Laser-doppler spectroscopy

Precedents for EM distributions of similar width to those depicted in Figure 7 have been generated for other material systems by a measurement technique that is capable of directly resolving the distribution laser-doppler spectroscopy(29). While the present measurement technique provides no information about the frequency function for the distribution, a physical basis does exist for the creation of such a distribution within a powder comprised of nominally identical particles as well as within the two component mixtures. 

This chapter is concerned with experimental investigations of the dynamics of the dissociation of polyatomic neutral molecules carried out by the technique of laser Doppler spectroscopy, in bulk and under crossed-beam condition. Photodissociation is a basic process in the interaction of light with molecules, of interest in itself as an elementary molecular process and also with respect to a variety of applications in different fields. The interest has increased considerably in recent years, first, because the experimental investigation of photodissociation is rapidly advancing by the use of the laser, and second, because the laser makes possible to achieve photodissociation, state, and isotope selectively, by new excitation mechanisms. These are, aside from the common one-photon absorption, stepwise... 

Laser Doppler spectroscopy has been used to measure the statistically averaged properties of swimming cell populations. A bibliography on this topic can be found in Ascoli et al. (1978a). 

Optical laser Doppler spectroscopy/imaging volume-averaged blood flow... 

Uzgiris, E. E., Laser Doppler Spectroscopy Applications to Cell and Particle... 

The brief history, operation principle, and applications of the above-mentioned techniques are described in this chapter. There are several other measuring techniques, such as the fluorometry technique. Scanning Acoustic Microscopy, Laser Doppler Vibrometer, and Time-of-flight Secondary Ion Mass Spectroscopy, which are successfully applied in micro/nanotribology, are introduced in this chapter, too. 

Some very important surface properties of solids can be properly characterized only by certain wet chemical techniques, some of which are currently under rapid improvement. Studies of adsorption from solution allow determination of the surface density of adsorbing sites, and the characterization of the surface forces involved (the energy of dispersion forces, the strength of acidic or basic sites and the surface density of coul-ombic charge). Adsorption studies can now be extended with some newer spectroscopic tools (Fourier-transform infra-red spectroscopy, laser Raman spectroscopy, and solid NMR spectroscopy), as well as convenient modern versions of older techniques (Doppler electrophoresis, flow microcalorimetry, and automated ellipsometry). 

The methods described in this book are primarily concerned with the measurement of the microstructure of complex fluids subject to the application of external, orienting fields. In the case of flow, it is also of interest to measure the kinematics of the fluid motion. This chapter describes two experimental techniques that can be used for this purpose laser Doppler velocimetry for the measurement of fluid velocities, and dynamic light scattering (or photon correlation spectroscopy) for the determination of velocity gradients. 

Wieman, C. and Hansch, T.W. (1976). Doppler-free laser polarization spectroscopy, Phys. Rev. Lett., 36, 1170-1173. 

This Doppler width can be avoided by typical sub-Doppler laser spectroscopy techniques. Laser saturation spectroscopy with a resolution close to the natural line width was used for a test of Special Relativity at the ESR. For such sub-Doppler resolution one must also take into account the small additional broadening and shift arising from the angle 0 between laser beam and ion beam in the Doppler formula. At an interaction length of 10 meters and more, angles are easily controlled to be better than 1 mrad. This limits a possible shift, which enters by... 

PLGA microspheres. Methods to measure the zeta potential of microspheres are laser doppler anemometry [105] and photon correlation spectroscopy [110]. 

Dynamic light scattering (photon correlation spectroscopy, PCS) Laser doppler velocimetry... 

The original Acoustosizer used a single frequency whereas a later development has a range of 13 frequencies between 0.3 and 13 MHz. This allows the measurement of the dynamic mobility spectrum and the determination of the zeta potential and particle size. In order to invert the mobility spectrum into a size distribution a log-normal distribution of particle size is assumed. A comparison with photon correlation spectroscopy for determining particle size and laser Doppler anemometry for particle charge eonfirmed the results using ACS [266]. These and additional sedimentation measurements confirmed that changes in particle size and zeta potential due to dilution effects are likely to occur in aqueous and non-stabilized systems. 

Successful engine design tailors the cylinder aerodynamics to achieve the desired burn rate. In recent times, this has been aided by laser diagnostics and computational fluid dynamics. In-cylinder diagnostic techniques for production engines include the use of rapid response pressure transducers, ion gauges as markers of flame progress, laser doppler velocimetry and emission spectroscopy. These have been reviewed historically by Witze [103]. The two zone analysis of Chun and Heywood [104] enables the net heat release rate to be derived from the pressure-volume relationship [105]. 

Laser-induced fluorescence photofragment spectroscopy studies with state-selective interfragment recoil measurement have not been performed to any appreciable extent. A preliminary kind of experiment has recently been carried out in an MPD case by using the time-of-flight technique under bulk condition and with rather limited spectral resolution. A Doppler spectroscopy study has been carried out in a one-photon dissociation case where electronically excited fragments were produced under bulk condition, and linewidth measurement was made in emission interferomet-rically. A first experiment with tunable LIF detection has been made recently by McDonald et al., who dissociated HN3 at 266 nm and... 

Fig. 1. Doppler spectroscopy velocity vector diagram Vp parent molecule velocity, Vr fragment recoil velocity in CM-system, VL=Vp+Vn fragment velocity in lab-system, Vu Doppler component in probe laser direction.

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