scholarly journals Far-infrared continuum absorption of forsterite and enstatite at low temperatures

2019 ◽  
Vol 625 ◽  
pp. A61
Author(s):  
Harald Mutschke ◽  
Pierre Mohr

Context. The far-infrared continuum opacity of cold dust is an important quantity for the study of debris disks in planetary systems and of protoplanetary disks. Forsterite and enstatite are considered to be the most abundant crystalline dust species in such environments. Aims. The optical constants of these minerals at wavelengths above 80 μm, which govern the opacity, and their temperature dependence are poorly known. Our aim is to fill in this lack of information with new laboratory data. Methods. We present spectroscopic transmission measurements on forsterite and enstatite single crystals of up to 10 mm thickness at wavelengths between 45 and 500 μm and for temperatures down to 10 K. We compare our results to literature data originating from powder transmission and from reflection spectroscopy. Results. The imaginary parts of the refractive indices calculated from the measurements show very strong temperature dependences, which to that extent are not seen in reflection-based data or in powder measurement data. The temperature dependences can be described by a simple theoretical model taking the contributions of single-phonon absorption and phonon difference processes into account. We also observe, for the first time, enstatite absorption bands at 87.5 μm and 116.6 μm wavelengths. Conclusions. The single-crystal optical constants of forsterite and enstatite predict an extremely small submillimeter opacity of crystalline silicate dust at low temperatures, which would make these particles almost invisible in the thermal radiation of cold dust. Thus, it is important to understand why absorption measurements with mineral powders resulted in much higher opacity values.

2013 ◽  
Vol 65 (10) ◽  
pp. 1139-1143 ◽  
Author(s):  
H. Mutschke ◽  
S. Zeidler ◽  
H. Chihara

1991 ◽  
Vol 69 (11) ◽  
pp. 1745-1751 ◽  
Author(s):  
Yoshitaka Fujita ◽  
Tetsuhiko Ohba ◽  
Shun-Ichi Ikawa

The far-infrared optical constants of liquid acetonitrile, carbon disulfide, and carbon tetrachloride were determined from transmission measurements with a synchrotron radiation source at the Institute for Molecular Science (Okazaki). The small size of the synchrotron radiation source was of benefit to measurements of transmittances that were suited for an analysis based on an optical theory. From the transmittances of liquid acetonitrile at temperatures ranging from 238 to 343 K, both the absorption coefficients and the refractive indices were obtained by using the subtractive Kramers–Kronig relation proposed by Jones and co-workers. The dipole moment of liquid acetonitrile calculated from the optical constants, 4.5 ± 0.1 D, is nearly independent of temperature. The spectra of carbon disulfide and carbon tetrachloride were measured at pressures in the ranges 1–1800 bar and 1–1100 bar, respectively. The absorption coefficients were obtained from the transmittances by neglecting the dispersion of the refractive indices. The zeroth and second moments of the collision-induced absorption bands were obtained as a function of pressure, after resolving the overlap of intramolecular vibrational bands. Key words: far-infrared, optical constants, pressure, liquid, synchrotron radiation source.


1983 ◽  
Vol 44 (C3) ◽  
pp. C3-867-C3-872 ◽  
Author(s):  
H. K. Ng ◽  
T. Timusk ◽  
K. Bechgaard

1985 ◽  
Vol 6 (4) ◽  
pp. 287-306 ◽  
Author(s):  
S. Ikawa ◽  
T. Ohba ◽  
S. Tanaka ◽  
Y. Morimoto ◽  
K. Fukushi ◽  
...  

CERUCUK ◽  
2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Cindy Nitasari ◽  
Markawie Markawie

In Tanah Grogot district, precisely on the KM 6 road which is the city boundary roads of Tanah Grogot City-Lolo Kuaro it has an important role as the only access for road users. Because at the side of the roads does not have a drainage channel, resulting in water overflowing and the seepage flowed on the surface, causing a landslide. The length of the landslides is 50 meters, with a width of 5.5 meters and the highest height is 9.6 meters. The result of this landslide is very disturbing for the road users. The delivery of goods and services can not be accommodated properly. Therefore, it is expected that this path must be handled properly, so the road can be functioning again safely and comfortably. How to handle this problem is by making a design of retaining walls construction which is safe in form of sheet pile.The planning for this anchored sheet pile begins with analyzing the secondary data in form of data sondir, laboratory data, and topographic measurement data. This then followed by the calculation of the forces acting on the sheet pile, the calculation of moments in the sheet pile, the calculation of the carrying capacity of the pile on the anchor, capacity calculations for the mast against a lateral load, and the slope stability analysis using GeoStudio2007 application. After that designing the sheet pile construction, tierod, the pile, planning the budget, and makes the Detail Engineering Design (DED).From the planning, the profile of concrete sheet pile obtained is CCSP W-500-A-1000 with a total length of the sheet pile is 12.2 meters. On tierod using dimensions of 6.32 m long with a diameter of 5 cm. On the pile is using a steel pipe with a diameter of 40 cm which penetrated into 10 m depth. For the stability of the slope with the reinforcement of piles obtained SF = 5.5> 1.25, which can be said as safe.Keywords:  designing sheet pile, anchored sheet pile, steel pipe piles.


2019 ◽  
Vol 61 (5) ◽  
pp. 888
Author(s):  
Е.А. Раджабов ◽  
В.А. Козловский

The processes of electron transfer from a divalent lanthanide acceptor (Eu, Sm, Yb) to a trivalent lanthanide donor (Nd, Sm, Dy, Tm, Yb) and reverse thermal transfer are studied in barium fluoride crystals. Electron phototransfer at room temperatures is accompanied by a counter-movement of the charge-compensating interstitial fluorine. In the process of photobleaching at low temperatures, the divalent lanthanide donor turns out to be near the interstitial fluorine, which causes its 4f-5d absorption bands to shift to the red. The magnitude of the shift increases with decreasing size of the lanthanide in the series (Nd, Sm, Dy, Tm, Yb). Detailed mechanisms of photo and thermal electron transfer between heterogeneous lanthanides in BaF2 crystals are analyzed.


2015 ◽  
Vol 579 ◽  
pp. A60 ◽  
Author(s):  
R. Schneider ◽  
S. Bianchi ◽  
R. Valiante ◽  
G. Risaliti ◽  
S. Salvadori

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