Development of Laser-Induced Material Transfer in Nanometer Regions

利用激光烧蚀和激光注入的方法，功能有机分子已经在聚合物薄膜上被操纵成小到450 nm的荧光特征。这项技术利用压电驱动器来定位吸管，吸管的孔径为100 nm，在聚合物薄膜上方数十纳米处的尖端掺入有机分子。随后使用全宽度为3 ns的半最大激光脉冲来照射移液管，该激光脉冲由光纤引导到尖端。这种烧蚀限制方法为在指定区域放置功能有机分子提供了精细的空间控制，并将在光电子学中得到应用。它还可以应用于药物输送或生物技术，因为原则上不同功能的不同分子可以以相同的方式被操纵以用于不同的目的。利用扫描隧道显微镜STM对有机溶剂中的掺锡氧化铟ITO进行了纳米尺度的表面修饰。这种表面修饰是由于在隧道隙之间施加10V的局域场蒸发所致。在表面修饰过程中和表面修饰后，观察到在STM针尖纳米火花下有白光闪烁。在纯溶剂中添加离子物种，即使在较低的电压下也会产生纳米火花，但在这种情况下，表面修饰并未发生。认为部分ITO以离子的形式溶解在溶液中，在这些诱导离子的存在下导致电子雪崩，从而获得了控制激光诱导分子、电子和离子在空气/固体或液体/固体表面转移的基础知识。

Functional organic molecules have been manipulated into fluorescent features as small as 450 nm on a polymer film using a method derived from laser ablation and laser implantation. The technique utilizes a piezodriver to position a pipette, having a 100 nm aperture and doped at the tip with organic molecules, tens of nanometers above a polymer film. The pipette is subsequently irradiated using 3 ns full width at half maximum laser pulses guided down to the tip by a fiber optic. This method of ablation confinement gives fine spatial control for placing functional organic molecules in a designated region and will have applications in optoelectronics. It could also be applied to drug delivery or biotechnology, because in principle, different molecules of diverse function can be manipulated in the same way for various purposes.A nanometer-scale surface modification of tin-doped indium oxide ITO in organic solvent was performed using a scanning tunneling microscope STM. The surface modification was attributed to localized field evaporation upon applying 10 V between the tunneling gap. White light sparking beneath the STM tip nanospark was observed during and after the surface modification. The addition of ionic species into the otherwise pure solvent also induced a nanospark even when applying lower voltages, but in this case, surface modification did not occur. It is considered that a part of the ITO becomes dissolved in solution as ions, which results in electron avalanche in the presence of these induced ions.Thus, fundamental knowledge was obtained for controlling laser-induced transfer of molecules, electrons, and ionic species at air/solid or liquid/solid surfaces.