Far-infrared measurements

Frenkel D., van der Elsken J. Anisotropic density fluctuations in argon at different densities far infrared measurements and molecular dynamic calculations, J. Chem. Phys. 67, 4243-53 (1977). 

Na -loess clay, where batch experiments were analyzed by X-ray diffraction and infrared and far-infrared measurements. The adsorption isotherm (Fig. 8.36) shows that loess clay is selective for cesium cations. The raw material contained a large amount of quartz, and the clay material was a mixture of kaolinite and an interstrati-fied iUite-smectite mineral as a result, equilibrium Cs" adsorption data are not consistent with a single site Langmuir model. Cesium adsorption on this particular soil clay occurs by cation exchange on sites with various cesium affinities. At low concentration, far-infrared spechoscopy shows the presence of very selective adsorption sites that correspond to internal collapsed layers. At high concentration, Cs MAS-NMR shows that cesium essentially is adsorbed to external sites that are not very selective. 

For fundamental physical reasons, the attenuation function for any process must vanish as to - °°. This expectation is borne out by far-infrared measurements of ct(u>) for a variety of molecular systems exhibiting a relaxation-type absorption in the microwave and millimeter-wave region (17-23). While H2O as a solute in nonhydrogenbonding solvents also shows this behavior (35), the millimeter-wave and far-infrared spectrum of 0(2.) is complicated by contributions to a (10) due to intermolecular vibrations involving a cluster of H2O molecules (libration and translation), in addition to the high-frequency tail of the relaxation absorption. A heuristic treatment of the general problem (30) makes the relaxation time,... 

Most recently in theoretical approaches to the analysis of NO spectra, Varberg, Stroh and Evenson [133] have used their tunable far-infrared measurements, described in chapter 10, to refine, yet again, the values of the constants. Using results from the A-doublet, rotational and fine-structure spectra of 14NO (v = 0) which have been recorded, the following values of the constants (in MHz) are listed [133] ... 

Table 10.18. Molecular parameters (in MHz) for CH in thev = 0 level of the X2Il ground state, determined from a combination of the far-infrared laser magnetic resonance, field-free microwave measurements [181], andfield-free far-infrared measurements [185]...

IR spectroscopic measurements were performed in the mid and far infrared regions. For mid infrared measurements a Matson Genesis FT-IR spectrometer and the KBr technique (2 mg of sample in 200 mg KBr) were utilized. Far infrared measurements were run on a Bio-Rad-Win-IR FT-IR spectrometer in the 500-100 cm range. In this case HDPE (high density polyethylene) was the matrix material and 128 scans were collected for... 

Recently Brackett, Richards and Caughey (48) have done far infrared measurements on ferrichrome A and report that D =—0.27 cm-1 and A =0.25. 

Far-infrared measurement of vlir the in-plane CCN bending mode. f Torsional frequency. 

When high-quality quantitative optical data are needed for organic conductors that absorb strongly in the infrared [11], the only viable technique consists in measuring the polarized reflectance at normal (or near-normal) incidence from single crystals. The minimum required sample dimension is typically in the order of 1 mm for the visible or near infrared, and 4 mm for the middle- to far-infrared measurements. 

Fig. 10. Optical reflectivity of a SmB single crystal at 4 K and 300 K. The small dashed lines are the extrapolations of tn — 0. The solid and the dotted lines are the lower and upper limit of error of the far infrared measurements. (After Travaglini and Wachter 1984a.)...

It has been established that an interferometer design first proposed by Martin and Puplett [2] is the most effective FT-IR spectrometer configuration for far-infrared measurements, particularly in the wavenumber region lower than 150 cm [3],... 

Redons forming massive stars have been studied extensively by radio observations of Hn regions and masers, far-infrared measurements of the total luminosity, and millimeter mapping of the surrounding molecular gas and dust. These techniques are effective for examining the properties of the most massive stars and the molecular clouds from which they form however, there is little information on the low mass stars which form in the vicinity of massive stars. 

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