A time-resolved ultramicroscope was developed to monitor the process of pulse-laser-induced melting of 9,10-dicyanoanthracene microcrystals on poly(ethyl methacrylate) films. The microscope can detect sub-micrometer particles, but with an image (spacial) resolution of 2μm and a time resolution of 400ps. Quantitative comparison between images obtained at a certain time delay after an excitation laser pulse and a pre-irradiated image is achieved using a correlation function. It was found that crystals having a size of about 10μm turn in hot liquid droplets within the nanosecond excitation pulse after which 80% of the droplets solidify with a time constant of 9ns. The residual 20% of hot liquid droplets appear to have either evaporated or fused and dispersed into the polymer with a time constant of 15ns.
|Number of pages||6|
|Journal||Journal of Photochemistry and Photobiology A: Chemistry|
|State||Published - 3 Dec 2001|
- Laser-induced melting
- Nanosecond photo-fusion
- Time-resolved ultramicroscope