Visible spectrum microscopy

Historically, this has been the most constrained parameter, particularly for confocal laser scanning microscopes that require spatially coherent sources and so have been typically limited to a few discrete excitation wavelengths, traditionally obtained from gas lasers. Convenient tunable continuous wave (c.w.) excitation for wide-held microscopy was widely available from filtered lamp sources but, for time domain FLIM, the only ultrafast light sources covering the visible spectrum were c.w. mode-locked dye lasers before the advent of ultrafast Ti Sapphire lasers. 

Inorganic nanotubes derived from WS2 may find application as tips in scanning probe microscopy. The feasibility of using such tips in inspecting microelectronic circuitry has now been demonstrated. The tips produced from WS2 nanotubes can outperform the microfabricated Si tip counterparts with respect to resilience and surface passivity [107]. Additional advantages of WS2 nanotubes include tunable electrical conductivities and strong light absorption in the visible spectrum. These properties may provide additional application opportunities in areas such as nanoelectronics and photocatalysis. 

In addition to electronic behavior, the optical properties of gel-phase materials have come under particular scrutiny. For example, it is possible to generate highly fluorescent nanostructured materials in which the electronic demands of substituents on the gelator framework tune the fluorescence wavelength of the soft material (Figure 14). Such systems can therefore be color tuned across the visible spectrum, with differently colored nanowires being visualized by using fluorescence microscopy techniques. 

The optical microscope is a sophisticated instrument capable of providing images with a resolution of the order of 1 p,m, molecular information via birefringence, and chemical information via colour changes or through the use of specific dyes. When these factors are combined with relative ease of sample preparation (c.f. electron microscopy) and purchase cost, optical microscopy is a powerful technique for the study of many materials, particularly those that transmit in the visible region of the spectrum. 

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