Time-resolved infrared spectroscopy millisecond

The rate of polymerization and the cure penetration can be further increased by employing powerful lasers as radiation source, the exposure time dropping then into the millisecond range. Polymer relief images were thus obtained at micronic resolution by simply scanning the photosensitive plate with a highly focused laser beam. The kinetic profiles of such ultrafast reactions were directly record by using time-resolved infrared spectroscopy which allows instantaneous evaluation at any moment of the actual rate of polymerization and the precise amount of residual unsaturation in the cured polymCT. 

The detection of short-lived transient species is often achieved by flash photolysis where an extremely short flash of UV/Vis radiation from a laser generates a high concentration of transient species, and a second probe beam monitors any changes that occur after the flash. Traditionally, UVA is spectroscopy has been used as a detection method. However, time-resolved infrared spectroscopy (TRIR), a combination of UV flash photolysis and fast IR detection, also has a long history. There are several different approaches to fast IR spectroscopy and the method of choice depends upon the timescale of the reaction. Measurements on the nanosecond to millisecond timescale are obtained using point-by-point techniques or by step-scan FTIR. In the point-by-point approach, a continuous wave IR laser (GO or diode) or globar is used as the IR source, which is tuned to one particular IR frequency (Figure 3). ... 

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