A new method for estimating the extinction efficiency of polystyrene microsphere by micro-FTIR spectroscopy.

ABSTRACT

The IR spectra of a single, isolated polystyrene sphere with diameter of 4.46µm under different aperture sizes have been measured by Micro-FTIR spectrometer and the scattering signal can be seen obviously. Based on Mie scattering theory, a feasible method has been proposed to estimate the extinction efficiency (Qext) of microsphere. Qext from Mid-IR spectroscopy is consistent well with that derived from MiePlot software. It shows that the extinction efficiency of microsphere with the size of the Mid-IR range (2.5µm-25µm), which exhibits weak IR absorption, can be obtained by using the present method based on recorded Micro-FTIR spectra.