Ultrasonic attenuation spectroscopy

Sensors for particle size characterization used for crystallization include ultrasound attenuation measurement/ " laser diffraction/ and laser backscatteiing/ commercially called focused beam reflectance measurement (FBRM). Ultrasonic attenuation spectroscopy has been used to monitor the crystallization process parameters such as the crystal size distribution, concentration, and the onset of nucleation during batch crystallization of L-glutamic acid/ Off-line laser diffraction has been used to measure the crystal size distribution in the development of the crystallization process for a pharmaceutical intermediate/ ... 

Li, M. Wilkinson, D. Patchigolla, K. Mougin, P. Roberts, K.J. Tweedie, R. On-line crystallization process parameter measurements using ultrasonic attenuation spectroscopy. Crystal Growth Design 2004, 4 (5), 955-963. 

This paper focuses on the application of two particle sizing methods, laser diffraction spectroscopy and ultrasonic attenuation spectroscopy, to the characterization of suspensions of filmed powders. 

Acoustic Methods Ultrasonic attenuation spectroscopy is a method well suited to measuring the PSD of colloids, dispersions, slurries, and emulsions (Fig. 21-15). The basic concept is to measure the frequency-dependent attenuation or velocity of the ultrasound as it passes through the sample. The attenuation includes... 

Figure 5 Particle size for a 10% com oil-in-water emulsion measured by ultrasonic attenuation spectroscopy (Malvern Ultrasizer, Malvern, UK) and a static light-scattering measurement (LA-900, Horiba Instmments, Irvine, CA) of a dilution (O < 0.05%) of the same emulsion. Both techniques give comparable results, but ultrasound is reliable in more realistic, concentrated emulsions.

Fig. 2.18 Principle of ultrasonic attenuation spectroscopy (left) and kinds of particle-wave interaction in sound fields (right)...

P. Mougin, D. Wilkinson, K.J. Roberts, R. Tweedie, Characterization of particle size and its distribution during the crystallization of organic fine chemical products as measured in situ using ultrasonic attenuation spectroscopy. J. Acoust. Soc. Am. 109(1), 274-282 (2001). doi 10. 1121/1.1331113... 

On-line particle sizing by ultrasonic (acoustic attenuation) spectroscopy was developed for use during batch crystallization processes.14 Crystallization of the alpha polymorph of (l) -glutamic acid from aqueous solution was monitored by continuously pumping the crystallizing solution through an on-line ultrasonic spectrometer. The method enabled measurement of the crystal size distribution and solid concentration throughout the... 

Acoustic attenuation spectroscopy (ultrasonic) AAS Acoustic wave interaction 0.025->100... 

Ultrasonic Spectroscopy. Information on size distribution maybe obtained from the attenuation of sound waves traveling through a particle dispersion. Two distinct approaches are being used to extract particle size data from the attenuation spectmm an empirical approach based on the Bouguer-Lambert-Beerlaw (63) and a more fundamental or first-principle approach (64—66). The first-principle approach implies that no caHbration is required, but certain physical constants of both phases, ie, speed of sound, density, thermal coefficient of expansion, heat capacity, thermal conductivity. 

Tsai, C. S. and Lee, C. C. (1987). Nondestructive imaging and characterization of electronic materials and devices using scanning acoustic microscopy. In Pattern recognition and acoustical imaging (ed. L. A. Ferrari). SPIE 768,260-6. [ 110,202] Tsukahara, Y. and Ohira, K. (1989). Attenuation measurements in polymer films and coatings by ultrasonic spectroscopy. Ultrasonics Int. 89, 924-9. [204]... 

The ring-opening metathesis polymerization of dicyclopentadiene was monitored by ultrasonic spectroscopy.16 The thermoset poly(dicyclopentadiene) is formed by ringopening and cross-linking in a reaction injection molding system. A reaction cell with a plastic window was constructed for use with pulse echo ultrasonic spectroscopy. Realtime measurements of density, longitudinal velocity, acoustic modulus and attenuation were monitored. Reaction kinetics were successfully determined and monitored using this technique. 

Ultrasonic Sciences (www. ultrasonic-scientific. com) Attenuation and velocity spectroscopy-resonance Materials characterization No Yes... 

The attenuation and velocity of acoustic energy in polymers are very different from those in other materials due to their unique viscoelastic properties. The use of ultrasonic techniques, such as acoustic spectroscopy, for the characterization of polymers has been demonstrated [47,48]. For AW devices, the propagation of an acoustic wave in a substrate causes an oscillating displacement of particles on the substrate surface. For a medium in intimate contact with the substrate, the horizontal component of this motion produces a shearing force. In such cases, there can be sufficient interaction between the acoustic wave and the adjacent medium to perturb the properties of the wave. For polymeric materials, attenuation and velocity of the acoustic wave will be affected by changes in the viscoelastic behavior of the polymer. 

Part II of the book deals with lesser known aspects of US for the analytical chemists such as its use as an energy source for detection purposes. Thus, ultrasound-based detection techniques viz. US spectrometry in its various modes including ultrasound attenuation, ultrasonic velocity, resonant ultrasound, laser-generated, ultrasound reflection and acoustic wave impedance spectroscopies) are dealt with in Chapter 9. Finally, Chapter 10 is devoted to seleoted applioations of US spectrometry — mostly non-analytical applications from whioh, however, analytical chemists can derive new, interesting analytical uses for ultrasound-based deteotion techniques. 

---