INTERFEROMETRIC MEASUREMENTS OF THE FAR-INFRARED REFRACTIVE INDEX OF SODIUM FLUORIDE AT LOW TEMPERATURES

1970 ◽  
Author(s):  
Charles M. Randall
Keyword(s):  
Refractive Index ◽  
Sodium Fluoride ◽  
Low Temperatures ◽  
Far Infrared

FAR-INFRARED PROPERTIES OF (TMTSF)2ClO4AT LOW TEMPERATURES

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

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

Single-molecule spectromicroscopy: a route towards sub-wavelength refractometry

2015 ◽  
Vol 184 ◽  
pp. 263-274 ◽  
Author(s):  
T. A. Anikushina ◽  
M. G. Gladush ◽  
A. A. Gorshelev ◽  
A. V. Naumov
Keyword(s):  
Refractive Index ◽  
Single Molecule ◽  
Low Temperatures ◽  
Radiative Lifetime ◽  
Spatially Resolved ◽  
Local Fluctuations ◽  
Novel Approach ◽  
Spectral Linewidth ◽  
Spatial Fluctuations ◽  
Sub Wavelength

We suggest a novel approach for spatially resolved probing of local fluctuations of the refractive index n in solids by means of single-molecule (SM) spectroscopy. It is based on the dependence T1(n) of the effective radiative lifetime T1 of dye centres in solids on n due to the local-field effects. Detection of SM zero-phonon lines at low temperatures gives the values of the SM natural spectral linewidth (which is inversely proportional to T1) and makes it possible to reveal the distribution of the local n values in solids. Here we demonstrate this possibility on the example of amorphous polyethylene and polycrystalline naphthalene doped with terrylene. In particular, we show that the obtained distributions of lifetime limited spectral linewidths of terrylene molecules embedded into these matrices are due to the spatial fluctuations of the refractive index local values.

Refractive index of flames in the far infrared

1973 ◽  
Vol 6 (6) ◽  
pp. 774-780 ◽  
Author(s):  
G Hubner ◽  
A R Jones
Keyword(s):  
Refractive Index ◽  
Far Infrared

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

2019 ◽  
Vol 625 ◽  
pp. A61
Author(s):  
Harald Mutschke ◽  
Pierre Mohr
Keyword(s):  
Low Temperatures ◽  
Optical Constants ◽  
Laboratory Data ◽  
Measurement Data ◽  
Far Infrared ◽  
Absorption Bands ◽  
Lack Of Information ◽  
Temperature Dependences ◽  
Cold Dust ◽  
Infrared Continuum

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.

Refractive Index of GaS in the Far Infrared

1978 ◽  
Vol 87 (1) ◽  
pp. K65-K67 ◽  
Author(s):  
V. Riede ◽  
Hoang Xuan Nguyen ◽  
H. Neumann ◽  
H. Sobotta ◽  
F. Levy
Keyword(s):  
Refractive Index ◽  
Far Infrared

Far-Infrared Spectroscopic Study of Diamond Films

1989 ◽  
Vol 162 ◽  
Author(s):  
A. J. Gatesman ◽  
R. H. Giles ◽  
G. C. Phillips ◽  
J. Waldman ◽  
L. P. Bourget ◽  
...  
Keyword(s):  
Refractive Index ◽  
Spectroscopic Study ◽  
Microwave Plasma ◽  
Complex Refractive Index ◽  
Diamond Films ◽  
Far Infrared ◽  
Infrared Spectroscopic Study ◽  
Infrared Spectroscopic ◽  
Frequency Regime ◽  
Reflectivity Data

High quality polycrystalline diamond films grown on Si substrates by microwave plasma enhanced chemical vapor deposition were characterized in a far-infrared spectroscopic study. The spectroscopic transmissivity data were used to derive a model for the complex refractive index (n – ik) as a function of wavelength in the 10 to 200 cm−1 frequency regime. Similar transmissivity and reflectivity data from samples of varying thickness were used to validate this model. The continuum of measured transmissivity and reflectivity data from 10 to 200 cm−1 were shown to be in excellent agreement with the values calculated from the refractive index model. The films were shown to have low loss in this frequency regime.

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