**7. References**

Andreas, J. M.; Tucker, W. B. (1938). Boundary Tension by Pendant Drop.*J. Phys. Chem*.,42, pp. 1001-1019.

Armellini, F.J., Tester, J.W. (1994). Precipitation of sodium chloride and sodium sulfate in water from sub- to supercritical conditions:150 to 550ºC, 100 to 300 bar. *J. Supercrit. Fluids*, 7, pp.147–158.

distribution of droplets is produced in this regime, it is very well correlated with the

When the flow rate is increased to 3 mL/min, it is estimated that the transition is complete, and the liquid is atomized. The large quantity of fine precipitate with foamy texture obtained both on the walls and accumulated in the filter (characteristic of nanoparticles) would have originated from the fully atomized and homogeneous dispersion that is occurring in the precipitation chamber. With 5 mL/min it was obtained similar results in

The hydrodynamics of the SAS process has been revised. Nozzle device, liquid flow rate and pressure effects on hydrodynamics have been taken into account. Flow regimes observable in the SAS related literature have been described. Dripping mode is simply due to the use of liquid flow rates that are too low to produce a continuous liquid flow and do not produce atomization. Rayleigh breakup, sinusoidal wave break up, and atomization regimes and, particularly their competition at some process conditions require a detailed analysis. The ability to identify and characterize these regimes drives future system improvements, including lighting enhancements laser-induced fluorescence, and higher

Morphology of the precipitated particles can be related to flow or mixing regimes. In the ampicillin case, two differentiated types of morphology can be identified in the precipitated experiments: spherical nanoparticles of ampicillin that are obtained from a fine precipitate with foamy texture, and particles of ampicillin with irregular forms and larger size, which are characteristic of the precipitate formed by aggregates, compact films, and rods. It has been correlated the morphologies of the particles obtained in the ampicillin precipitation assays and the estimated regimes as a function of the physicochemical properties and of the

However, the results from the application of these correlations cannot explain the morphologies of the precipitates obtained in some experiments. This fact can be due to

Due to the great complexity of the SAS process, factors such as the ternary phase equilibrium, matter transfer between the phases, and the kinetics of nucleation and growth

We are grateful to the Spanish Ministry of Education and Science (Project No. CTQ2010-

Andreas, J. M.; Tucker, W. B. (1938). Boundary Tension by Pendant Drop.*J. Phys. Chem*.,42,

Armellini, F.J., Tester, J.W. (1994). Precipitation of sodium chloride and sodium sulfate in

water from sub- to supercritical conditions:150 to 550ºC, 100 to 300 bar. *J. Supercrit.* 

experimental obtained results (Tenorio et al., 2009).

**5. Conclusions** 

spatial resolution cameras.

**6. Acknowledgment** 

**7. References** 

19368) for financial support.

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**9** 

*India* 

Sanjeev R. Inamdar

*Department of Physics,* 

*Laser Spectroscopy Programme,* 

*Karnatak University, Dharwad* 

**Rotational Dynamics of Nonpolar and Dipolar** 

**Molecules in Polar and Binary Solvent Mixtures** 

The absorption of photons by a molecule leads to its excitation. An electronically excited molecule can lose its energy by emission of ultraviolet, visible, infrared radiation or by collision with the surrounding matter. Luminescence is thus the emission of photons from excited electronic energy levels of molecules. The energy difference between the initial and the final electronic states is emitted as fluorescence or phosphorescence (Lakowicz, 2006). Fluorescence is a spin-allowed radiative transition between two states of the same multiplicity (e.g., S1 → S0) whereas; phosphorescence is a spin-forbidden radiative transition

The mechanisms by which electronically excited molecules relax to ground state are given by the Jablonski diagram as shown in Fig. 1. The absorption of a photon takes a molecule from ground state (singlet state, S0) to either first excited state (singlet state, S1) or second

Fig. 1. Jablonski diagram of transitions among various electronic energy levels

→S0).

**1. Introduction** 

between two states of different multiplicity (e.g., T1

