High-resolution ultrasonic spectroscopy

As stated above, US secondary responses are obtained under speoific conditions such as resonance, are derived from primary responses suoh as impedanoe or are a fraction of the overall primary response e.g. absorption, refleotion). Measurements made under resonanoe conditions are the basis for resonance ultrasonic spectroscopy (RUS), also known as high-resolution ultrasonic spectroscopy — the latter name was given by the leading manufacturer of RUS instruments. The importanoe of this teohnique warrants disoussion of its basic principles below. 

DUR Durme, K. van, Delellio, L., Kudryashov, E., Buckin, V., and Mele, B. van, Exploration of high-resolution ultrasonic spectroscopy as an analytical tool to study demixing and remixing in poly(Y-isopropyl aciylamide)/water solutions, J. Polym. Sci. PartB Polym. Phys., 43, 1283, 2005. 

Kucerik, J., D. Smejkalova, H. Cechlovska, and M. Pekar. 2007. New insights into aggregation and conformational behaviour of humic substances Application of high resolution ultrasonic spectroscopy. Organic Geochemistry 38, no. 12 2098-2110. 

Table 1.41. Main characteristics of high-resolution ultrasonic spectroscopy...

In summary, the great potential of ultrasonic spectroscopy is the reliable characterisation of concentrated suspensions. For well-defined colloidal suspensions it may be used for fast off-hne determinations of the size distribution, although the resolution is rather coarse. Its application to process monitoring is principally possible, yet this may require the development of an appropriate data analysis for the specific process. However, a sufficiently high sensitivity to relevant changes in product quahty or process performance can outweigh this additional effort. 

To elucidate the shear-banding scenario in wornolike micelles, different velocimetry techniques with high spatial resolution, typically between 10 and 50 pm, such as nuclear magnetic resonance (NMR) velocimetry, particle image velocimetry (PIV), particle tracking velocimetry (PTV), photon correlation spectroscopy (DLS), and ultrasonic velocimetry (USV) have been developed. All provide the velocity component along the flow direction taken from a one-dimensional slice across the gap. For details on these techniques, the reader is invited to refer to [245,246]. 

---