聚苯乙烯的激光闪光光解

FLASH PHOTOLYSIS OF POLYSTYRENE WITH LASER

用１．０６μｍ激光对聚苯乙烯的光解进行了研究；用质谱法对激光离解碎片进行了在线检测，得到了碎片粒子的平均质量、量子要求量以及质荷比为１０４的粒子百分含量与时间关系曲线；对高分子化合物的激光离解质谱分析进行了探讨。

AbstractThis paper describes the flash photolysis of polystyrene with a pulsed Nd-Glass laser(wavelength 1.06μm,10￣(-4)s duration, pulse energy 2.5J/shot),that run after Q-switchedmanner giving 2.5J per pulse at 1.06μm and about 10￣(-8) duration.In this experiment a modelFinnigan MAT 4510 chromatograph/mass spectrometer is used to detect products speedily intime.The focused laser beam(to a spot size of about 0.5mm in diameter)through the windowon the ion source of the instrument irradiates a sample of polystyrene on the centre of the ionvolume,so that the polystyrene dissociate, vapour, then the sample inection is achieved.Bythe fast analyser of the quart-pole mass spectrometry the sample was scan speedily.While thecomputer processes the received signal and stores the mass spectrum.The experimental parameter : The sample loss weight 19μg per laser shot. The average massnumber of all the product particles is 99. The quantum requirement β=N/n=1.16 × 10￣2. Fig.2a andFig. 3a show that the mass spectrometric data can be collected in tens seconds after a lasershot.In case of the Q-switched manner the spoctrum of the photolysis is simpler than that ofwithout Q-switched. Because the pulse duration and the energy effected on it.The differenceof the relative intensity between the lines and the difference of the product components indicatethat the laser photolysis of the macromolecular compounds have some regularity, while havesome randomness. We suggested that there are practical limitations on distinguishingmacromolecular compounds by a laser photolysis. Not only incident energy must be controled,but also need to precent the bias induced by randomness with a batch of mass spectrum.The randomness of a laser photolysis mass spectrum of the macromolecular compoundsshows the intramolecular energy transfer performance between high vibrational states of aground electron state.