Surface Observation Using Optical Microscopy

Surface Observation Using Optical Microscopy 2.1. Light Microscopy... 

The surface morphology of block copolymer films can be investigated by atomic force microscopy. The ordering perpendicular to the substrate can be probed by secondary ion mass spectroscopy or specular neutron or x-ray reflectivity. Suitably etched or sectioned samples can be examined by transmission electron microscopy. Islands or holes can have dimensions of micrometers, and consequently may be observed using optical microscopy. 

Powerful methods that have been developed more recently, and are currently used to observe surface micro topographs of crystal faces, include scanning tunnel microscopy (STM), atomic force microscopy (AFM), and phase shifting microscopy (PSM). Both STM and AFM use microscopes that (i) are able to detect and measure the differences in levels of nanometer order (ii) can increase two-dimensional magnification, and (iii) will increase the detection of the horizontal limit beyond that achievable with phase contrast or differential interference contrast microscopy. The presence of two-dimensional nuclei on terraced surfaces between steps, which were not observable under optical microscopes, has been successfully detected by these methods [8], [9]. In situ observation of the movement of steps of nanometer order in height is also made possible by these techniques. However, it is possible to observe step movement in situ, and to measure the surface driving force using optical microscopy. The latter measurement is not possible by STM and AFM. 

In the present chapter, we discuss the principles and techniques commonly used for observing biological surface structures, including optical microscopy (light microscopy, laser scanning confocal microscopy), electron microscopy (scanning electron microscopy, transmission electron microscopy), and scanning probe microscopy. We describe and contrast the sample preparation of each technique. Quantitative data analysis as well as the limitations of each technique is also addressed. 

Fig. 8. Concentration dependence of ultrasound backscatter signal by plates coated with a layer of targeted microbubbles. Surface concentrations of microbubbles (as observed by bright-field optical microscopy, bottom) increase from left to right. Imaging performed using a fundamental frequency scheme. Samples placed on top of an ultrasound tissue phantom. Reprinted from Advanced Drug Delivery Reviews v. 37, A.L. Klibanov, Targeted delivery of gas-filled microspheres, contrast agents for ultrasound imaging, p. 145. Copyright, 1999, with permission from Elsevier Science...

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