Positron annihilation lifetime of irradiated polyimide Japan Atomic

Positron annihilation lifetime of irradiated polyimide Japan Atomic Energy Agency １ Graduate School of Ibaraki University ２ HIRADE, Tetsuya１、２; OKA, Toshitaka１; MORISHITA, Norio１; IDESAKI, Akira１; SHIMADA, Akihiko１ Trial of observation of free volume change of polyimide polymers with no Ps formation.

from Dupont web page

counts lifetime spectrum of kapton no Ps formation channel

No Ps Formation Spur Reaction Model (by Mogensen) M 　→ M+ + e- Ionization -R + e- → -R- electron scavenging -S + e+ →　[-S, e+] positron scavenging

############ F I N A L R E S U L T S ############ CONVERGENCE OBTAINED AFTER 10 ITERATIONS VARIANCE OF THE FIT = 1. 085 WITH STANDARD DEVIATION 0. 051 CHI-SQUARE = 818. 97 WITH 755 DEGREES OF FREEDOM SIGNIFICANCE OF IMPERFECT MODEL = 94. 73 % ------------------------------------RESOLUTION FUNCTION: G W S 1 0 1 FWHM (NS) : 0. 1635 STD DEVIATIONS : 0. 0005 INTENSITIES (%) : 100. 0000 SHIFTS (NS) : 0. 0000 STD DEVIATIONS : FIXED ------------------------------------LIFETIME COMPONENTS: L T I 1 0 0 LIFETIMES (NS) : 0. 3842 STD DEVIATIONS : 0. 0004 INTENSITIES (%) : 100. 0000 STD DEVIATIONS : 0. 0000 ------------------------------------BACKGROUND: B 1 COUNTS/CHANNEL : 1. 0340 STD DEVIATION : MEAN ------------------------------------

　　　　　　　 λfree positron = λM　　+　　λF λM: with the electrons on the chain positron trapped λF: with the electrons on the surrounding chains

Fig. 1 Temperature dependence of positron annihilation lifetime in Kapton.

Positron annihilation lifetime of irradiated polyimide Japan Atomic Energy Agency １ Graduate School of Ibaraki University ２ HIRADE, Tetsuya１、２; OKA, Toshitaka１; MORISHITA, Norio１; IDESAKI, Akira１; SHIMADA, Akihiko１ Trial of observation of free volume change of polyimide polymers with no Ps formation.

counts lifetime spectra of electronirradiated kapton (8 k. Gy/s) channel

Elongation (%)

Observation of positron localization Delayed Ps formation with trapped electrons positron localization time : 70 -80 ps Polyethylene at 20 k open circle: in darkness filled circle: under light N. Suzuki, T. Hirade, F. Saito, T. Hyodo, Radiation Physics and Chemistry, 68 (2003) 647 -649 T. Hirade, N. Suzuki, F. Saito, T. Hyodo, phys. stat. sol. (c) 4, No. 10 (2007) 3714 -3717

t 2 CCl 4 concentration (M) The intensity of ortho-Ps component in the lifetime spectra versus CCl 4 concentration in n-hexane. T. Hirade and O. E. Mogensen / Chemical Physics 170 (1993) 249256

Conclusion • Free positron annihilation lifetime might be able to give information of change of free volume of polymers, such as Kapton. But "free positron" is not free!! We should understand positron chemistry !! • Kapton lifetime for source correction for the lifetime analysis should not be obtained with no irradiated Kapton and might be about 378 ps at room temperature.

Ďakujem !!

γirradiation EB