Photophoretic spectrum

Since the photophoretic force depends on the electromagnetic absorption efficiency Q y , which is sensitive to wavelength, photophoretic force measurements can be used as a tool to study absorption spectroscopy. This was first recognized by Pope et al. (1979), who showed that the spectrum of the photophoretic force on a 10 foa diameter perylene crystallite agrees with the optical spectrum. This was accomplished by suspending a perylene particle in a Millikan chamber with electro-optic feedback control and measuring the photophoretic force as a function of the wavelength of the laser illumination. Improvements on the technique and additional data were obtained by Arnold and Amani (1980), and Arnold et al. (1980) provided further details of their photophoretic spectrometer. A photophoretic spectrum of a crystallite of cadmium sulfide reported by Arnold and Amani is presented in Fig. 11. 

Fig. 11. A photophoretic spectrum of a CdS crystallite obtained by Arnold and Amani (1980) with a modified Millikan condenser. Reprinted with permission from Arnold, S., and Amani, Y., Optics Letters 5, 242-244, Copyright 1980, The Optical Society of America.

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See also in sourсe #XX -- [ , ]

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