Measurement method of diffusion coefficient in polymer thin film by single fluorescent molecule detection method

摘要

Disclosed is a method for measuring the diffusion coefficient of a low-molecular substance contained in a cured material using a single fluorescent molecule detecting technique. In this method, a diffusion stage of a low-molecular substance contained in a cured material is identified by a single fluorescent molecule detecting technique comprising a combination of an optical microscope with a CCD camera. The diffusion coefficient of a fluorescent molecule excited by a laser beam in the rotation or translational movement of the fluorescent molecule in the cured material is determined based on a change in position of bright points with the elapse of time by the fluorescent molecule contained in the cured material and a diffusion equation. More specifically, the fluorescent molecule is excited by a process comprising providing an Ar ion laser, a He-Ne laser, or a semiconductor laser of a type in which continuous wave oscillation is performed in an ultraviolet to visible region and transmitting the laser beam through a high-precision laser line filter having a transmission bandwidth of not more than 4 nm and a wavelength differentiating filter to separate excitation light and fluorescence. The method utilizes a CCD camera comprising a Peltier element cooling backside illumination-type CCD detector that cools a CCD element to a temperature of -70°C to -200°C to remove thermal noise with high accuracy.