Hugh H. Richardson

FT‐IR spectra of vacuum deposited clathrate hydrates of oxirane H2S, THF, and ethane

An ability to prepare clathrate hydrates using low temperature–high vacuum techniques, originally demonstrated for the hydrate of oxirane (Bertie and Devlin), has been extended to include the structure I hydrate of H2S, the mixed structure I hydrate of oxirane and ethane, as well as the structure II simple hydrate of THF and the double hydrates of THF with oxirane and H2S. The crystalline clathrate films (∼6 μ) have been formed either by annealing amorphous host–guest deposits at ∼130 K, epitaxial growth at 110 K (oxirane and mixed ethane–oxirane), or direct deposition at 150 K (THF and its double clathrates). Use of the epitaxial approach at ∼100 K has permitted the formation of the oxirane clathrate hydrate containing intact isolated D2O molecules. This has permitted the FT–IR observation of the ν3–ν1 doublet in the O–D stretching region (2455 and 2380 cm−1 at 100 K) with the values, after correction for Fermi resonance, suggesting a splitting from intramolecular coupling of ∼56 cm−1 (2455 vs 2399 cm−1)...

Mobile Bjerrum defects: A criterion for ice‐like crystal growth

There has recently been a substantial increase in information on low‐temperature phase transformations of ice and ice‐like substances along with a rapid increse in molecular level information on the defect structure and activity of this subset of hydrogen‐bonded solids. These data, some quantitative and some qualitative in nature, are examined from the viewpoint that the phase transformation mechanism depends on the availability of mobile orientational defects (Bjerrum L defects) within the new phase. Some of the data that seem particularly apt for establishing any dependence of the phase transformation on the presence of mobile L defects within the new phase, reflect a strong correlation between transformation rates/temperature and the availability of mobile L defects. One possible inference is that the integrity of a growing phase can be maintained only if defects responsible for orientational mobility at the interface can ultimately achieve equilibrium through recombination. The implications of such a ...

FT‐IR investigation of proton transfer in irradiated ice at 90 K in the absence of mobile bjerrum defects

Samples of cubic and amorphous ice containing isolated D2O molecules have been prepared using established methods. Radiolysis with 1.7 MeV electrons at 90 K has been observed to convert the D2O in H2O cubic ice to primarily coupled HOD pairs (HOD)2 rather than isolated HOD. Based on the assumption that radiolysis produces an abundance of mobile protons but relatively few mobile orientational defects this result was predictable, i.e., the motion of protons through D2O sites converts the D2O to coupled (HOD)2, while extensive conversion of (HOD)2 units to isolated HOD requires the passage of orientational defects. Thus, the vanishingly small amount of isolated HOD formed during irradiation has been interpreted as evidence that no significant number of mobile orientational defects are produced by radiolysis. The ability to observe (HOD)2 as a dominant spectroscopic species has added to the credibility of an earlier thermal study of the kinetics of proton motion in ice that was dependent on the quantitative d...

Quantitative Analysis of a Binary Mixture by Fourier Transform Infrared Photoacoustic Spectroscopy

The isotopic shift of the v2 NO3−1 absorption of mixtures of K15NO3 and K14NO3 at 800 and 825 cm−1 has been used to demonstrate that Fourier transform infrared photoacoustic spectroscopy is a technique which is useful for quantitative analysis of solid mixtures.

Fourier-Transformed Infrared Photoacoustic Spectroscopy, the Technique and its Applications

An FTIR spectroneter head has been used to provide broad band nodulated light which is used to excite a sample in a photoacoustic cell. The photoacoustic interferogram can be transformed to provide a photoacoustic infrared absorbance spectrur.1 of the sample. This technique is conpleinentary to ATE! and diffuse reflectance. The metho6 is non-destructive and requires essentially no sarriple preparztion. The resulting spectra i ndicate that the method is sensitive to both the sample particulate size and the reflectivity of the sample. Preliminary data is presented indicating the drmatic effects of particulate size on the spectra. Some infornation on the quantitative use of this method down to the parts-per-thousa nd range is also discussed.