sub>2</sub> Studied by Infrared Spectroscopy

Klevenz, Markus; Wetzel, Steffen; Möller, Martin; Pucci, Annemarie

doi:10.1366/000370210790918346

Cited by 24 publications

(34 citation statements)

References 36 publications

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“…The much weaker structure at ∼713 cm −1 corresponds to the Si stretching mode, a mode with dominating Si displacement 29, sometimes called ‘bending’ mode in the literature. Beyond 1 nm, these peak positions do not shift with film thickness anymore and, accordingly, the IR dielectric function of the evaporated film already resembles that of bulk SiO 12, 14, 30. Thus, in the following discussion, these SiO peak positions will be referred to as bulk frequencies, since, in the limit of long waves, the frequencies of optical vibrations with polarization parallel to the film approach transverse optical (TO) bulk frequencies.…”

Section: Resultsmentioning

confidence: 94%

“…In case of non‐overlapping vibrational bands and strong oscillators, the frequencies of this Berreman‐polariton mode 28, 29, 33, 34 observed in measurements at oblique incidence of p‐polarized light would be equal to longitudinal optical (LO) frequencies. For bulk SiO such simple relation is no more valid, mainly since the oscillators are to weak to produce a negative real part of the dielectric function in the phonon region 12, 30. Additionally, the perpendicular vibrational dipoles give rather low IR signals because of the high dielectric background $\varepsilon _\infty = 3.61$ of SiO 14.…”

Section: Resultsmentioning

confidence: 99%

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Vibrational spectroscopy of SiO on Si(111)

Klevenz

Wetzel

Trieloff

et al. 2010

phys. stat. sol. (b)

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The growth of ultrathin SiO layers on clean Si(111) was observed by in situ infrared spectroscopy under ultra-high vacuum conditions. SiO was deposited by thermal evaporation of SiO powder from a Knudsen cell. A large shift of the SiO main vibrational line, from about 864 cm À1 for sub-monolayer coverage up to the bulk value of SiO at about 982 cm À1 for thicknesses above 10 Å , was observed. The extraordinary low vibrational frequencies for species at the SiO-Si interface corroborate recently published theoretical results for SiO adsorption on Si and for the SiO 2 -Si interface.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Vibrational spectroscopy of SiO on Si(111)

Klevenz

Wetzel

Trieloff

et al. 2010

phys. stat. sol. (b)

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“…It is important to note that already from 1 nm the IR spectral features of the evaporated SiO films no longer change (Klevenz et al 2010b). Accordingly, the IR dielectric function of the evaporated film already resembles that of bulk SiO (Hjortsberg & Granqvist 1980;Tazawa et al 2006;Klevenz et al 2010a). After the in situ measurement the SiO film with the final film thickness auf 57 nm was measured in the FIR.…”

Section: Resultsmentioning

confidence: 99%

“…More recent determinations are given by Tazawa et al (2006). During the course of our laboratory studies on materials of astrophysical interest (Klevenz 2009;Wetzel 2012), the far-infrared optical properties have been determined with high accuracy. We briefly describe the measurements and their results in this paper.…”

Section: Introductionmentioning

confidence: 99%

Laboratory measurement of optical constants of solid SiO and application to circumstellar dust

Wetzel

Klevenz

Gail

et al. 2013

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Context. Silicate minerals belong to the most abundant solids that form in cosmic environments. Their formation requires that a sufficient number of oxygen atoms per silicon atom are freely available. For the standard cosmic element mixture this can usually be taken for granted, but it becomes a problem at the transition from the oxygen-rich chemistry of M-stars to the carbon-rich chemistry of C-stars. In the intermediate type S-stars, most of the oxygen and carbon is consumed by formation of CO and SiO molecules, and left-over oxygen to build SiO 4 -tetrahedrons in solids becomes scarce. Under such conditions SiO molecules from the gas phase may condense into solid SiO. The infrared absorption spectrum of solid SiO differs from that of normal silicates by the absence of Si-O-Si bending modes around 18 μm whereas the absorption band due to Si-O bond stretching modes at about 10 μm is present. Observations show that exactly this particular characteristic can be found in some S-star spectra. Aims. We demonstrate that this observation may be explained by the formation of solid SiO as a major dust component at C/O abundance ratios close to unity. Methods. The infrared absorption properties of solid SiO are determined by laboratory transmission measurements of thin films of SiO produced by vapour deposition on a Si(111) wafer in the range between 100 cm −1 and 5000 cm −1 (2 μm and 100 μm). From the measured spectra the dielectric function of SiO is derived by using a Brendel-oscillator model, particularly suited to the representation of optical properties of amorphous materials. The results are used in model calculations of radiative transfer in circumstellar dust shells with solid SiO dust in order to determine the spectral features due to SiO dust. Results. Comparison of synthetic and observed spectra shows that reasonable agreement is obtained between the main spectral characteristics of emission bands due to solid silicon monoxide and an emission band centred on 10 μm, but without the accompanying 18μm band, observed in some S-stars. We propose that solid SiO is the carrier material of this 10 μm spectral feature.

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“…The majority of the emission occurs between 7 lm and 14 lm with a dominant peak at 8.6 lm, mainly due to the Si-O stretching vibration of the SiO 2 membrane. 32 This is a particularly attractive spectral feature for NDIR systems that target alcohol detection. 33 The experimental measurements are supported by simulation.…”

Section: Resultsmentioning

confidence: 99%

Enhanced infra-red emission from sub-millimeter microelectromechanical systems micro hotplates via inkjet deposited carbon nanoparticles and fullerenes

Luca

Cole

Fasoli

et al. 2013

Journal of Applied Physics

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In this paper, we demonstrate a micro-inkjet printing technique as a reproducible post-process for the deposition of carbon nanoparticles and fullerene adlayers onto fully CMOS compatible micro-electro-mechanical silicon-on-insulator infrared (IR) light sources to enhance their infrared emission. We show experimentally a significant increase in the infrared emission efficiency of the coated emitters. We numerically validate these findings with models suggesting a dominant performance increase for wavelengths <5.5 μm. Here, the bimodal size distribution in the diameter of the carbon nanoparticles, relative to the fullerenes, is an effective mediator towards topologically enhanced emittance of our miniaturised emitters. A 90% improvement in IR emission power density has been shown which we have rationalised with an increase in the mean thickness of the deposited carbon nanoparticle adlayer.

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Evaporation and Condensation of SiO and SiO₂ Studied by Infrared Spectroscopy

Cited by 24 publications

References 36 publications

Vibrational spectroscopy of SiO on Si(111)

Vibrational spectroscopy of SiO on Si(111)

Laboratory measurement of optical constants of solid SiO and application to circumstellar dust

Enhanced infra-red emission from sub-millimeter microelectromechanical systems micro hotplates via inkjet deposited carbon nanoparticles and fullerenes

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Evaporation and Condensation of SiO and SiO2 Studied by Infrared Spectroscopy

Cited by 24 publications

References 36 publications

Vibrational spectroscopy of SiO on Si(111)

Vibrational spectroscopy of SiO on Si(111)

Laboratory measurement of optical constants of solid SiO and application to circumstellar dust

Enhanced infra-red emission from sub-millimeter microelectromechanical systems micro hotplates via inkjet deposited carbon nanoparticles and fullerenes

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Evaporation and Condensation of SiO and SiO₂ Studied by Infrared Spectroscopy