Polystyrene excimer, time profiles

Very recently Kouchi et al. constructed an ion beam pulse radiolysis system and use it for the study of the LET effect in irradiated polystyrene thin films [106]. The nanosecond pulsed MeV ion beam with the variable repetition rate was obtained by chopping ion beams from a Van de Graaff. Time profiles of the excimer fluorescence from polystyrene thin films, excited by He+ impact, were... 

The investigation of the ion beam interaction with polystyrene by means of ion beam pulse radiolysis has the advantage that the reactive intermediates can be directly detected. Time profiles of the excimer fluroescence from ion irradiated polystyrene were measured using the polystyrene thin films. Thus, the transient phenomenon excited by the ion with a definite kinetic energy was observed. 

In ion-beam irradiated polystyrene, some kinds of reactive intermediates are produced. The excimer, which is one of the reactive intermediates, emits intense fluorescence. Thus, we measured the time profiles of the excimer fluorescence (328.5 nm) from ion irradiated polystyrene thin films. One of the results is shown in Fig. 6a and b for irradiation with 0.6 MeV He+ (several hundred pA beam current). In Fig. 6a, the irradiation time dependence of the excimer fluorescence intensity is shown. In Fig. 6b, the time profile (I) was recorded with an irradiation time of 0 s-139 s (low dose-time profile), and (II) in the irradiation time of 1839 s- 3839 s (high dose-time profile). The following experimental results were obtained. 

Fig. 7. Time profiles of the excimer from polystyrene resist films (0.5 pm thick) irradiated with ions. These time profiles were not influenced by the quenching seen in Fig. 6. The straight lines correspond to the fluorescence lifetime obtained by the electron pulse radiolysis study of polystyrene [38], From Ref. 35...

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