Fig. 18 FTIR-PAS spectra of single nylon 6,6 fibers with different cross-sectional geometries and fiber diameters.

2. Single coal particles

Microparticles are supported on very fine tungsten needles for FTIR-PAS analysis. Manipulation of microparticles by tungsten needles is a common practice in optical microscopy and is often done by hand under a microscope by experienced microscopists. Particles usually attach to the needle tip by electrostatic attraction. In some instances when humidity is high, particles are best attached using a speck of electrically conducting colloidal graphite glue that can be obtained from distributors of microscopy supplies. The glue is made to flow using isopropanol, then the particle is rapidly touched before the glue dries. This latter method of attachment allows for both FTIR and SEM analysis of microsamples after mounting.
Microparticles are manipulated and mounted for FTIR-PAS analysis using items shown in the right foreground and background of Fig. 14. The sample holder in the photograph contains a desiccant holder, tungsten needle socket, and polished conical insert that are used in FTIR-PAS particle analysis. In the right foreground and background are a tungsten needle storage holder and a micromanipulator for the needles, respectively. The micromanipulator attaches to a laboratory microscope as shown in Fig. 19 and allows precise control of the needle point.