Laser scattering

Dynamic Behaviors of Molecules at Liquid-Liquid Interfaces Using the Time-Resolved Quasi-Elastic Laser Scattering Method... 

II. QUASI-ELASTIC LASER SCATTERING METHOD A. Capillary Waves... 

Recently, the newly developed time-resolved quasielastic laser scattering (QELS) has been applied to follow the changes in the surface tension of the nonpolarized water nitrobenzene interface upon the injection of cetyltrimethylammonium bromide [34] and sodium dodecyl sulfate [35] around or beyond their critical micelle concentrations. As a matter of fact, the method is based on the determination of the frequency of the thermally excited capillary waves at liquid-liquid interfaces. Since the capillary wave frequency is a function of the surface tension, and the change in the surface tension reflects the ion surface concentration, the QELS method allows us to observe the dynamic changes of the ITIES, such as the formation of monolayers of various surfactants [34]. 

The advancement of the application of lasers in combination with the molecular beam technique has made a great impact in the understanding of primary photodissociation processes. For state-specific detection of small fragments, laser-induced fluorescence, multiphoton ionization, and coherent laser scattering have provided extremely detailed information on the dynamics of photodissociation. Unfortunately, a large number of interesting... 

Komori, S., T. Kanzaki, Y. Murakami, and H. Ueda (1989). Simultaneous measurements of instantaneous concentrations of two species being mixed in a turbulent flow by using a combined laser-induced fluorescence and laser-scattering technique. Physics of Fluids A Fluid Dynamics 1, 349-352. 

One of the earliest detailed diagnostic efforts on sooting of diffusion flames was that of Wagner et al. [86-88], who made laser scattering and extinction measurements, profile determinations of velocity by LDV, and temperature measurements by thermocouples on a Wolfhard-Parker burner using ethene as the fuel. Their results show quite clearly that soot particles are generated near the reaction zone and are convected farther toward the center of the fuel stream as they travel up the flame. The particle number densities and generation rates decline with distance from the flame zone. The soot formation rate appeared to... 

Agglomerated sol particles (10 nm use of ultrasonic waves, laser scattering)... 

Yeh and Keeler 244) extended the method of laser-scattering spectroscopy to probe systems undergoing rapid chemical reactions. They observed the spectral line broadening in light from a singlemode He-Ne laser scattered from multicomponent solutions, as a function of time. The experiment employed a pressure-scanned Fabry-Perrot interferometer and photon counting techniques. 

The distribution of the particle size must be as tight as possible, especially for hard materials such as alumina. A typical particle size distribution curve for alumina used in tungsten slurries is shown in Fig. 2a (data taken by the laser scattering method). However, from time to time the particle size distribution in a slurry may be out of control, so that a long tail will appear at the large particle end (Fig. 2b). These large particles may become a source of CMP scratches. 

Another consideration when choosing a detector is whether it is important to preserve the separated analytes, either for use or for further analysis. Some methods, such as evaporative laser scattering detection and mass spectrometry, destroy the sample during the measurement. Other methods, such as fluorescence or radiochemical detection, may require chemical labeling of the analytes ... 

The elution character of the FFF techniques allows for it to be used in combination with other methods for further on-line or off-line characterization of the analytes (see Figure 12.1). FFF can be hyphenated with selective detection systems like mass spectrometry, multiangle laser scattering and can be combined with different separation techniques in multidimensional modes. In Figure 12.3, the trend in the number of published papers is reported. 

Ward, G., K. M. Cushing, R. D. McPeters, and A. E. S. Green, 1973. Atmospheric aerosol index of refraction and size-altitude distribution from bistatic laser scattering and solar aureole measurements, Appl. Opt., 12, 2582-2592. 

The details of dynamic laser scattering are well described by Berne and Pecora [59] and Chu [60]. 

Aerosol and cloud spectrometer 0.1- to 3.0- xm particles 0.3- to 20.0- xm particles laser scattering inside a cavity in the free air stream 36... 

First, we will describe briefly the biology of secretory cells in general and goblet cells in particular. Next, we will outline our earlier studies on the conformation of mudn networks using dynamic laser scattering. Short discussions on the Donnan swelling properties of the mucin network will bring us to the application of the theory of polymer gel phase transition to explain condensation and decondensation in secretion. 

Laser scattering—focused beam reflectance method, FBRM with high P cell (Clarke and Bishnoi, 2004) Yes P, T, particle formation (min) 1500 psi size range 1-1000 pm stirred Hydrate particle size distribution during growth/decomposition... 

Laser scattering methods have been applied by the groups of Bishnoi and Sloan to measure changes in the hydrate particle size distribution during hydrate... 

Flistorically, the second most important function of the Raman spectrometer was to reject scattered laser radiation. Because the laser scatter from the sample can be many millions of times more intense than the signal and cannot be rejected spatially, the power of the spectrometer to efficiently and... 

More recent light-scattering studies (ref. 26,59,60) of microbubble populations in fresh water, using laser-light sources, have yielded very similar results. For example, Keller s laser-scattered-light technique (ref. 26) provided precise measurements of the size and number of freestream gas nuclei (i.e., long-lived microbubbles) in a cavitation tunnel from microbubble spectra... 

As discussed in more detail in Section 3.2.18, Raman laser scattering detects low concentrations of various gases (Figure 3.17). Finally, the refractive index (RI) fiber-optic probe compares the RI of the process material with that of its prism and measures the reflected light as an indication of process RI. 

Figure 4-12. Fluorescence emission spectra of l-naphthol(NH3) clusters (n — 1-4). The excitation laser is fixed on the 0° bands for n = 1-3. For n = 4, the excitation frequency is fixed at 30,985 cm 1 (laser-scattered light is marked with an asterisk) (from Cheshnovsky and Leutwyler 1988). This clearly shows that the emission spectrum of n = 4 is strongly displaced towards the red characteristic of the naphtholate emission.

Figure 16. A rotational CARS spectrum of O, at one atmosphere pressure. The spectrum is generated using a Nd YAG laser and a scanning-amplified dye laser. Scattered-light discrimination is achieved using a scanning double nonochromator slaved to the dye laser scan.

By contrast, laser scattering methods now permit temperature composition and flow measurements that are both nonintrusive and give very high spatial resolution. These light scattering methods include laser Raman spectroscopy, laser-induced fluorescence, coherent Raman spectroscopy as well as laser velocimetry... 

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