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Methods to probe the molecular structure of living cells are of paramount importance in understanding drug interactions and environmental influences in these complex dynamical systems. The coupling of an acoustic levitation device with a micro-Raman spectrometer provides a direct molecular probe of cellular chemistry in a containerless environment minimizing signal attenuation and eliminating the affects of adhesion to walls and interfaces. We show that the Raman acoustic levitation spectroscopic (RALS) approach can be used to monitor the heme dynamics of a levitated 5 microL suspension of red blood cells and to detect hemozoin in malaria infected cells. The spectra obtained have an excellent signal-to-noise ratio and demonstrate for the first time the utility of the technique as a diagnostic and monitoring tool for minute sample volumes of living animal cells.

The surface temperature of evaporating acoustically levitated drops has been monitored by IR-thermography. The thermography system has been calibrated by simultaneous measurements with a thin thermocouple. The integral IRemission coefficients of a few pure liquids have been derived. Evaporation processes of pure liquids and of binary mixtures of liquids have been studied with levitated drops. Using drop surface temperatures, we were able to calculated analytically binary gas-diffusion coefficients of liquids in ambient air.KEY WORDS: acoustic levitation; binary gas-diffusion coefficients; integral emissivity; IR-thermography; pure and binary mixtures of liquids; surface temperature.

Evaporation constants of acoustically levitated drops from the homologue series of n-alkanes and 1-alkanols in ambient air have been evaluated by size and temperature measurements. The size of the pure liquid drops, within a diameter range of 0.1 to 2.5 mm, was monitored using a CCD camera, while temperature measurements were carried out by IR thermography. During drop evaporation, water from a humid environment with a relative humidity between 5 and 80% was condensed on the drop surface and in the case of n-pentane, the condensed water froze as a result of the evaporative cooling.