Surface, electrical and mechanical modifications of PMMA after implantation with laser produced iron plasma ions

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• 作者：Qazi Salman Ahmed ; Shazia Bashir ; ^{shaziabashir@gcu.edu.pk" class="auth_mail" title="E-mail the corresponding author} ; Sohail Abdul Jalil ; Muhammad Kaif Shabbir ; Khaliq Mahmood ; Mahreen Akram ; Ayesha Khalid ; Nazish Yaseen ; Atiqa Arshad
• 关键词：PMMA ; Fe ions ; Laser Produced Plasma ; Chain scission ; Crosslinking
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2016
• 出版时间：1 July 2016
• 年：2016
• 卷：378
• 期：Complete
• 页码：1-7
• 全文大小：1492 K

文摘

Laser Produced Plasma (LPP) was employed as an ion source for the modifications in surface, electrical and mechanical properties of poly methyl (methacrylate) PMMA. For this purpose Nd:YAG laser (532 nm, 6 ns, 10 Hz) at a fluence of 12.7 J/cm² was employed to generate Fe plasma. The fluence and energy measurements of laser produced Fe plasma ions were carried out by employing Thomson Parabola Technique in the presence of magnetic field strength of 0.5 T, using CR-39 as Solid State Nuclear Track Detector (SSNTD). It has been observed that ion fluence ejecting from ablated plasma was maximum at an angle of 5° with respect to the normal to the Fe target surface. PMMA substrates were irradiated with Fe ions of constant energy of 0.85 MeV at various ion fluences ranging from 3.8 × 10⁶ ions/cm² to 1.8 × 10⁸ ions/cm² controlled by varying laser pulses from 3000 to 7000. Optical microscope and Scanning Electron Microscope (SEM) were utilized for the analysis of surface features of irradiated PMMA. Results depicted the formation of chain scission, crosslinking, dendrites and star like structures. To explore the electrical behavior, four probe method was employed. The electrical conductivity of ion irradiated PMMA was increased with increasing ion fluence. The surface hardness was measured by shore D hardness tester and results showed the monotonous increment in surface hardness with increasing ion fluence. The increasing trend of surface hardness and electrical conductivity with increasing Fe ion fluence has been well correlated with the surface morphology of ion implanted PMMA. The temperature rise of PMMA surface due to Fe ion irradiation is evaluated analytically and comes out to be in the range of 1.72 × 10⁴ to 1.82 × 10⁴ K. The values of total Linear Energy Transfer (LET) or stopping power of 0.8 MeV Fe ions in PMMA is 61.8 eV/Å and their range is 1.34 μm evaluated by SRIM simulation.