Gharibshahi Elham, Saion Elias, Johnston Roy Luigi, Ashraf Ahmadreza
Department of Physics, Faculty of Science, University of Putra Malaysia (UPM), 43400, UPM Serdang, Selangor, Malaysia; Department of Electrical and Computer Engineering, University of Texas at San Antonio (UTSA), One UTSA Circle, San Antonio, Texas, 78249, USA.
Department of Physics, Faculty of Science, University of Putra Malaysia (UPM), 43400, UPM Serdang, Selangor, Malaysia.
Appl Radiat Isot. 2019 May;147:204-210. doi: 10.1016/j.apradiso.2019.02.015. Epub 2019 Feb 22.
Platinum nanoparticles were synthesized using the gamma radiolytic technique in an aqueous solution containing Platinum tetraammine chloride in presence of poly vinyl pyrrolidone, isopropanol, tetrahydrofuran and deionized water. The gamma irradiation was carried out in aCo gamma source chamber and the particle size was found to decrease from 4.88 to 3.14 nm on increasing the gamma radiation dose from 80 to 120 kGy. UV-visible absorption spectra were measured and revealed two steady absorption maxima at 216 and 264 nm in the UV region, which was blue shifted (i.e. toward lower wavelength) with decreasing particle size. By taking the conduction electrons of an isolated particle that are not entirely free, but instead bound to their respective quantum levels, the optical absorption of platinum nanoparticles can be calculated via intra-band quantum excitation for particle sizes similar to those measured experimentally. We found that the calculated absorption maxima of electronic excitations matched the measured absorption maxima well. This finding suggests that the optical absorption of metal nanoparticles commonly applied in nanoscience and nanotechnology can be described accurately by the quantum excitation of conduction electrons.
在含有四氨合铂（II）氯化物的水溶液中，于聚乙烯吡咯烷酮、异丙醇、四氢呋喃和去离子水存在的条件下，采用伽马辐射分解技术合成了铂纳米颗粒。伽马辐射在钴伽马源腔室中进行，发现随着伽马辐射剂量从80千戈瑞增加到120千戈瑞，颗粒尺寸从4.88纳米减小到3.14纳米。测量了紫外可见吸收光谱，结果显示在紫外区域216纳米和264纳米处有两个稳定的吸收最大值，随着颗粒尺寸减小，这些吸收峰发生蓝移（即向更低波长方向移动）。对于与实验测量尺寸相似的颗粒，通过考虑孤立颗粒中并非完全自由而是束缚在各自量子能级上的传导电子，可通过带内量子激发来计算铂纳米颗粒的光吸收。我们发现计算得到的电子激发吸收最大值与测量得到的吸收最大值吻合良好。这一发现表明，纳米科学和纳米技术中常用的金属纳米颗粒的光吸收可以通过传导电子的量子激发来准确描述。
