A high-<i>Q</i>easy-to-handle biconcave resonator for acoustic spectrometry of liquids

Polacek, Rüdiger; Kaatze, U.

doi:10.1088/0957-0233/14/7/323

Cited by 15 publications

(11 citation statements)

References 20 publications

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“…[41] At low frequencies (n 12 MHz), where a is small, cavity resonator measurements were performed in which the pathway of interaction between the sample and the sonic field was virtually increased by multiple reflections. [42] Two circular cylindrical resonator cells were employed, one of which (100 kHz n 2 MHz) was provided with concavely shaped glass faces operating as focussing reflectors. The cell was coupled to the electronic circuit by piezoelectric quartz discs attached to the reflectors.…”

Section: Methodsmentioning

confidence: 99%

Ultrasonic Spectrometry of Aqueous Solutions of Alkyl Maltosides: Kinetics of Micelle Formation and Head‐Group Isomerization

Haller

Kaatze

2009

ChemPhysChem

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At frequencies between 100 kHz and 400 MHz, ultrasonic attenuation spectra are measured at 25 degrees C for aqueous solutions of hexyl-, heptyl-, octyl-, nonyl-, and decyl-beta-D-maltopyranoside as well as of decyl-alpha-D-maltopyranoside. The spectra with surfactant concentration c above the relevant critical micelle concentration (cmc) display three relaxation terms with discrete relaxation times. That with a relaxation time between 0.1 and 1.2 micros is due to exchange of monomers between micelles and the suspending phase. It is discussed in the light of the Teubner-Kahlweit-Aniansson-Wall model of the formation/decay kinetics of systems with Gaussian size distribution of micelles. The relaxation parameters are compared to those for solutions of other non-ionic surfactants, such as alkyl monoglycosides and poly(ethylene glycol) monoalkyl ethers. At c < cmc this low-frequency relaxation term is missing and at c approximately = cmc it is broadened, as is characteristic of solutions of oligomeric molecular structures rather than proper micelles. The relaxation terms with relaxation times between 6 and 15 ns and 0.7 and 2.3 ns reveal head-group rotations around glycosidic angles and isomerization of the exocyclic hydroxymethyl group, respectively. These unimolecular reactions are also examined with a view to solutions of alkyl monoglycosides as well as of glucose and maltose.

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Section: Methodsmentioning

confidence: 99%

Ultrasonic Spectrometry of Aqueous Solutions of Alkyl Maltosides: Kinetics of Micelle Formation and Head‐Group Isomerization

Haller

Kaatze

2009

ChemPhysChem

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“…Between 200 kHz and 20 MHz a cavity resonator method, specially designed to small sample loss, was employed. This yields the liquid attenuation coefficient relative to a reference liquid of carefully adjusted sound velocity and density. , A new biconcave reflector resonator (0.2−1.5 MHz) and three biplanar resonator cells (1−20 MHz) were available at the DPI. These cells mainly differ from one another by the fundamental frequency of thickness vibrations (4, 8, and 10 MHz) of the quartz transducer disks used as transmitter and receiver.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of Base-Stacking Interactions and Proton Exchange of 6-Methylpurine Aqueous Solutions

et al. 2004

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Acoustical relaxation properties of aqueous solutions of 6-methylpurine have been studied using broadband ultrasonic spectrometry in the frequency range 0.2-2000 MHz. Excess attenuation with relaxation characteristics was found near the lower limit of the measuring range and also around 100 MHz. The former relaxation process has been assigned to the proton exchange of the ampholytic 6-methylpurine solutions, yielding reasonable rate constants, e.g., 1.1 × 10 3 s -1 dm 3 mol -1 for the ionization and 6 × 10 8 s -1 dm 3 mol -1 for the neutralization at neutral pH. The high frequency relaxation process has been discussed in terms of a sequential and a random isodesmic reaction scheme of stack formation. Similar rate constants have been found for both models, e.g., 5 × 10 9 and 2.5 × 10 8 s -1 for the association and dissociation constant of the sequential reaction scheme, if cooperativity effects are neglected. There are, however, indications of weak cooperativity in the stacking.

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“…Using this method α is actually determined relative to a reference liquid with sound velocity and density matched as close as possible to the sample. We employed three differently constructed cylindrically shaped cavity resonators which were completely filled with the sample. , In order to reduce adverse diffraction effects the cavity faces were concavely shaped. The resonator cells were operated at overlapping frequency ranges using network analyzers to measure the transfer function, including spurious higher-order modes of the cavities.…”

Section: Experimental Sectionmentioning

confidence: 99%

Chain Dynamics of Ethylene Oxide Oligomer Melts. An Ultrasonic Spectroscopy Study

Wald

Kaatze

2014

J. Phys. Chem. B

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Between 0.2 and 2000 MHz, the ultrasonic attenuation spectra of oligomer melts have been measured at 25 °C. The oligomers comprise ethylene glycols with eight different mean degrees [Formula: see text]of polymerization (1 ≤ [Formula: see text] ≤ 13.2), a poly(propylene glycol) ([Formula: see text] = 16.9) and three poly(ethylene glycol) dimethyl ethers (3 ≤ [Formula: see text] ≤ 10.3). The complexity of the ultrasonic spectra increases with [Formula: see text]. The spectra have been analyzed assuming up to four discrete relaxation terms. The relaxation times of these terms are assigned to the first odd modes in the oligomer conformational dynamics and are discussed in the light of the Rouse spring-and-dashpot and the Tobolsky torsional oscillator models of chain variations. The relaxation amplitudes indicate that not only the shear viscosity but also the volume viscosity is involved in ultrasonic relaxation processes. Comparison of relaxation times and shear viscosities for the ethylene glycols with the corresponding data for dimethyl ethers and also n-alkanes reveals significant effects of association.

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A high-Qeasy-to-handle biconcave resonator for acoustic spectrometry of liquids

Cited by 15 publications

References 20 publications

Ultrasonic Spectrometry of Aqueous Solutions of Alkyl Maltosides: Kinetics of Micelle Formation and Head‐Group Isomerization

Ultrasonic Spectrometry of Aqueous Solutions of Alkyl Maltosides: Kinetics of Micelle Formation and Head‐Group Isomerization

Kinetics of Base-Stacking Interactions and Proton Exchange of 6-Methylpurine Aqueous Solutions

Chain Dynamics of Ethylene Oxide Oligomer Melts. An Ultrasonic Spectroscopy Study

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